A post-grouting type precast pile

Abstract

The utility model relates to the technical field of foundation and foundation, disclose a kind of post-grouting precast pile, post-grouting precast pile includes: pile body and post-grouting device;Pile body includes one section or multiple sections pile body, first grouting pipe is arranged in pile body;Post-grouting device is set between pile body bottom end and adjacent two sections of pile body, and it includes support frame, grout storage bag and closed grouting component, support frame includes: top, bottom plate and support, support both ends are connected with the connector on top and bottom plate, grout storage bag is located outside support, grout storage bag, support and top, bottom plate and the connector thereon are enclosed to form grout storage cavity, closed grouting component is set to top plate, and each closed grouting component is communicated with a first grouting pipe.The utility model grout storage bag grouting, support frame can resist vertical direction grouting pressure, and grout storage bag can only expand horizontally.Grating pressure is not limited by pile body pullout resistance, and grout storage bag expands, and contact area with stratum increases, and precast pile bearing capacity and pullout resistance are greatly improved.

Description

Technical Field

[0001] This utility model relates to the field of foundation technology, specifically to a post-grouting precast pile. Background Technology

[0002] Pile foundations can safely transfer the load of the superstructure to stable soil or rock layers deep underground, while solving problems such as insufficient bearing capacity and excessive settlement, providing a stable foundation support for the building. Pile foundation construction is also a core technical means to treat weak foundations and improve bearing capacity during foundation construction.

[0003] Precast piles are a commonly used type of pile foundation. They are first prefabricated in a factory and then transported to the construction site for driving using hammering or static pressure. In existing technology, to improve the pull-out resistance of precast piles, grouting pipes are pre-embedded in the pile body, and a grout storage bag is placed at the bottom of the pile. Grout is injected into the storage bag through the grouting pipes in a closed loop. As grouting continues, the storage bag expands outwards, and after the grout solidifies, it eventually forms an enlarged head at the bottom of the pile. This increases the contact area between the precast pile and the ground, thereby improving the bearing capacity and pull-out resistance of the precast pile.

[0004] However, if the grouting pressure is too low during the grouting process, i.e., less than the soil strength, the grout storage bag will not be able to expand outward; but if the grouting pressure is too high, i.e., greater than the pull-out resistance of the pile, the pile will lift up. Therefore, the expansion volume of the grout storage bag is often limited by the grouting pressure, and the contact area with the soil does not reach the expected effect, which will affect the final bearing capacity and pull-out resistance of the precast pile. Utility Model Content

[0005] This utility model provides a post-grouting precast pile to solve the problem that the expansion volume of the grout storage bag at the bottom of the precast pile is limited by the grouting pressure and the contact area with the stratum cannot reach the expected effect, which will affect the final bearing capacity and pull-out resistance of the precast pile.

[0006] In a first aspect, this utility model provides a post-grouting precast pile, comprising: The pile body includes one or more sections of pile body arranged in a vertical direction, and a plurality of first grouting pipes are provided in the pile body; A post-grouting device is provided at the bottom end of the pile body and between two adjacent pile sections. The post-grouting device includes a support frame, a grout storage bag, and closed-loop grouting components. The support frame includes a top plate, a bottom plate, and a support member. Both ends of the support member are connected to the top plate and the bottom plate, respectively. The bottom plate of the post-grouting device at the bottom end of the pile body is also provided with an end plate. The bottom surface of the top plate is provided with a first connector, and the top surface of the bottom plate is provided with a second connector. Both ends of the grout storage bag are connected to the first connector and the second connector, respectively, and the grout storage bag is located outside the support member. The grout storage bag, the top plate, the first connector, the bottom plate, the second connector, and the support member together form a grout storage cavity. Multiple closed-loop grouting components are provided on the top plate. The inlet end of each closed-loop grouting component is connected to a first grouting pipe of the upper pile section, and its outlet end is located in the grout storage cavity.

[0007] Beneficial effects: During closed-loop grouting of the grout storage bag, the top and bottom plates of the supporting frame can resist the vertical grouting pressure and limit the vertical expansion of the grout storage bag, allowing it to expand only in the horizontal direction. Therefore, the grouting pressure is no longer limited by the pile's pull-out resistance, and even with higher grouting pressure, the pile will not lift. After the grout storage bag expands, the contact area between the precast pile and the stratum is larger, achieving the desired effect. Ultimately, the bearing capacity and pull-out resistance of the precast pile are significantly improved.

[0008] In an optional embodiment, a second grouting pipe is provided in the pile body, and the post-grouting device further includes: an open grouting component, the two ends of which are respectively connected to the top plate and the bottom plate, and its top end is connected to the second grouting pipe of the upper section of the pile body, and its bottom end is connected to the grouting space of the second grouting pipe of the lower section of the pile body or the end plate.

[0009] Beneficial effects: Grouting can be injected into the soil at the bottom of the pile through the second grouting pipe and open grouting components, allowing the grout to seep into the soil. After the grout solidifies, it can improve the pull-out resistance and bearing capacity of the precast pile.

[0010] In an optional embodiment, the support includes a telescopic sleeve and support columns. The two ends of the telescopic sleeve are connected to the top plate and the bottom plate, respectively. A plurality of support columns are spaced apart along the circumference of the telescopic sleeve. The telescopic sleeve can extend and retract along the height direction of the support frame under the drive of an external force.

[0011] Beneficial effects: By setting a telescopic sleeve, the overall height of the post-grouting device can be changed. After the precast pile is driven, the bottom plate of the post-grouting device is hammered with a tool to extend the telescopic sleeve, which can then drive the pile tip to press against the soil below. At the same time, the effective expansion volume of the grout storage bag after grouting can be larger, thereby improving the support stability of the precast pile.

[0012] In an optional embodiment, the post-grouting device further includes a tension cable, the two ends of which are respectively connected to the top plate and the bottom plate.

[0013] Beneficial effects: The tension cable connects the top and bottom plates of the rear grouting device to prevent excessive external force from causing the telescopic sleeve to break during the extension process of the telescopic sleeve when the bottom plate of the rear grouting device is struck with a tool.

[0014] In an optional embodiment, the open grouting component includes: a grouting hose and a connector, two connectors being respectively disposed on the top plate and the bottom plate, the two ends of the grouting hose being respectively connected to the two connectors, and the connector on the bottom plate of the post-grouting device disposed at the bottom end of the pile body is connected to a grouting one-way valve.

[0015] Beneficial effects: As the telescopic sleeve extends, the distance between the top and bottom plates also increases. The grouting hose can adapt to the changes in the telescopic sleeve, preventing the pipe from breaking and ensuring the smooth progress of subsequent grouting work.

[0016] In an optional embodiment, the closed grouting component includes: a grouting pipe section, a protective pipe section, and a sealing component. The top end of the grouting pipe section is connected to the top plate, and the bottom end of the grouting pipe section is provided with the protective pipe section. The upper part of the grouting pipe section is provided with a grout outlet hole, and the lower part of the grouting pipe section is provided with the sealing component.

[0017] In an optional embodiment, the diameter of the protective pipe section is smaller than the diameter of the grouting pipe section, and the protective pipe section is located on the side close to the grout storage bag.

[0018] In an optional embodiment, a rubber sleeve is fitted over the outside of the slurry outlet.

[0019] Beneficial effects: In a normal closed-loop grouting process, the bottom of the grouting pipe is sealed, and the grout enters the storage bag from the outlet. If a blockage occurs during grouting, preventing smooth grout injection, tools can be used to break the seal, allowing the grout to enter the storage bag from the bottom of the grouting pipe, thus clearing the blockage. Protective pipe sections prevent tools from touching and puncturing the storage bag during the clearing process.

[0020] In an optional embodiment, the first connector and the second connector are alternately formed with grooves and protrusions along the height direction of the support frame.

[0021] In an optional embodiment, the end plate comprises two plates arranged perpendicularly to each other. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the closed-loop grouting device before grouting when the pile body of the post-grouting precast pile of this utility model is a square pile. Figure 2 This is a schematic diagram of the closed-loop grouting device after the post-grouting process when the pile body of the post-grouting precast pile of this utility model is a square pile. Figure 3 This is a schematic diagram of the post-grouting device at the bottom of the pile body before closed-loop grouting when the pile body of the post-grouting precast pile of this utility model is a square pile. Figure 4 This is a schematic diagram of the closed-loop grouting device at the bottom of the pile body when the pile body of the post-grouting precast pile of this utility model is a square pile. Figure 5 for Figure 4 An enlarged schematic diagram of part A in the middle; Figure 6 for Figure 4 Enlarged schematic diagram of part B; Figure 7 This is a schematic diagram of the closed-loop grouting device before grouting when the pile body of the post-grouting precast pile of this utility model adopts pipe piles; Figure 8 This is a schematic diagram of the closed-loop grouting device after the post-grouting process when the pile body of the post-grouting precast pile of this utility model is made of pipe pile. Figure 9 This is a schematic diagram of the retracted state of the telescopic sleeve in the post-grouting device at the bottom of the pile body when the pile body of the post-grouting precast pile of this utility model adopts pipe pile. Figure 10 This is a schematic diagram of the extended state of the telescopic sleeve in the post-grouting device at the bottom of the pile body when the pile body of the post-grouting precast pile of this utility model adopts pipe pile. Figure 11 This is a schematic diagram of the grouting hose in the extended state of the telescopic sleeve of the post-grouting device at the bottom of the pile body when the pile body of the post-grouting precast pile of this utility model adopts pipe pile. Figure 12 This is a schematic diagram of the closed grouting process after the extension of the telescopic sleeve in the post-grouting device at the bottom of the pile body when the pile body of the post-grouting precast pile of this utility model is made of pipe pile. Figure 13 This is a schematic diagram of the pile driving steps when the pile body of the post-grouting precast pile of this utility model is a square pile; Figure 14 This is a schematic diagram of the open grouting process at the bottom of the pile when the pile body of the post-grouting precast pile of this utility model is a square pile; Figure 15 This is a schematic diagram of the closed grouting process when the post-grouting precast pile body of this utility model adopts a square pile. Figure 16 This is a schematic diagram of the pile driving steps when the pile body of the post-grouting precast pile of this utility model is made of pipe pile; Figure 17 This is a schematic diagram of the extension steps of the telescopic sleeve when the pile body of the post-grouting precast pile of this utility model is made of pipe pile; Figure 18 This is a schematic diagram of the steps involved in grouting and sealing the connection of the expansion sleeve when the pile body of the post-grouting precast pile of this utility model is made of pipe pile; Figure 19 This is a schematic diagram of the open grouting process at the bottom of the pile when the pile body of the post-grouting precast pile of this utility model is made of pipe pile; Figure 20 This is a schematic diagram of the closed grouting process when the post-grouting precast pile body of this utility model uses pipe piles.

[0024] Explanation of reference numerals in the attached figures: 1. Pile body; 11. Pile shaft; 2. First grouting pipe; 3. Post-grouting device; 31. Support frame; 311. Top plate; 312. Bottom plate; 313. Support component; 3131. Telescopic sleeve; 3132. Support column; 314. End plate; 315. First connector; 3151. Groove; 3152. Protrusion; 316. Second connector; 32. Grout storage bag; 33. Closed grouting component; 331. Grouting pipe section; 332. Protective pipe section; 333. Sealing component; 334. Grout outlet hole; 34. Open grouting component; 341. Grouting hose; 342. Connector; 343. Grouting check valve; 35. Tension cable; 4. Second grouting pipe. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0026] The following is combined with Figures 1 to 20 The following describes embodiments of the present invention.

[0027] According to an embodiment of the present invention, a post-grouting precast pile is provided, comprising: a pile body 1 and a post-grouting device 3. The pile body 1 includes one or more sections of pile shaft 11 arranged vertically, and a plurality of first grouting pipes 2 are provided in the pile shaft 11. The post-grouting device 3 is disposed at the bottom end of the pile body 1 and between two adjacent sections of the pile shaft 11. The post-grouting device 3 includes: a support frame 31, a grout storage bag 32, and a closed grouting component 33. The support frame 31 includes: a top plate 311, a bottom plate 312, and a support member 313. The two ends of the support member 313 are respectively connected to the top plate 311 and the bottom plate 312. The bottom surface of the bottom plate 312 of the post-grouting device 3 disposed at the bottom end of the pile body 1 is also provided with an end plate 314, the bottom surface of the top plate 311 is provided with a first connecting member 315, and the top surface of the bottom plate 312 is provided with an end plate 314. A second connector 316 is provided. The two ends of the slurry storage bag 32 are connected to the first connector 315 and the second connector 316 respectively. The slurry storage bag 32 is located outside the support 313. The slurry storage bag 32, the top plate 311, the first connector 315, the bottom plate 312, the second connector 316 and the support 313 together form a slurry storage cavity. Multiple closed grouting components 33 are provided on the top plate 311. The inlet end of each closed grouting component 33 is connected to a first grouting pipe 2 of the pile body 11 above, and its outlet end is located in the slurry storage cavity.

[0028] The pile body 11 is a precast reinforced concrete structure, generally a square pile or a pipe pile. Due to different manufacturing processes, square piles are usually solid, while pipe piles are usually hollow. To facilitate grouting, a first grouting pipe 2 is pre-embedded during the fabrication of the pile body 11. After the pile body 11 is fabricated, the first grouting pipe 2 is fixed in the pile body 11. The entire pile body 1 consists of one or more pile body sections 11, generally up to three sections, depending on the construction requirements. A connecting plate (such as an iron plate or steel plate) is also provided at the bottom of the pile body 11 to facilitate connection and fixation with the subsequent grouting device 3.

[0029] When only one pile body 11 is installed, the post-grouting device 3 is installed at the bottom end of the pile body 11 and connected to the connecting plate thereon. When multiple pile bodies 11 are installed, in addition to the post-grouting device 3 installed on the bottom surface of the bottom pile body 11, a post-grouting device 3 can also be installed between any two adjacent pile body 11 sections. The two ends of the post-grouting device 3 are connected to the bottom and top surfaces of the two adjacent pile body 11 sections, respectively. The connection method can be welding, bolting, bonding, or other methods. That is, regardless of how many pile body 11 sections the pile body 1 includes, a post-grouting device 3 will be installed at the bottom end of the pile body 1, while whether a post-grouting device 3 is installed between two adjacent pile body 11 sections depends on the geological conditions and construction requirements.

[0030] Furthermore, the post-grouting device 3 includes: a support frame 31, a grout storage bag 32, and a closed grouting component 33. The support frame 31 is a high-strength support structure that will not deform during pile driving. The support frame 31 includes: a top plate 311, a bottom plate 312, and a support member 313. The shapes of the top plate 311 and the bottom plate 312 correspond to the shape of the pile 1. If the pile 1 is a square pile, then the top plate 311 and the bottom plate 312 are also square plates; if the pile 1 is a pipe pile, then the top plate 311 and the bottom plate 312 are also circular plates. Specifically, the top plate 311 and the bottom plate 312 can be made of steel plates. The two ends of the support member 313 are connected to the top plate 311 and the bottom plate 312 respectively. The connection method can be welding or other methods, and the outer edge dimension of the support member 313 is smaller than the outer edge dimension of the top plate 311 and the bottom plate 312. Specifically, the support member 313 can be one or more of the following combinations: a steel cylinder, multiple reinforcing bars arranged in a circumferential array, or multiple steel pipes filled with concrete.

[0031] In other embodiments, the support frame 31 can also be made of high-strength plastic using injection molding. As long as the strength requirements are met, this embodiment does not limit the material and processing technology of the components in the support frame 31.

[0032] The grout storage bag 32 is located on the outside of the support member 313, and its two ends are connected to the first connector 315 on the top plate 311 and the second connector 316 on the bottom plate 312, respectively. The connection points must be sealed to prevent grout leakage. The grout storage bag 32 has a certain degree of expansion and must not rupture or leak grout under grouting pressure. Materials such as polyester, 1 ton cloth, high-strength fiber cloth, and carbon fiber cloth can be used. It can also be coated with rubber, plastic, or film to improve its seepage prevention performance. The grout storage bag 32, top plate 311, first connector 315, bottom plate 312, second connector 316, and support member 313 together form a grout storage cavity. The closed-loop grouting component 33 in each post-grouting device 3 is connected one-to-one with the first grouting pipe 2 of the pile body 11 to inject grout into the grout storage cavity. The shape of the grout storage bag 32 and the final enlarged head can be arbitrary.

[0033] In addition, an end plate 314 is provided on the bottom plate 312 of a post-grouting device 3 located at the bottom end of the pile body 1. The end plate 314 is provided to facilitate pile driving. Furthermore, the bottom plate 312 of the post-grouting device 3 located at the bottom end of the pile body 1 is a solid plate, and openings are reserved at the center of its top plate 311 and the top plate 311 and bottom plate 312 of the other post-grouting devices 3.

[0034] After the precast pile is driven into the ground at the design elevation, grouting is performed on the ground through the first grouting pipe 2. The grout enters the grout storage bag 32 through the first grouting pipe 2 and the closed grouting component 33. As the grout is injected, the grout storage bag 32 continuously expands and enlarges. After the grouting is completed, the grout solidifies and forms an enlarged head structure at the rear grouting device 3, which can increase the contact area between the precast pile and the stratum, and improve the pull-out resistance and bearing capacity of the precast pile.

[0035] Because the top plate 311 and bottom plate 312 are connected together by the support member 313 during the grouting process, their structural strength can resist the vertical grouting pressure. Therefore, the grout storage bag 32 cannot expand upwards or downwards, but only horizontally. Thus, the grouting pressure of this type of precast pile is no longer limited by the pull-out resistance of the pile body 11. The greater the grouting pressure, the larger the expansion volume of the grout storage bag 32, and the larger the contact area between the grout storage bag 32 and the stratum. Ultimately, after the precast pile is completed, its overall pull-out resistance and bearing capacity are stronger.

[0036] In an optional embodiment, the first connector 315 and the second connector 316 are alternately formed with a groove 3151 and a protrusion 3152 along the height direction of the support frame 31.

[0037] For example, the first connector 315 and the second connector 316 are approximately annular, and are alternately formed with grooves 3151 and protrusions 3152 along the height direction of the support frame 31. When the slurry bag 32 is connected to the connector, steel wire rope or steel strand can be used to tighten the groove 3151, and a hoop is provided on the protrusion 3152 and fixed by rivets.

[0038] Of course, this embodiment does not impose specific restrictions on the specific connection method of the slurry storage bag 32. For example, it can be a bonding connection, anchoring connection, or other forms, as long as the slurry storage bag 32 is securely connected to the first connector 315 and the second connector 316 and there is no leakage of slurry.

[0039] In an optional embodiment, the closed grouting component 33 includes: a grouting pipe section 331, a protective pipe section 332, and a sealing component 333. The top end of the grouting pipe section 331 is connected to the top plate 311, and the bottom end is provided with the protective pipe section 332. The upper part of the grouting pipe section 331 is provided with a grout outlet hole 334, and the lower part of the grouting pipe section 331 is provided with a sealing component 333.

[0040] In an optional embodiment, the diameter of the protective pipe section 332 is smaller than the diameter of the grouting pipe section 331, and the protective pipe section 332 is disposed on the side close to the grout storage bag 32.

[0041] In an optional embodiment, a rubber sleeve is fitted around the slurry outlet 334.

[0042] Specifically, the top of the grouting pipe section 331 is fixedly connected to the top plate 311. A grout outlet hole 334 is provided on the upper wall of the protective pipe section 332. A rubber sleeve is installed outside the grout outlet hole 334, acting as a one-way valve to prevent grout backflow. The sealing element 333 can be a rubber plug, located at the lower part of the grouting pipe section 331. During normal grouting, the grout flows out from the grout outlet hole 334, expands the rubber sleeve, and flows into the grout storage bag 32. Due to the function of the sealing element 333, the grout cannot flow out from the bottom of the grouting pipe section 331.

[0043] The protective pipe section 332 is fixedly connected to the bottom end of the grouting pipe section 331. The diameter of the protective pipe section 332 is smaller than that of the grouting pipe section 331, and the protective pipe section 332 is located on the side close to the grout storage bag 32. When blockage occurs during grouting, tools such as steel pipes can be used to break the sealing element 333, allowing the grout to flow out from the bottom end of the grouting pipe section 331. The protective pipe section 332 prevents tools from puncturing the grout storage bag 32.

[0044] In one embodiment, end plate 314 comprises two plates arranged perpendicularly to each other.

[0045] The two plates are arranged in a cross shape, which can guide the precast piles to be driven vertically into the soil to ensure the accuracy of pile driving. At the same time, the cross shape design can reduce the resistance to soil driving by reducing the contact area with the soil, and evenly transmit external force and disperse impact force during hammering or static pressure pile driving, thereby helping to reduce the difficulty of pile driving and construction energy consumption, and ensuring the quality and efficiency of pile driving construction.

[0046] Furthermore, the end plate 314 can be made of various materials that can withstand pile driving pressure, such as steel plate, reinforced concrete structure, and high-hardness plastic. In other embodiments, the end plate 314 can also be in various shapes, such as conical.

[0047] In one embodiment, a second grouting pipe 4 is provided in the pile body 11, and the rear grouting device 3 further includes an open grouting component 34. The two ends of the open grouting component 34 are respectively connected to the top plate 311 and the bottom plate 312, and its top end is connected to the second grouting pipe 4 of the upper pile body 11, and its bottom end is connected to the grouting space at the second grouting pipe 4 or the end plate 314 of the lower pile body 11.

[0048] Specifically, when the pile body 11 is a square pile, the second grouting pipe 4 is also fixed by pre-embedding; when the pile body 11 is a pipe pile, the second grouting pipe 4 can be fixed to the hollow cavity of the pipe pile. The open grouting component 34 is set on the support frame 31, and its two ends are connected to the top plate 311 and the bottom plate 312 respectively. The second grouting pipe 4 and the open grouting component 34 can form an open grouting channel to perform open grouting into the stratum at the bottom of the precast pile. The grout seeps into the surrounding soil, and after the grout solidifies, it can improve the cohesion between the precast pile and the surrounding stratum, further improving the pull-out resistance and bearing capacity of the precast pile.

[0049] In one embodiment, the support member 313 includes: a telescopic sleeve 3131 and a support column 3132. The two ends of the telescopic sleeve 3131 are connected to the top plate 311 and the bottom plate 312 respectively. A plurality of support columns 3132 are arranged at intervals along the circumference of the telescopic sleeve 3131. The telescopic sleeve 3131 can extend and retract along the height direction of the support frame 31 under the drive of external force.

[0050] The telescopic sleeve 3131 can be two-stage or multi-stage. In this embodiment, a two-stage telescopic sleeve 3131 is used. The two-stage telescopic sleeve 3131 includes an inner cylinder and an outer cylinder that are slidably connected. The top end of the inner cylinder is connected to the top plate 311, and the bottom end of the outer cylinder is connected to the bottom plate 312. Support columns 3132 are spaced around the telescopic sleeve 3131 to improve the pressure-bearing performance of the telescopic sleeve 3131.

[0051] Furthermore, after the telescopic sleeve 3131 extends, grout needs to be injected into the middle of the support frame 31 to seal the sleeve connection, so as to ensure that the subsequent closed grouting of the grout storage bag 32 can be carried out smoothly. The grout can be cement grout or concrete, or carbon fiber or steel fiber can be added to the cement grout or concrete.

[0052] Furthermore, the outermost sleeve can be fitted with protruding ribs on its outer wall, while the inner sleeve can have recessed grooves on its outer side. This improves the tensile and pull-out resistance of the post-grouting device 3 after grouting.

[0053] The post-grouting device 3 with telescopic sleeve 3131 is generally applicable to the case where the pile body 1 is a pipe pile, and is generally installed at the bottom end of the precast pile body 1.

[0054] In one embodiment, the post-grouting device 3 further includes a tension cable 35, the two ends of which are connected to the top plate 311 and the bottom plate 312, respectively.

[0055] When the telescopic sleeve 3131 is in the retracted state, the tension cable 35 is also in the retracted state. As the telescopic sleeve 3131 extends, the tension cable 35 gradually straightens. When the telescopic sleeve 3131 is fully extended, the tension cable 35 is also taut. Specifically, the tension cable 35 can be made of steel strand. The tension cable 35 prevents excessive external force from causing the inner and outer cylinders of the telescopic sleeve 3131 to separate and break.

[0056] In one embodiment, the open grouting component 34 includes: a grouting hose 341 and a connector 342. The two connectors 342 are respectively disposed on the top plate 311 and the bottom plate 312. The two ends of the grouting hose 341 are respectively connected to the two connectors 342, and a grouting one-way valve 343 is connected to the connector 342 on the bottom plate 312 of a rear grouting device 3 at the bottom end.

[0057] The grouting hose 341 can adapt to the expansion and contraction of the telescopic sleeve 3131, ensuring the smooth progress of the grouting work.

[0058] In other embodiments, the post-grouting device 3 does not have a telescopic sleeve 3131, and the grouting hose 341 can also be replaced by a rigid pipe like the first grouting pipe 2 and the second grouting pipe 4.

[0059] The construction method of the post-grouting precast pile provided in this embodiment is described below: Specifically, in combination Figures 13 to 15 The construction method is described using pile 11 as an example, which is a square pile: Firstly, as Figure 13 As shown, the precast pile includes two pile body sections 11, two post-grouting devices 3, and a pile tip. First, one post-grouting device 3 at the bottom is connected to one pile body section 11, and then the pile is driven. Then, the other post-grouting device 3 is connected to both pile body sections 11 respectively, and the pile is driven again until the entire precast pile is driven into the ground at the design elevation.

[0060] Then as Figure 14 As shown, grout is injected into the soil through the second grouting pipe 4 and the open grouting component 34, and the grout also flows back onto the outer wall of the precast pile. After the grout solidifies, it can improve the cohesion between the precast pile and the surrounding soil, resulting in better pull-out resistance and bearing capacity of the precast pile.

[0061] Then as Figure 15 As shown, grout is injected into the grout storage bag 32 through the first grouting pipe 2 and the closed grouting component 33, causing the grout storage bag 32 to expand and eventually form an enlarged head structure.

[0062] In other embodiments, the construction steps for the pile body 11 being a pipe pile are the same as when the pile body 11 is a square pile.

[0063] Furthermore, when the pile body 11 is a pipe pile, a telescopic sleeve 45 can be installed in a post-grouting device 3 at the bottom end, as described below. Figures 16 to 20 The construction steps are described below: Firstly, as Figure 16 As shown, the precast pile includes two pile body sections 11, two post-grouting devices 3, and a pile tip. First, one post-grouting device 3 at the bottom is connected to one pile body section 11, and then the pile is driven. Then, the other post-grouting device 3 is connected to both pile body sections 11 respectively, and the pile is driven again until the entire precast pile is driven into the ground at the design elevation.

[0064] Then as Figure 17 As shown, a hammer or round steel bar is used to penetrate the pipe pile and the hollow cavity in the middle of the post-grouting device 3 to strike the bottom plate 312 of the post-grouting device 3, causing the bottom plate 312 and end plate 314 to sink, and the telescopic sleeve 3131 to extend synchronously. This further compacts the soil below.

[0065] Then as Figure 18 As shown, the mandrel or round steel is removed and grout is injected into the hollow cavity of the pipe pile and the post-grouting device 3. Cement grout, cement mortar, concrete, or other grouts can be injected, and carbon fiber or steel fiber can be added to the cement grout, cement mortar, and concrete grouts. After the grout has solidified, the connection of the expansion sleeve 3131 is sealed.

[0066] Then as Figure 19 As shown, grout is injected into the soil through the second grouting pipe 4 and the open grouting component 34, and it also flows back onto the outer wall of the precast pile. After the grout solidifies, it can improve the cohesion between the precast pile and the surrounding soil, resulting in better pull-out resistance and bearing capacity of the precast pile.

[0067] Finally, as Figure 20 As shown, grout is injected into the grout storage bag 32 through the first grouting pipe 2 and the closed grouting component 33, causing the grout storage bag 32 to expand and eventually form an enlarged head structure.

[0068] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A type of post-grouting precast pile, characterized in that, include: The pile body (1) includes one or more sections of pile body (11) arranged in a vertical direction, and a plurality of first grouting pipes (2) are provided in the pile body (11). The post-grouting device (3) is located at the bottom end of the pile body (1) and between two adjacent sections of the pile body (11). The post-grouting device (3) includes a support frame (31), a grout storage bag (32), and a closed grouting component (33). The support frame (31) includes a top plate (311), a bottom plate (312), and a support member (313). The two ends of the support member (313) are connected to the top plate (311) and the bottom plate (312), respectively. The bottom surface of the bottom plate (312) of the post-grouting device (3) located at the bottom end of the pile body (1) is also provided with an end plate (314). The bottom surface of the top plate (311) is provided with a first connecting member (315). The top surface of 312 is provided with a second connector (316). The two ends of the slurry storage bag (32) are connected to the first connector (315) and the second connector (316) respectively. The slurry storage bag (32) is located outside the support (313). The slurry storage bag (32), the top plate (311), the first connector (315), the bottom plate (312), the second connector (316) and the support (313) together form a slurry storage cavity. Multiple closed grouting components (33) are provided on the top plate (311). The feed end of each closed grouting component (33) is connected to a first grouting pipe (2) of the pile body (11) above, and its discharge end is located in the slurry storage cavity.

2. The post-grouting precast pile according to claim 1, characterized in that, The pile body (11) is provided with a second grouting pipe (4), and the post-grouting device (3) further includes an open grouting component (34). The two ends of the open grouting component (34) are respectively connected to the top plate (311) and the bottom plate (312), and its top end is connected to the second grouting pipe (4) of the upper section of the pile body (11), and its bottom end is connected to the grouting space of the second grouting pipe (4) of the lower section of the pile body (11) or the end plate (314).

3. The post-grouting precast pile according to claim 2, characterized in that, The support member (313) includes a telescopic sleeve (3131) and a support column (3132). The two ends of the telescopic sleeve (3131) are connected to the top plate (311) and the bottom plate (312) respectively. A plurality of support columns (3132) are arranged at intervals along the circumference of the telescopic sleeve (3131). The telescopic sleeve (3131) can extend and retract along the height direction of the support frame (31) under the drive of external force.

4. The post-grouting precast pile according to claim 3, characterized in that, The post-grouting device (3) further includes a tension cable (35), the two ends of which are connected to the top plate (311) and the bottom plate (312) respectively.

5. The post-grouting precast pile according to claim 3, characterized in that, The open grouting component (34) includes: a grouting hose (341) and a connector (342). The two connectors (342) are respectively disposed on the top plate (311) and the bottom plate (312). The two ends of the grouting hose (341) are respectively connected to the two connectors (342). The connector (342) on the bottom plate (312) of the post grouting device (3) disposed at the bottom end of the pile body (1) is connected to a grouting check valve (343).

6. The post-grouting precast pile according to claim 1, characterized in that, The closed grouting component (33) includes: a grouting pipe section (331), a protective pipe section (332), and a sealing component (333). The top end of the grouting pipe section (331) is connected to the top plate (311), and the protective pipe section (332) is provided at its bottom end. A grout outlet hole (334) is opened at the upper part of the grouting pipe section (331), and the sealing component (333) is provided at the lower part of the grouting pipe section (331).

7. The post-grouting precast pile according to claim 6, characterized in that, The diameter of the protective pipe section (332) is smaller than the diameter of the grouting pipe section (331), and the protective pipe section (332) is located on the side close to the grout storage bag (32).

8. The post-grouting precast pile according to claim 6, characterized in that, A rubber sleeve is fitted on the outside of the slurry outlet (334).

9. The post-grouting precast pile according to claim 1, characterized in that, The first connector (315) and the second connector (316) are alternately formed with grooves (3151) and protrusions (3152) along the height direction of the support frame (31).

10. The post-grouting precast pile according to claim 1, characterized in that, The end plate (314) comprises two plates arranged perpendicularly to each other.

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