Recyclable precast pile and construction method

Abstract

The invention belongs to the technical field of underground building construction, and particularly relates to a recyclable precast pile and a construction method. The precast pile comprises a pipe pile body, a recoverable prestressed steel assembly and a connecting assembly, the recoverable prestressed steel assembly is arranged on the pipe pile body in a penetrating mode in the axis direction of the pipe pile body, and the recoverable prestressed steel assembly comprises an isolation pipe sleeve and at least one prestressed tendon; the two ends of the prestressed tendons are detachably connected with the pipe pile body through connecting assemblies. According to the precast pile, the prestressed tendons are detachably connected with the pipe pile body through the connecting assemblies, it is ensured that the prestressed tendons can be separated from the connecting assemblies after construction is completed, that is, the prestressed tendons can be released from the pipe pile body through simple operation, material waste in the building industry is reduced, carbon emission is reduced, and the construction efficiency is improved. And the construction industry is promoted to develop in a more sustainable direction.

Description

Technical Field

[0001] The invention belongs to the technical field of underground building construction, and in particular relates to recyclable prefabricated piles and a construction method. Background Art

[0002] In the context of rapid urbanization, efficient use of urban space has become an urgent task. As an important part of underground building structures, foundation pit engineering has made significant progress in design theory, construction methods and management technology, but it still faces many problems. Especially in terms of resource conservation and environmental protection, existing foundation pit support projects often cause resource waste and environmental damage due to the use of a large amount of disposable materials. In particular, traditional reinforced concrete piles, the steel bars inside are difficult to recycle after the construction is completed, which not only leads to resource waste, but also may cause long-term pollution to the underground environment. In addition, although the detachable steel cage technology provides some solutions, the on-site processing requirements, slow construction progress, and environmental issues of electric welding operations are still limitations to its application. Summary of the invention

[0003] The purpose of the present invention is to at least solve the problem that the main reinforcement of the prefabricated pile cannot be recycled. This purpose is achieved through the following technical solutions:

[0004] The first aspect of the present invention provides a recyclable prefabricated pile, characterized in that it comprises:

[0005] pipe pile body;

[0006] A recyclable prestressed steel component is disposed in the pipe pile body along the axial direction of the pipe pile body, and the recyclable prestressed steel component includes an isolation sleeve and at least one prestressed tendon, the isolation sleeve is sleeved on the circumferential outer side of the prestressed tendon, and at least one end of the prestressed tendon is located on the outer side of the top of the pipe pile body along the axial direction, and the top faces the slope top of the foundation pit;

[0007] A connection assembly, both ends of the prestressed tendon are connected to the pipe pile body in a detachable manner through the connection assembly.

[0008] According to the recyclable precast pile of the present invention, by arranging at least one end of the prestressed tendon on the outside of the top of the pipe pile body, and the prestressed tendon is detachably connected to the pipe pile body through a connecting assembly, it is ensured that the prestressed tendon can be separated from the connecting assembly after the construction is completed. After the foundation pit support of the precast pile is completed, the prestressed tendon (referring to the main tendon) can be released from the pipe pile body through a simple operation without damaging the pipe pile body or the prestressed tendon itself. Through the above analysis, it can be seen that a recyclable precast pile of the present invention not only solves the technical problem that the main tendons of traditional precast piles cannot be recycled, but also provides a more environmentally friendly and economical construction solution. The application of the present invention is expected to significantly reduce material waste in the construction industry and promote the construction industry to develop in a more sustainable direction. In addition, the implementation of the present invention will also reduce long-term maintenance and replacement costs, providing actual economic benefits for users and builders.

[0009] In addition, the recyclable prefabricated pile according to the present invention may also have the following additional technical features:

[0010] In some embodiments of the present invention, the recyclable prestressed steel component includes prestressed tendons and anchor tendons, one end of the prestressed tendons is inserted into the isolation sleeve from one axial end of the isolation sleeve, the anchor tendons are fixedly connected to the pile body, the connecting assembly includes a connector, the connector is abutted against the other axial end of the isolation sleeve, and the prestressed tendons are connected to the anchor tendons through the connector.

[0011] In some embodiments of the present invention, the end of the prestressed tendon located outside the top of the isolation sleeve is the first end, and the connecting assembly further includes a first nut, and the first end is connected to the pipe pile body through the first nut.

[0012] In some embodiments of the present invention, the anchor bar and the pipe pile body are an integrally formed cast structure.

[0013] In some embodiments of the present invention, the number of the prestressed tendon is one, and the prestressed tendon passes through the isolation sleeve, the prestressed tendon has a first end and a second end, the first end is located on the top outside of the isolation sleeve, and the second end is located on the bottom outside of the isolation sleeve, the connecting assembly includes a first nut and a second nut, the first end is connected to one end of the pipe pile body through the first nut, and the second end is connected to the other end of the pipe pile body through the second nut.

[0014] In some embodiments of the present invention, lubricating grease and / or an adhesive retarder are filled between the isolation sleeve and the prestressed tendons.

[0015] In some embodiments of the present invention, there are multiple recyclable prestressed steel components, and the multiple recyclable prestressed steel components are evenly and symmetrically arranged along the circumference of the pipe pile body.

[0016] In some embodiments of the present invention, the prefabricated pile further comprises an end plate, which is located at the top of the tubular pile body and is sandwiched between the first nut and the top of the tubular pile body.

[0017] A second aspect of the present invention provides a construction method of a recyclable precast pile, which is used for construction according to the above-mentioned precast pile, comprising the following steps:

[0018] Processing the prefabricated piles in a factory, and tensioning and locking the prestressed tendons;

[0019] Lowering the prefabricated piles to the designed elevation according to the static pressure method or the hammer method;

[0020] Carry out the crown beam construction and isolate and protect the prestressed tendons exposed on the top of the pipe pile body;

[0021] Carry out earth excavation and anchor construction layer by layer until the designed trench bottom is reached;

[0022] After the main structure construction reaches or exceeds the ground elevation, the fertilizer tank is backfilled;

[0023] The prestressed tendons are carried out.

[0024] In some embodiments of the present invention, the construction method further comprises recycling the prefabricated piles, and the step of recycling the prefabricated piles comprises:

[0025] The prefabricated pile is slowly pulled out together with the prestressed tendons to gradually form a pile hole;

[0026] Backfill material is simultaneously injected through the hole in the center of the precast pile to fill the pile hole until the precast pile is completely removed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference numerals are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0028] Figure 1 Schematically showing a structural diagram of a prefabricated pile according to an embodiment of the present invention;

[0029] Figure 2 Schematically showing a first perspective view of a precast pile according to an embodiment of the present invention;

[0030] Figure 3 Schematically shows a cross-sectional structural diagram of a prefabricated pile without an expanded body portion according to a first embodiment of the present invention;

[0031] Figure 4 A schematic diagram of a first perspective view of a prefabricated pile without an enlarged body portion according to a first embodiment of the present invention is shown, and three pile types a, b, and c are given;

[0032] Figure 5 for Figure 3 A partial enlarged view of the middle A;

[0033] Figure 6 for Figure 3 A partial enlarged view of point B in the middle;

[0034] Figure 7 The cross-sectional structure diagram of the prefabricated pile without the enlarged body portion according to the second embodiment of the present invention is schematically shown;

[0035] Figure 8 for Figure 7 A partial enlarged view of point C in the middle;

[0036] Fig. 9 The schematic diagram of the structure of the prefabricated piles according to the present invention when arranged in a foundation pit is shown;

[0037] Fig.10 The structural schematic diagram of the prefabricated piles constructed by triaxial cement-soil mixing according to the present invention is schematically shown.

[0038] The reference numerals are as follows:

[0039] 100. Precast piles;

[0040] 10. Pipe pile body; hole, 101; 20. Prestressed tendon 20; 21. Anchor tendon; 30. Connecting assembly; 31. First nut; 32. Second nut; 33. Anchor piece; 34. Connector; 40. Expanded body; 50. Isolation sleeve;

[0041] 201. Top of foundation pit slope; 202. Bottom of foundation pit; 203. Three-axis cement-soil mixing piles; 300. Anchor rods. DETAILED DESCRIPTION

[0042] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0043] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0044] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0045] For ease of description, spatial relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figure, such as "inside", "outside", "inner side", "outer side", "below", "below", "above", "above", etc. Such spatial relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure is turned over, then the elements described as "below other elements or features" or "below other elements or features" will subsequently be oriented as "above other elements or features" or "above other elements or features". Therefore, the example term "below..." can include both above and below orientations.

[0046] like Figures 1 to 8As shown, according to an embodiment of the present invention, a recyclable prefabricated pile 100 is proposed, comprising a pipe pile body 10, a recyclable prestressed steel component and a connecting component 30, wherein, along the axial direction of the pipe pile body 10, the recyclable prestressed steel component comprises an isolation sleeve 50 and at least one prestressed tendon 20, the isolation sleeve 50 is sleeved on the circumferential outer side of the prestressed tendon 20, at least one end of the prestressed tendon 20 is located on the outer side of the top of the pipe pile body 10 along its axial direction, and the top is used to face the slope top of the foundation pit, and both ends of the prestressed tendon 20 are connected to the pipe pile body 10 in a detachable manner through the connecting component 30.

[0047] According to the precast pile 100 of the present invention, by arranging at least one end of the prestressed tendon 20 on the outside of the top of the pipe pile body 10 and exposing it on the top of the foundation pit, the prestressed tendon 20 is connected to the pipe pile body 10 in a detachable manner through the connecting assembly 30, ensuring that the prestressed tendon 20 can be separated from the connecting assembly 30 after the construction is completed. This design not only simplifies the disassembly process of the prestressed tendon 20, but also ensures the flexibility and maintainability of the construction. After the foundation pit support of the precast pile is completed, the main reinforcement can be released from the pipe pile body 10 by simple operation without damaging the pipe pile body 10 or the prestressed tendon 20 itself. Through the above analysis, it can be seen that a recyclable precast pile 100 of the present invention not only solves the technical problem that the main reinforcement of the traditional precast pile cannot be recycled, but also provides a more environmentally friendly and economical construction solution. The application of the present invention is expected to significantly reduce material waste in the construction industry, reduce carbon emissions, and promote the construction industry to develop in a more sustainable direction. In addition, the implementation of the present invention will also reduce long-term maintenance and replacement costs, providing actual economic benefits for users and builders. The design concept and implementation strategy of the precast pile 100 will have a positive impact on the material utilization and construction methods of the entire construction industry.

[0048] In some embodiments, the precast pile 100 further includes an expanded portion 40 , and the pile body 10 is received in the expanded portion 40 .

[0049] like Figure 3As shown, in some embodiments, the recyclable prestressed steel component includes only one prestressed tendon 20, the prestressed tendon 20 completely penetrates the isolation sleeve 50, the isolation sleeve 50 completely penetrates the pipe pile body 10, the two ends of the prestressed tendon 20 are respectively arranged outside the top and bottom of the pipe pile body, the first end is arranged at the top, and the second end is arranged at the bottom, and both ends are connected to the pipe pile body through a connecting assembly, the connecting assembly includes a first nut 31 and a second nut 32, the first end is connected to the top end of the pipe pile body 10 through the first nut 31, and the second end is connected to the bottom of the pipe pile body 10 through the second nut 32. After the prefabricated pile 100 is supported, the nut on the top of the prestressed tendon 20 is first unscrewed, and then the prestressed tendon 20 is rotated to separate the nut at the bottom from the prestressed tendon 20, and then the prestressed tendon 20 can be taken out and recycled.

[0050] In other embodiments, the recyclable prestressed steel component includes a prestressed tendon 20 and an anchor tendon 21, one end of the prestressed tendon 20 is inserted into the isolation sleeve 50 from the axial end of the isolation sleeve 50, the anchor tendon 21 is fixedly connected to the pile body 10, and the connection assembly 30 includes a connector 34, the connector 34 is abutted against the other axial end of the isolation sleeve 50 (that is, the connector 34 does not enter the isolation sleeve 50), and the prestressed tendon 20 located in the isolation sleeve 50 is connected to the anchor tendon 21 through the connector 34.

[0051] It can be understood that the prestressed tendons 20 are main tendons, the anchor tendons 21 are auxiliary tendons, the prestressed tendons 20 are exposed from the top of the foundation pit, and the anchor tendons 21 are arranged toward the bottom of the foundation pit. As the main tendons, the prestressed tendons 20 usually have a larger diameter and higher strength because they need to withstand greater tension and ground loads. The part of the slope top exposed from the foundation pit is usually used to connect with other structures, such as a crown beam or a ground structure, to provide the main bearing capacity of the entire foundation pit support system. The location of the main tendons and the exposed part allow the prestressed tendons 20 to be recovered after the foundation pit operation is completed, so that it is easy to remove it from the connection point and carry out subsequent treatment or reuse. As auxiliary tendons, the anchor tendons 21 are mainly arranged toward the bottom of the foundation pit. This configuration helps to provide support from the bottom to the top, enhance the stability of the entire foundation pit, and is particularly effective in deeper foundation pits. The auxiliary tendons can help disperse the soil pressure and reduce the pressure and deformation of the side walls of the foundation pit. By extending to the bottom of the foundation pit, the auxiliary tendons also help to provide additional anchoring in softer or unstable strata, thereby ensuring the safety of the foundation pit.

[0052] Specifically, the end of the prestressed tendon 20 located outside the top of the isolation sleeve 50 is the first end, and the connecting assembly 30 includes a first nut 31. The first end is connected to one end of the pipe pile body 10 through the first nut 31. The first nut 31 is located at the first end of the prestressed tendon 20 and is fastened to one end of the pipe pile body 10. The first nut 31 is used to adjust the initial tension of the prestressed tendon 20 during the installation process of the precast pile 100 and maintain the tension during operation.

[0053] like Figure 1 As shown, it can be understood that the anchor bar 21 and the pipe pile body 10 are an integrally formed cast structure, and the pipe pile body 10 directly provides anchoring force for the anchor bar 21.

[0054] like Figure 7 and Figure 8 As shown, it can be understood that there can also be the following embodiments, the end of the anchor bar 21 located at the bottom of the isolation sleeve 50 is the second end, the connection assembly 30 also includes an anchor 33, and the second end is connected to the pipe pile body 10 through the anchor 33. Combined with the first nut 31 in the above embodiment, a complete embodiment is formed, the anchor bar 21 has one end connected to the connector 34 and a second end, the end connected to the connector 34 is connected to the prestressed bar 20 through the connector 34, and the second end is connected to the pipe pile body 10 through the anchor 33. The second end of the anchor bar 21 is stably connected to the other end of the pipe pile body 10 through the anchor 33. The anchor 33 is designed to provide a strong anchoring function to ensure that the anchor bar 21 will not loosen or shift even under long-term or high-load conditions.

[0055] Specifically, the anchor 33 is a concrete block or a concrete fixing seat, which is formed at the connection between the end of the anchor bar 21 and the pipe pile body 10. The main purpose of this design is to use the strength and structural stability of concrete to bear the tension applied by the prestressed tendons 20. The concrete anchor 33 can be made by prefabrication. The prefabricated concrete anchor 33 is manufactured in a controlled environment to ensure that the quality and strength meet the engineering requirements. The steps of pre-supporting the anchor 33 can be first, designing the size, shape and strength of the anchor 33 according to the engineering requirements and load requirements. This usually involves calculations and simulations by structural engineers to ensure that the anchor 33 can withstand the expected forces and environmental impacts; secondly, making a suitable mold; then, the second end of the pipe pile body 10 that can expose the anchor bar 21 is placed in the mold, concrete is prepared according to the design requirements to ensure that it reaches the required strength and durability, and the concrete is poured into the mold, and a vibrator is used to ensure that the concrete fills the mold and forms a seamless connection around the second end. The high compressive strength of the concrete provides a solid anchor point for the anchor bar 21, which helps to bear a large tension, thereby improving the stability and pull-out resistance of the entire pile body. The durability of concrete ensures that the anchor 33 can resist the influence of environmental factors such as humidity, temperature changes and chemical corrosion in long-term service, maintaining the integrity and functionality of the structure. The use of precast concrete anchors 33 allows most of the production and quality control work to be completed in the factory in advance, shortening the on-site construction time and reducing the complexity and cost of on-site construction. By using concrete as the anchor 33 material, its structural properties can be effectively utilized to support the high-tension anchor bars 21, providing a sturdy and reliable anchoring solution for the precast pile 100. This solution is suitable for various geological conditions and environments, and is particularly suitable for heavy-duty engineering projects that require long-term stable support.

[0056] It is understood that the isolation sleeve 50 is a tubular component that is sleeved on the prestressed tendon 20. Its function is to protect the prestressed tendon 20 from direct contact with the soil layer or other corrosive substances, and at the same time, when the prestress is applied, it allows the prestressed tendon 20 to slide freely therein to evenly transfer the prestress. The isolation sleeve 50 is usually made of corrosion-resistant materials, such as plastic, stainless steel, or metal coated with an anti-corrosion layer. Before the prestressed tendon 20 is inserted into the isolation sleeve 50 of the pile body 10, the prestressed tendon 20 is first inserted into the isolation sleeve 50. The length of the isolation sleeve 50 is usually matched with the length of the prestressed tendon 20 in the pile body 10. The isolation sleeve 50 provides a protective layer for the prestressed tendon 20, isolating it from contact with moisture and corrosive chemicals, thereby significantly extending the life and maintenance cycle of the prestressed tendon 20. Since the prestressed tendon 20 can slide freely in the isolation sleeve 50, the tension can be more evenly transmitted along the prestressed tendon 20, improving the stability and bearing capacity of the overall structure. By pre-installing the isolation sleeve 50 and pre-filling the concrete, the on-site construction process is simplified, the complicated operations during the construction are reduced, and the consistency and controllability of the construction quality are ensured.

[0057] It is understandable that lubricating grease and / or a slow-adhesive agent are filled between the isolation sleeve 50 and the prestressed tendon 20 (including the prestressed tendon 2021), and lubricating grease can be filled between the isolation sleeve 50 and the prestressed tendon 20. Lubricating grease is mainly used to reduce the friction of the prestressed tendon 20 during the tensioning process, allowing the prestressed tendon 20 to slide freely in the isolation sleeve 50, thereby transmitting the prestress more evenly. Lubricating grease should be selected as high-performance and long-lasting to ensure that its lubricity is maintained in long-term applications. The slow-adhesive agent is used to control the adhesion between the prestressed tendon 2021 and the isolation sleeve 50. It usually has the characteristics of slow hardening, which can allow the prestressed tendon 2021 and the anchoring tendon 21 to slide in the isolation sleeve 50 for a certain period of time, and then gradually solidify, which helps to control the long-term stability of the prestress. Before the prestressed tendon 20 is implanted in the isolation sleeve 50, lubricating grease is applied first. After the prestressed tendon 20 is installed, the filling material can be supplemented through the injection port of the isolation sleeve 50 to ensure that there is no gap and the distribution is uniform. The use of lubricating grease can significantly reduce the friction resistance of the prestressed tendons 20 during the tensioning process, so that the tension is more evenly distributed along the tendons, thereby improving the overall performance of the structure.

[0058] In some embodiments, the precast pile 100 further includes an end plate, which is located at the top of the pipe pile body 10 and is sandwiched between the first nut 31 and the top of the pipe pile body 10. The end plate is designed as a solid metal plate, which is located between the first end of the prestressed tendon 20 and the first nut 31. The main function of the end plate is to serve as a pressure distribution plate between the prestressed tendon 20 and the pipe pile body 10, which helps to disperse the force transmitted from the prestressed tendon 20 to the pipe pile body 10 and avoid local stress concentration. The shape of the end plate is consistent with the shape of the end of the pipe pile body 10. The end plate is usually made of high-strength steel to ensure sufficient strength and rigidity to withstand the high tension of the prestressed tendon 20. The thickness and size of the end plate are determined according to the diameter of the prestressed tendon 20 and the expected tension to ensure that it can work effectively. In addition, the end plate is sandwiched between the first end of the prestressed tendon 20 and the first nut 31 during installation. This configuration allows the end plate to directly withstand the tension from the prestressed tendon 20, while being fixed by the nut to ensure the stability of the connection. Gaskets or other buffer materials may be used between the end plate and the pile body 10 to further reduce wear and protect the contact surface between the end plate and the pile body 10. The end plate can effectively disperse the tensile force of the prestressed tendons 20 and avoid excessive stress concentration at the connection point, which helps to improve the structural stability and durability of the entire pull-out pile.

[0059] In some embodiments, the volume of the expanded body 40 is greater than the volume of the pipe pile body 10. The expanded body 40 is generally designed as an enlarged structure at the bottom of the pipe pile, and can be in different shapes, such as round, square or with a specific contour, in order to increase the contact area with the soil layer, thereby improving the pull-out resistance. The material of the expanded body 40 can be concrete, reinforced concrete or other suitable structural materials, which are selected according to geological conditions and structural requirements. Specifically, the expanded body 40 is cast on site. Since the volume of the expanded body 40 is greater than that of the pipe pile body 10, the bearing area and friction area of ​​the pile foundation are greatly increased, and the pull-out resistance is significantly improved. This is particularly important in soft soil layers or underwater projects, and can effectively prevent the structure from moving or flipping due to buoyancy. The enlarged expanded body 40 can more effectively disperse loads and stresses, reduce local instability of the soil layer and uneven settlement of the structure, and increase the stability of the entire pull-out pile. In summary, through the large-volume expanded body 40, the pull-out pile can provide reliable support in demanding environments, such as important structures such as marine engineering, bridge foundations and high-rise buildings, ensuring their stability and safety in long-term operation.

[0060] It is understandable that the material of the expanded body 40 can be a premixed fluidized cement soil mixture, a cement mortar mixture, fine stone concrete or jet-mixed cement soil. Among them, the premixed fluidized cement soil mixture is suitable for occasions that require rapid construction and initial strength. The material has good fluidity and is easy to pour, and is suitable for complex or narrow foundation conditions; the cement mortar mixture can provide better density and bearing capacity, and is suitable for structural foundations that bear medium loads; fine stone concrete, due to its smaller aggregate size, is suitable for the expanded body 40 that requires higher surface quality and structural tightness; jet-mixed cement soil is suitable for situations where foundation conditions are uneven or soil quality needs to be improved, and jet mixing can ensure that the material is fully mixed with the original foundation soil. The selected expanded body material combined with the construction method can significantly improve the foundation bearing capacity and stability of the pull-out pile, especially in soft soil, by increasing the pull-out capacity by expanding the bottom area.

[0061] It is understandable that the construction process of the expansion part 40 can be a long spiral pressure grouting method, a rotary drilling hole grouting method or a jet mixing cement soil method. Among them, the long spiral pressure grouting method is suitable for the expansion construction that needs to go deep into the foundation. Continuous pouring is carried out through a long spiral drill to effectively control the pouring process and reduce material stratification and voids; the rotary drilling hole grouting method is suitable for the construction of a large diameter expansion part 40. Concrete is poured after the rotary drilling rig drills the hole, which is suitable for harder geological conditions. The jet mixing cement soil method uses high-pressure jetting technology to mix cement slurry with the soil layer on site, improve the soil quality and form an expansion at the same time, which is suitable for foundation reinforcement and environmental remediation projects. The diverse material selection and construction technology enable the pull-out pile system to adapt to various geological and environmental conditions, provide targeted solutions, and meet the specific needs of different projects.

[0062] It is understandable that the method of implanting the pipe pile body 10 can be static pressure method or hammering method. The static pressure method is suitable for areas with strict noise and vibration requirements, and the pipe pile is pressed into the ground by static force to reduce the impact on the surrounding environment. The hammering method is suitable for occasions with hard foundations. The pipe pile is penetrated through the hard ground by hammering. Although the speed is fast, it may generate large noise and vibration.

[0063] In some embodiments, there are multiple recyclable prestressed steel components, and the multiple recyclable prestressed steel components are evenly and symmetrically arranged along the circumference of the pipe pile body 10. In this embodiment, only the recyclable prestressed steel components are inserted into the pipe pile body 10. The multiple recyclable prestressed steel components are evenly and symmetrically arranged along the circumference, which can effectively disperse the pull-out force and enhance the overall pull-out resistance of the pull-out pile. The evenly and symmetrical arrangement makes the force on the pipe pile body 10 more uniform, reduces local stress concentration, and prolongs the service life.

[0064] In other embodiments, there are multiple recyclable prestressed steel components, and the multiple recyclable prestressed steel components are evenly and symmetrically arranged along the circumference of the pipe pile body 10. However, in this embodiment, the pipe pile body 10 is not only penetrated by recyclable prestressed steel components, but also penetrated by prestressed steel bars in the prior art. The recyclable prestressed steel components correspond to the prestressed steel bars one by one and are arranged at intervals. The combined use of recyclable prestressed steel components and prestressed steel bars in the prior art significantly enhances the pull-out resistance of the prefabricated pile 100, enabling it to withstand higher pull-out forces. The prestressed steel bars and recyclable prestressed steel components correspond to each other one by one and are arranged at intervals, providing multiple reinforcements and further improving the overall strength and rigidity of the pipe pile body 10.

[0065] It is understood that the first nut 31 and the second nut 32 have a self-locking function, which can be achieved by designing a thread of a specific shape, such as a sawtooth or wedge-shaped thread. Such a self-locking thread can effectively prevent the nut from rotating and loosening under load. Alternatively, an additional locking device, such as a reverse locking nut or a locking pin, can be introduced to ensure that the nut can be reliably locked in place after the tension reaches the required prestress. It is possible to consider using nylon plugs or other anti-loosening devices, which generate additional friction between the threads to prevent the nut from automatically loosening under vibration or long-term load.

[0066] It is understandable that the first nut 31 and the second nut 32 are convex in design, which will bring additional structural advantages and functionality to the tensioning and locking of the prestressed tendons 20 and the anchoring tendons 21, respectively. Convex nuts usually have a larger contact area and improved mechanical properties, and such a design helps to more effectively transmit and disperse pressure while improving the stability of the connection. Convex nuts usually have a protruding dome-shaped or hemispherical head, which can provide a larger contact area and reduce material fatigue or damage caused by concentrated tension. The raised portion of the nut can effectively disperse the forces generated by the prestressed tendons 20 and the anchoring tendons 21 during tensioning, helping to evenly transmit these forces to the pile structure.

[0067] It is understandable that if Figure 4 As shown, there are three types of prefabricated piles 100, namely, a, b, and c. Different pile types can be selected according to different construction scenarios.

[0068] Furthermore, if Figure 4 In the pile type of the precast pile 100 shown in a, a hole 101 penetrating the top and bottom of the precast pile 100 is opened in the center of the pipe pile body 10 of the precast pile 100, and the hole 101 is coaxially arranged with the pipe pile body 10.

[0069] like Figures 9 and 10As shown, this embodiment also provides a construction method of a recyclable prefabricated pile 100, which is used to construct according to the above-mentioned prefabricated pile 100, comprising the following steps:

[0070] The prefabricated piles 100 are processed in the factory, and the prestressed tendons 20 are tensioned and locked;

[0071] Lower the precast pile 100 to the designed elevation by static pressure method or hammering method;

[0072] Carry out the crown beam construction and isolate and protect the exposed prestressed tendons 20;

[0073] Carry out earth excavation and anchor construction layer by layer until the designed trench bottom is reached;

[0074] After the main structure construction reaches or exceeds the ground elevation, the fertilizer tank is backfilled;

[0075] The prestressed tendons 20 are recovered.

[0076] In addition, this embodiment also provides a construction method of a recyclable prefabricated pile 100, which is used to construct the prefabricated pile 100, comprising the following steps:

[0077] Construct water-stop curtains by mixing method or high-pressure jet spraying method;

[0078] Lower the precast pile 100 to the designed elevation by static pressure method or hammering method;

[0079] Tensioning and locking the prestressed tendons 20;

[0080] Carry out the crown beam construction and isolate and protect the exposed prestressed tendons 20;

[0081] Carry out earth excavation and anchor construction layer by layer until the designed trench bottom is reached;

[0082] After the main structure construction reaches or exceeds the ground elevation, the fertilizer tank is backfilled;

[0083] The prestressed tendons 20 are recovered.

[0084] like Fig. 9 As shown, the precast pile 100 has been completely inserted into the foundation pit, the top of the precast pile 100 is flush with the foundation pit slope top 201, and part of the precast pile 100 is inserted under the foundation pit bottom 202.

[0085] Specifically, the method of constructing the water-stop curtain according to the stirring method is to use a drill rod with stirring blades for stirring. The drill rod can be single-axis, double-axis or multi-axis (such as three-axis, such as Fig.10The three-axis cement soil mixing pile 203 shown in the figure is used to improve the uniformity and efficiency of mixing. Cement slurry is usually used as a mixing additive. The cement slurry is hardened after being fully mixed with the soil layer to form a solidified soil body with waterproof function. The construction process is that the drill rod is drilled deep into the ground to reach the designed depth, and then the drill rod is rotated and stirred while being pulled to ensure that the additive is evenly distributed in the soil layer. The method of constructing a water-stop curtain according to the high-pressure rotary spraying method is to use a high-pressure rotary spraying machine to spray cement slurry into the soil layer at high pressure through a rotating nozzle. The nozzle can adjust the direction and intensity of the high-pressure water flow as needed. The construction process is to first drill the rotary spraying drill rod into a predetermined depth, then start the high-pressure pump, and spray cement slurry around through a rotating nozzle. During the spraying process, the drill rod is slowly lifted and rotated at the same time to form a solidified soil column with a larger diameter. In addition, in addition to cement, other chemical additives are sometimes added to improve the performance of the soil column.

[0086] Specifically, the static pressure method uses static load to push the precast pile 100 into the foundation. This method is particularly suitable for areas that are sensitive to environmental interference, such as city centers, residential areas, or places near sensitive facilities. The hammer method uses a heavy hammer (diesel hammer, pneumatic hammer or hydraulic hammer) to periodically hit the top of the pile to drive the pile body into the ground. This method is suitable for a variety of soil types, especially harder strata.

[0087] Specifically, the steps of tensioning and locking the prestressed tendon 20 include: first, ensuring that the prestressed tendon 20 is correctly placed in the prefabricated pile 100 according to the design requirements, and fixed in the appropriate position of the pile body through the isolation sleeve 50 or directly. Use a special tensioning device, such as a hydraulic tensioner, connected to the first end of the prestressed tendon 20. These devices can accurately control the tension applied to the tendon. Gradually increase the tension according to the design requirements until a predetermined force value is reached. This process requires strict monitoring to ensure that the tension is uniform and meets technical specifications. During the tensioning process, a monitoring device such as a stress sensor or a strain gauge is used to detect the stress state of the prestressed tendon 20 to ensure that the elastic limit of the prestressed tendon 20 is not exceeded to avoid permanent deformation or damage. After the required tension is reached, a fastening device (such as a first nut 31) is used to fix the position of the prestressed tendon 20. The fastening device must be able to reliably withstand long-term tension without slipping. After the anchoring is completed, the tension of the prestressed tendon 20 is checked again to ensure its stability and consistency. Fine-tune when necessary to adapt to changes that may occur during construction. To prevent the anchor points from corrosion or damage, the anchor system should be properly protected, such as applying an anti-corrosion layer or installing a protective cover.

[0088] It is understandable that in order to avoid deformation or cracking of the pile body of the precast pile 100 caused by uneven tensioning, the correct tensioning sequence should be adopted to prevent structural cracks or uneven settlement caused by uneven loading. First, according to the structural design requirements, the layout and position of the prestressed tendons 20 and the predetermined tension of each prestressed tendon 20 are clarified. The prestressed tendons 20 are grouped according to their positions and functions in the structure, and each group of prestressed tendons 20 will be tensioned within a specific time period. The tensioning sequence is determined based on the symmetry, construction convenience and structural balance of the structure. Generally, tensioning is performed from the center of the structure to the outside or from one end to the other to maintain the balance of the structure. The tensioning of the prestressed tendons 20 usually needs to be carried out in several stages, and one or more groups of prestressed tendons 20 are tensioned in each stage. After each tensioning, the response of the structure needs to be evaluated, such as monitoring of displacement and stress. In order to avoid causing asymmetry and possible offset of the structure, the tensioning of the tendons in relative positions should be performed alternately. For example, in a bridge project, the prestressed tendons 20 on the left can be tensioned first, then the prestressed tendons 20 on the right, and so on. The tension applied should be strictly controlled each time to ensure that it reaches but does not exceed the tension value required by the design. Use high-precision tensioning equipment and real-time monitoring systems to ensure the accuracy of the tensioning force. The correct tensioning sequence is especially important for prestressed concrete structures because it is related to the final performance and safety of the structure.

[0089] Specifically, the method for crown beam construction is as follows: first, before pouring the crown beam, tie the steel mesh of the crown beam, including longitudinal and transverse steel bars. Ensure that the steel bars are in the correct position and consistent with the design drawings to ensure the bearing capacity and crack resistance of the crown beam. Use spacers and supports to ensure that the coverage depth of the steel bars meets the requirements of the specifications. Install the crown beam formwork, check the stability and sealing of the formwork, and ensure that no leakage or deformation of the formwork occurs during the pouring process. Check the horizontality and verticality of the formwork to ensure the geometric size and position of the crown beam are accurate. Finally, select a suitable concrete mix ratio, which usually requires high strength and good fluidity in order to fill the entire formwork and bypass the steel bars and prestressed tendons 20. Use a vibrator to fully vibrate the concrete to eliminate bubbles and ensure good bonding between the concrete and the steel bars.

[0090] Specifically, isolating and protecting the exposed prestressed tendons 20 includes installing isolation sleeves 50. These isolation sleeves 50 can not only protect the prestressed tendons 20 from erosion by the external environment, but also prevent them from bonding with the crown beam concrete, ensuring that the length and diameter of the isolation sleeves 50 are suitable for the prestressed tendons 20 and remain stable during the entire construction and use period. In addition, the ports of the isolation sleeves 50 are sealed with non-shrinkage grouting materials or special sealants to prevent moisture and other corrosive substances from entering the interior of the isolation sleeves 50. Waterproof coatings or other protective layers are applied to the portion of the isolation sleeves 50 that contacts the crown beam to further enhance the protective effect.

[0091] Specifically, earth excavation and anchor construction are carried out step by step until the designed trench bottom is reached. The partial earth excavation adopts the method of layered or zoned excavation, gradually deepening from top to bottom, and stabilizes the soil layer after each excavation to a certain depth. This method can reduce the impact on the surrounding environment and prevent foundation pit collapse. The length, diameter, layout and inclination of the anchor 300 are designed according to the structural and geological conditions. The position of each anchor 300 should be accurately calculated to ensure that its support effect is maximized.

[0092] It is understandable that the inclination angle range of anchor construction is between 10° and 15°. The use of an inclination angle of 10° to 15° during anchor construction can more effectively resist the sliding force along the side wall of the foundation pit. This angle setting helps to disperse the shear force of the soil or rock, reduce the impact of vertical pressure on the anchor point, and thus enhance the overall stability of the foundation pit or slope.

[0093] Specifically, after the construction of the main structure reaches or exceeds the ground elevation, the fertilizer trough is backfilled. The steps of backfilling the fertilizer trough are as follows: first, before starting backfilling, a detailed structural and geological assessment is carried out to ensure that all supporting structures (such as supporting walls, anchor rods 300, etc.) are stable and have no obvious damage or deformation. Clean the fertilizer trough area and remove any construction waste, debris or water accumulation to ensure that the backfill material can be evenly laid. Secondly, the excavated soil layer is usually used, but it must be ensured that the soil layer is suitable for backfilling and is not polluted. Sometimes it may be necessary to use screened and treated soil layers or specific engineering fillers to ensure compaction and drainage. In some cases, a certain proportion of sand, gravel or other improved materials may also be added to improve the bearing capacity and stability of the soil layer. Then, the backfilling process should be carried out in layers, and the thickness of each layer is usually controlled at 20 to 30 cm. Each layer is laid, and compaction is carried out to ensure that the soil layer is dense and reduce future settlement. Use a roller or a vibrating plate to compact each layer of soil. In moisture-sensitive areas, the moisture content of the backfill soil needs to be controlled to avoid being too wet or too dry. Finally, after all the backfill work is completed, the final ground leveling is carried out to ensure that the site reaches the expected elevation and slope. If necessary, further surface treatment can be carried out, such as laying turf, installing drainage systems or landscaping.

[0094] In some embodiments, the prestressed tendons 20 can be recycled after the fertilizer tank is backfilled, and the steps include:

[0095] Release the prestress on the prestressed tendons 20 one by one, and remove the connecting assembly 30;

[0096] Rotate the prestressed tendon 20 in the opposite direction to separate the prestressed tendon 20 from the connector 34;

[0097] Pass the upper part of the prestressed tendon 20 through the rectangular crossbeam in the hanging basket, and lock the upper part of the prestressed tendon 20 with the hanging basket;

[0098] The hanging basket and the prestressed tendons 20 are hoisted together and recovered.

[0099] It is understood that the steps to disengage the prestressed tendon 20 from the connector 34 are to select a pipe clamp of the appropriate size and type to match the diameter and material of the main bar. The pipe clamp should be able to firmly grasp the main bar without causing damage. Fix the pipe clamp on the main bar, confirm that it is firmly fixed, and then slowly rotate it in the opposite direction. Reverse rotation refers to the opposite direction of installation, usually counterclockwise. Once the bottom of the main bar is successfully separated from the connector 34, slowly unscrew the main bar completely. Ensure that the entire process is smooth and avoid quick pulling or sudden movements, which may cause damage to the main bar or surrounding structures.

[0100] It is understood that during the construction or maintenance of the precast pile 100, the recovery of the prestressed tendons 20 is a key step. First, select a suitable hanging basket to ensure that its design can carry the prestressed tendons 20 and their own weight and is suitable for safe operation in the working environment. Secondly, pass the upper part of the prestressed tendons 20 through the rectangular beam in the hanging basket. Ensure that the prestressed tendons 20 are in the correct position when passing through the beam to maintain balance and avoid unnecessary tension or torsion during the lifting process. Next, use the locking mechanism in the hanging basket (such as bolts, clamps or other fixing devices) to fix the upper part of the prestressed tendons 20 to the hanging basket. Ensure that all locking devices are firmly installed in place and checked to confirm their load-bearing capacity. Then, use a crane or other suitable lifting equipment to slowly lift the hanging basket and the prestressed tendons 20 together. The lifting speed should be kept uniform and avoid sudden movements to prevent swinging or impact forces. Finally, the lifted prestressed tendons 20 and the hanging basket are safely transferred to the predetermined recovery or storage area. During the placement process, it should be ensured that the ground is flat and can withstand heavy loads. Once safely in place, the load on the lifting equipment is gradually released and all locking mechanisms are carefully disengaged to separate the tendons 20 for retrieval.

[0101] In addition, this embodiment also provides another construction method of a recyclable prefabricated pile 100, which is used for construction according to the above-mentioned prefabricated pile 100, and includes the following steps:

[0102] The prefabricated piles 100 are processed in the factory, and the prestressed tendons 20 are tensioned and locked or a water-stop curtain is constructed by a mixing method or a high-pressure rotary spraying method.

[0103] Lower the precast pile 100 to the designed elevation by static pressure method or hammering method;

[0104] Carry out the crown beam construction and isolate and protect the exposed prestressed tendons 20;

[0105] Carry out earth excavation and anchor construction layer by layer until the designed trench bottom is reached;

[0106] After the main structure construction reaches or exceeds the ground elevation, the fertilizer tank is backfilled;

[0107] The prefabricated pile 100 is recovered.

[0108] Furthermore, the precast pile 100 is recovered by tensioning the upper part of the prestressed tendon 20. The steps of recovering the precast pile 100 include:

[0109] The prefabricated pile 100 is slowly pulled out together with the prestressed tendons 20 to gradually form a pile hole;

[0110] The backfill material is simultaneously injected into the pile hole through the hole 101 at the center of the precast pile 100 to fill the pile hole until the precast pile 100 is completely removed.

[0111] It is understandable that during the process of pulling out the precast pile 100, solidified soil, cement slurry and other backfill materials are poured into the pile hole by connecting a pumping pipe to the top of the precast pile 100. This design can ensure that the pile hole is gradually filled with backfill materials while the precast pile 100 is pulled out. Using solidified soil and cement slurry as backfill materials has a good consolidation effect and bearing capacity, can effectively support the side wall of the pile hole, and prevent the pile hole from collapsing.

[0112] It is understandable that the present embodiment emphasizes that the extraction speed of the precast pile 100 should not be too fast, in order to enable the backfill material to fill the pile hole in time. If the extraction speed of the precast pile is too fast, the backfill material may not be filled to the bottom of the pile hole in time, thereby forming a gap in the pile hole. Such a gap may cause the soil around the pile hole to become unstable and damaged when it is subjected to lateral loads in the later stage.

[0113] It is understandable that the key technical point of this embodiment is to prevent the pile hole from being unstable and damaged due to lateral loads (such as foundation soil or other structural loads) by controlling the extraction speed and filling the backfill material in time. Reasonable construction sequence and process help to ensure the stability of the whole process.

[0114] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A recyclable prefabricated pile, characterized in that: include: pipe pile body; A recyclable prestressed steel component is disposed in the pipe pile body along the axial direction of the pipe pile body, and the recyclable prestressed steel component includes an isolation sleeve and at least one prestressed tendon, the isolation sleeve is sleeved on the circumferential outer side of the prestressed tendon, and at least one end of the prestressed tendon is located on the outer side of the top of the pipe pile body along the axial direction, and the top faces the slope top of the foundation pit; A connection assembly, both ends of the prestressed tendon are connected to the pipe pile body in a detachable manner through the connection assembly.

2. The recyclable prefabricated pile according to claim 1, characterized in that: The recyclable prestressed steel component includes prestressed tendons and anchor tendons. One end of the prestressed tendons is inserted into the isolation sleeve from one axial end of the isolation sleeve, and the anchor tendons are fixedly connected to the pipe pile body. The connecting component includes a connector, which is abutted against the other axial end of the isolation sleeve, and the prestressed tendons are connected to the anchor tendons through the connector.

3. The recyclable prefabricated pile according to claim 2, characterized in that: The end of the prestressed tendon located outside the top of the isolation sleeve is the first end. The connection assembly also includes a first nut. The first end is connected to the pipe pile body through the first nut.

4. The recyclable prefabricated pile according to claim 3, characterized in that: The anchoring bar and the pipe pile body are an integrally formed cast structure.

5. The recyclable prefabricated pile according to claim 1, characterized in that: The number of the prestressed tendon is one, and the prestressed tendon passes through the isolation sleeve. The prestressed tendon has a first end and a second end, the first end is located on the outside of the top of the isolation sleeve, and the second end is located on the outside of the bottom of the isolation sleeve. The connecting assembly includes a first nut and a second nut, the first end is connected to one end of the pipe pile body through the first nut, and the second end is connected to the other end of the pipe pile body through the second nut.

6. The recyclable prefabricated pile according to any one of claims 1 to 5, characterized in that: Lubricating grease and / or a retardant is filled between the isolation sleeve and the prestressed tendons.

7. The recyclable prefabricated pile according to any one of claims 1 to 5, characterized in that: There are multiple recyclable prestressed steel components, and the multiple recyclable prestressed steel components are evenly and symmetrically arranged along the circumference of the pipe pile body.

8. The recyclable prefabricated pile according to any one of claims 3 to 5, characterized in that: The prefabricated pile includes an end plate, which is located at the top of the pipe pile body and is sandwiched between the first nut and the top of the pipe pile body.

9. A construction method for recyclable prefabricated piles, characterized in that: The method for constructing a prefabricated pile according to any one of claims 1 to 8 comprises the following steps: Processing the prefabricated piles in a factory, and tensioning and locking the prestressed tendons; Lowering the prefabricated piles to the designed elevation according to the static pressure method or the hammer method; Carry out the crown beam construction and isolate and protect the prestressed tendons exposed on the top of the pipe pile body; Carry out earth excavation and anchor construction layer by layer until the designed trench bottom is reached; After the main structure construction reaches or exceeds the ground elevation, the fertilizer tank is backfilled; Recover the prestressed tendons.

10. The construction method of prefabricated piles according to claim 9, characterized in that: The prefabricated piles are also recovered, and the steps of recovering the prefabricated piles include: The prefabricated pile is slowly pulled out together with the prestressed tendons to gradually form a pile hole; Backfill material is simultaneously injected through the hole in the center of the precast pile to fill the pile hole until the precast pile is completely removed.

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