Prestressed mechanical joint with intermediate sleeve, precast concrete pile and method of connection

Abstract

The application discloses a pre-tightening mechanical joint with an intermediate sleeve, a precast concrete pile and a connecting method, wherein the joint comprises a plug rod provided with a plug; a large nut provided with a receiving cavity; a clamping mechanism arranged in the receiving cavity; a pre-tightening nut in threaded connection with the large nut; and an intermediate sleeve sleeved on the pre-tightening nut and located outside the large nut, wherein the intermediate sleeve is provided with a transmission structure, and the transmission structure is used for driving the intermediate sleeve to rotate by a driving part when the plug is clamped with the clamping mechanism, and then driving the pre-tightening nut to rotate and move along the large nut in the axial direction, so as to lock the plug and the clamping mechanism in the axial direction of the large nut. The pre-tightening mechanical joint disclosed by the application effectively eliminates the gap between the plug and the pre-tightening nut, so that when the precast concrete pile connected by the mechanical joint is subjected to a pulling force, a shearing force or a bending force, the connected part of the precast concrete pile will not crack and generate cracks.

Description

Technical Field

[0001] This invention relates to the field of precast component technology, and in particular to a pre-tightened mechanical joint with an intermediate sleeve, a precast concrete pile, and a connection method thereof. Background Technology

[0002] Most engineering piles (precast piles) are multi-section piles, and the ends of existing precast concrete piles are generally connected quickly between piles using mechanical joints.

[0003] Article 5.1.7 of the "Technical Standard for Prestressed Concrete Pipe Piles" (JGJ / T406-2017) stipulates that for prestressed pipe piles that are strictly required to be free of cracks, the crack control level should be Level I. Article 5.1.8 stipulates that when the pipe pile is under axial tension, the crack control level is Level I; when the pipe pile is under bending, the crack control level is Level II for pipe piles in weakly corrosive environments and above, and Level I for pipe piles in moderately and strongly corrosive environments and above.

[0004] Article 3.4.4 of the "Code for Design of Concrete Structures" (GB50010-2015) stipulates that the stress crack control level of the cross-section of structural members is divided into three levels, and the classification and requirements shall comply with the following provisions:

[0005] Level 1 – For components that are strictly required to be free of cracks, when calculated according to the standard load combination, the concrete at the tension edge of the component should not generate tensile stress.

[0006] Level 2 – For components that are generally required to be free of cracks, when calculated according to the standard load combination, the tensile stress in the concrete at the tension edge of the component should not exceed the standard value of the tensile strength of the concrete.

[0007] Level 3 – Components Allowed to Crack: For reinforced concrete components, when calculating based on the quasi-permanent load combination and considering the long-term effects, the maximum crack width of the component should not exceed the maximum crack width limit specified in Table 3.4.5 of this code. For prestressed concrete components, when calculating based on the standard load combination and considering the long-term effects, the maximum crack width of the component should not exceed the maximum crack width limit specified in Clause 3.4.5 of this code; for prestressed concrete components in Class 2a environments, calculations should also be performed based on the quasi-permanent load combination, and the tensile stress in the concrete at the tension edge of the component should not exceed the standard value of the tensile strength of the concrete. Clause 3.4.5 of this code specifies that the crack control level for prestressed concrete structures is Level 1 in Class 3a and 3b environments, and Level 2 in Class 2b environments. Cracks are not allowed in either Level 1 or Level 2 crack control levels. In Class 2a environments, the crack control level is Level 3, with a maximum crack width limit of 0.1 mm. In Class 1 environments, the crack control level is Level 3, with a maximum crack width limit of 0.2 mm.

[0008] like Figure 21 The diagram shows the first structural form of an existing mechanical joint, including a large nut 2, a small nut 21, a plug rod 1, and a connector 90. One end of the plug rod is threaded to the small nut, and the other end has a plug. The connector is threaded to the large nut, and the end of the connector inside the large nut has multiple elastic clips. The plug is inserted from one end of the connector and can abut against the elastic clips to achieve a snap-fit ​​between the plug rod and the connector. This mechanical joint allows for the rapid connection of two precast concrete piles. However, this type of mechanical joint for connecting precast concrete piles has the following shortcomings: 1. When using this mechanical joint for connecting precast concrete piles, due to factors such as the inclination of the pile end face, the plug rod may be over-inserted into the connector. When this occurs, the precast concrete pile, under the action of tensile force, shear force, or bending force, will cause axial clearance in all or part of the mechanical joint at the pile connection end face, resulting in axial clearance at the precast concrete pile connection, causing cracks to form at the mechanical joint connection. Specifically, for example... Figure 27 The diagram shows the insertion of the plug rod into the connector. After the plug rod is inserted into the connector, an axial gap Δh will be formed between the end of the elastic clip and the stop surface of the plug. As a result, when an external force is applied, a corresponding axial gap will also be generated between the connecting end faces of the precast concrete pile. This makes it impossible to meet the requirements of Article 5.1.7 of the "Technical Standard for Prestressed Concrete Pipe Piles" JGJ / T406-2017, which stipulates that for prestressed pipe piles that are strictly required to be free of cracks, the crack control level should be Level 1; Article 5.1.8 stipulates that when the pipe pile body is under axial tension, the crack control level should be Level 1; when the pipe pile body is under bending... 1. The crack control level for pipe piles in weakly corrosive environments and above is Level II, while the crack control level for pipe piles in moderately and strongly corrosive environments and above is Level I; 2. Since the large nut and the connector, and the small nut and the insert rod are both connected by threads, there will be a certain axial clearance in the threaded connection. Therefore, when the mechanical joint is subjected to pull-out force, the axial clearance of the threaded connection will also cause a corresponding axial clearance between the connecting end faces of the precast concrete pile, further increasing the size of the cracks at the connection of the precast concrete pile, making it impossible to meet the crack control requirements in the "Technical Standard for Prestressed Concrete Pipe Piles" when used for precast concrete pile connections; 3. If Figure 32 As shown, when using this mechanical connector to connect precast concrete piles, there is a problem that the plug of the insert rod is not properly inserted into the connector. That is, when the insert rod is inserted into the connector, the end of the elastic clip does not enter the annular groove of the insert rod. Therefore, the insert rod and the connector cannot be engaged, resulting in the failure of the pile connection.

[0009] like Figure 33The diagram shows a second structural form of an existing mechanical joint, including a large nut 2, a small nut 21, a plug rod 1, an intermediate nut 91, an elastic element 92, and a clip 93. One end of the plug rod is threaded to the small nut, and the other end has a plug. The intermediate nut is threaded to the large nut, and the intermediate nut has a tapered snap-fit ​​surface at one end of the large nut. An elastic element and multiple clips are located within the receiving cavity of the large nut. The elastic element abuts the multiple clips against the tapered snap-fit ​​surface of the intermediate nut. The plug is inserted from one end of the intermediate nut and can compress the elastic element, allowing the plug to pass through the space formed by the multiple clips and snap-fit ​​between the intermediate nut and the plug, thus achieving a rapid connection of two precast concrete piles. However, using this type of mechanical joint for connecting precast concrete piles has the following drawbacks: 1. During the insertion of the plug rod into the intermediate nut, there is a situation where the central axis xx of the plug rod and the central axis yy of the intermediate nut are not aligned. Therefore, if... Figure 33 , Figure 34 and Figure 35 As shown, during the insertion of the plug into the middle nut, the card closer to the plug axis contacts the plug first, while the card further away from the plug axis contacts the plug later. The lower card contacts the plug first and compresses the spring under the action of the plug, while the upper card contacts the plug later. Therefore, the following may occur: Figure 34 The card on one side of the diagram enters between the plug and the center nut, while the card on the other side cannot enter between the plug and the center nut; or, as shown... Figure 35 The different engagement positions of the multiple cards, plugs, and intermediate nuts shown lead to pile connection failure or low connection strength of the mechanical joint. Consequently, when the precast concrete pile is subjected to tensile, shear, or bending forces, axial slippage occurs between the insert rod and the card of the mechanical joint. This results in axial clearance in all or part of the mechanical joint at the pile connection end face, causing cracks to form at the connection point of the precast concrete pile mechanical joint. 2. When the plug is inserted into the intermediate nut and engages with the card, there is no complete wedge-shaped fit between the plug, card, and intermediate nut (at the plug and...). The interaction force between the cards is very small. Therefore, when the insert is subjected to tensile, shear, or bending forces, the plug of the insert will squeeze the card, causing the card to slide axially relative to the plug. As a result, when using this mechanical joint for precast concrete pile connection, the precast concrete pile will experience tensile, shear, or bending forces, causing all or part of the mechanical joint at the pile connection end face to have axial clearance. This will lead to a corresponding axial clearance at the precast concrete pile connection, causing cracks to form at the mechanical joint connection of the precast concrete pile. 3. If Figure 31 As shown, since both the card and the plug have conical or cylindrical contact surfaces, and because the contact position between the card and the plug is uncertain, the contact surfaces of the card and the plug will not completely fit together when they are engaged. Figure 36As shown in the figure, curves Q1 to Q5 represent the cross-sectional radius curves at different positions of the plug's contact surface, and curve J represents the cross-sectional radius curve at a certain position of the card. As shown in the figure, when curve J is at position Q1, curve J is completely in contact with Q1. When curve J is at positions Q2 to Q5, the gap between curve J and curve Q gradually increases. In other words, when the card is at different positions of the plug, the contact state between the card and the plug is different, meaning that it cannot be guaranteed that the contact surface of the card and the contact surface of the plug are completely in contact. In other words, the contact between the card and the plug is line contact. When the mechanical joint is subjected to tensile, shear, or bending forces, axial slippage will occur between the card and the plug, or the card may partially embed into the plug (or the card may deform under force), resulting in axial clearance in the mechanical joint. That is, when using this type of mechanical joint to connect precast concrete piles, when subjected to tensile, shear, or bending forces, a corresponding axial clearance will also occur between the connecting end faces of the precast concrete piles, causing cracks to form at the mechanical joint connection of the precast concrete piles. 4. Since the large nut and the middle nut, and the small nut and the plug rod are all connected by threads, the threaded connection will also have a certain axial clearance. Therefore, when the mechanical joint is subjected to tensile, shear, or bending forces, the axial clearance of the threaded connection will also cause a corresponding axial clearance between the connecting end faces of the precast concrete piles, resulting in cracks to form at the mechanical joint connection of the precast concrete piles. This mechanical structure has several shortcomings, therefore, when using this mechanical joint for connecting precast concrete piles, the connection may fail to meet the requirements of Article 5.1.7 of the "Technical Standard for Prestressed Concrete Pipe Piles" (JGJ / T406-2017), which stipulates that for prestressed pipe piles with strict requirements to be free of cracks, the crack control level should be Level 1; Article 5.1.8 stipulates that when the pipe pile is under axial tension, the crack control level should be Level 1; and when the pipe pile is under bending, the crack control level should be Level 2 for pipe piles in weakly corrosive environments and above, and Level 1 for pipe piles in moderately and strongly corrosive environments and above.

[0010] Existing mechanical joints have axial clearance issues, which cause gaps to form at the joints of precast concrete piles when subjected to tensile, shear, and / or bending forces. Since precast pile foundations are underground concealed works, the precast piles themselves cannot be repaired.

[0011] Safety hazards of cracks in precast concrete pile joints in building pile foundations:

[0012] When precast concrete piles are subjected to bending and shear forces, the axial clearance of the mechanical joints at the precast concrete pile joints will cause cracks at the connection of the precast concrete piles, which will lead to the piles not being on the same axis, resulting in local eccentric stress on the connection end face of the piles; causing damage or cracking of the concrete at the pile end face, resulting in safety hazards in the building pile foundation.

[0013] When precast concrete piles are subjected to tensile forces, it is impossible to ensure that the axial gaps generated by the aforementioned mechanical joints are completely consistent. Furthermore, the design value of the axial tensile bearing capacity of the precast pile body is based on the total number of main reinforcement bars (number of mechanical joints). As a result, the aforementioned mechanical joints will be broken one by one when subjected to tensile forces, leading to potential safety hazards in the building pile foundation.

[0014] When precast concrete piles are subjected to bending, shear, and tensile forces, axial gaps at the pile joints can lead to cracks. This can cause groundwater intrusion and corrosion of mechanical connections and / or the main reinforcement of the precast pile, making it difficult to guarantee the pile's durability. Specifically, according to Table 4.1.18 of the "Technical Specification for Building Pile Foundations" (JGJ94-2008), the annual corrosion rate of steel piles is 0.05–0.1 mm when the steel pile is above ground and in an environment without corrosive gases or corrosive volatile media. / y; When the steel pile is located below the ground and above the water level, the single-sided corrosion rate is 0.05 mm / y; when the steel pile is located below the ground and below the water level, the single-sided corrosion rate is 0.03 mm / y; when the steel pile is located below the ground and in a water level fluctuation zone, the single-sided corrosion rate is 0.1 to 0.3 mm / y. Therefore, it can be seen that when precast concrete piles develop cracks due to the axial gap of the mechanical joint, the mechanical joint and / or main reinforcement will be rapidly corroded, making it difficult to guarantee the durability of the precast pile. The severity of the damage is self-evident. Summary of the Invention

[0015] This invention addresses the problems caused by axial clearance in existing mechanical joint connection mechanisms, which leads to cracks at the connection of precast concrete piles, resulting in corrosion of the main reinforcement and / or mechanical joint, and local pressure on the pile end face. It proposes a pre-tightened mechanical joint with an intermediate sleeve to solve the safety hazards caused by the axial clearance after the connection of existing mechanical joints.

[0016] The technical means employed in this invention are as follows:

[0017] A pre-tightening mechanical connector with an intermediate sleeve includes: a plug rod, one end of which is a plug; a large nut with a receiving cavity; a locking mechanism disposed within the receiving cavity; a pre-tightening nut disposed within the receiving cavity and threadedly connected to the large nut, with a portion of the pre-tightening nut located outside the receiving cavity, and the pre-tightening nut having an insertion cavity; and an intermediate sleeve fitted over the portion of the pre-tightening nut located outside the receiving cavity, the intermediate sleeve having a transmission structure. When the plug is inserted into the insertion cavity of the pre-tightening nut and engages with the locking mechanism, the transmission structure is used to drive the intermediate sleeve to rotate from the side of the pre-tightening nut by a driving component. The rotation of the intermediate sleeve drives the pre-tightening nut to rotate and move axially along the large nut, thereby locking the plug and the locking mechanism in the axial direction of the large nut.

[0018] Furthermore, the transmission structure is an engagement or pushing structure located on the outer wall or end of the intermediate sleeve.

[0019] Furthermore, the biting or pushing structure is a biting tooth, a pushing groove, a pushing protrusion, or a conical tooth.

[0020] Furthermore, the outer wall of the intermediate sleeve is provided with a pushing groove, and the driving component is a toothed rod with driving teeth at one end. The driving teeth of the toothed rod can engage with the pushing groove from the side of the preload nut and drive the intermediate sleeve to rotate during the pushing and pulling process of the toothed rod; or, the driving component is a driving rod, one end of which can be inserted into the pushing groove from the side of the preload nut and drive the intermediate sleeve to rotate during the pushing and pulling process of the driving rod; or,

[0021] The outer wall of the intermediate sleeve is provided with a first actuating protrusion, and the driving component is an actuating rod. The actuating rod can be inserted laterally between two adjacent first actuating protrusions by the pre-tightening nut and drive the intermediate sleeve to rotate during the rotation of the actuating rod; or...

[0022] The intermediate sleeve has a first conical tooth at one end, and the driving component is a conical tooth drive rod. One end of the conical tooth drive rod has a second conical tooth. The second conical tooth of the conical tooth drive rod can engage with the first conical tooth laterally through the preload nut, driving the intermediate sleeve to rotate during the rotation of the conical tooth drive rod; or...

[0023] The end of the intermediate sleeve is provided with a second actuating protrusion, and the driving component is a bevel gear driving rod. One end of the bevel gear driving rod is provided with a second bevel tooth. The second bevel tooth of the bevel gear driving rod can engage with the second actuating protrusion from the side of the pre-tightening nut and drive the intermediate sleeve to rotate during the rotation of the bevel gear driving rod.

[0024] Furthermore, the intermediate sleeve and the preload nut are connected by a key or teeth, so that the intermediate sleeve and the preload nut can rotate synchronously and move relative to each other in the axial direction.

[0025] Furthermore, it also includes a positioning sleeve disposed in the receiving cavity for correcting the insert rod during the insertion of the insert rod into the receiving cavity.

[0026] Furthermore, the positioning sleeve is disposed between the end of the pre-tightening nut placed inside the large nut and the bottom surface of the receiving cavity. The positioning sleeve is provided with a positioning hole. After the plug is inserted into the insertion cavity of the pre-tightening nut and radially engaged with the snap-fit ​​mechanism, part of the plug is inserted into the positioning hole. The radial gap between the plug and the positioning hole is smaller than the radial gap between the snap-fit ​​mechanism and the pre-tightening nut, or the radial gap between the plug and the positioning hole is smaller than the radial gap between the snap-fit ​​mechanism and the plug.

[0027] Furthermore, the locking mechanism consists of multiple elastic clips disposed on one end of the pre-tightening nut placed inside the large nut. The pre-tightening nut rotates and moves axially along the large nut, and the locking surfaces at the ends of the multiple elastic clips can abut against the second locking surface on the plug to lock the plug and the pre-tightening nut in the axial direction of the large nut.

[0028] Furthermore, the locking mechanism consists of multiple elastic cards disposed on one end of the plug placed inside the large nut. The inner wall of the elastic card is provided with a first tooth, and the outer wall of the plug is provided with a second tooth. The first tooth and the second tooth engage with each other. When the pre-tightening nut rotates and moves along the axial direction of the large nut, the tooth surfaces of the first tooth and the second tooth can abut against each other to lock the plug and the pre-tightening nut in the axial direction of the large nut.

[0029] Furthermore, the insertion cavity of the pre-tightening nut is provided with a card receiving groove, the snap-fit ​​mechanism is a card provided in the card receiving groove, the inner wall of the card receiving groove near the plug insertion end of the pre-tightening nut is a first snap-fit ​​surface, and the plug is provided with a second snap-fit ​​surface;

[0030] When the plug is inserted into the insertion cavity of the pre-tightening nut and engages with the card, the card is located between the first engagement surface and the second engagement surface; the pre-tightening nut rotates and moves along the axial direction of the large nut, causing the first engagement surface to move toward the card and causing the first engagement surface and the second engagement surface to abut against the card respectively, so as to lock the plug and the pre-tightening nut in the axial direction of the large nut.

[0031] Furthermore, the card receiving groove is directly machined on the inner wall of the insertion cavity of the preload nut; or, a retaining ring is provided in the insertion cavity of the preload nut, and a card receiving groove is formed between the retaining ring and the snap-fit ​​surface in the insertion cavity.

[0032] Furthermore, before the plug and the locking mechanism are locked in the axial direction of the large nut, the threaded connection between the preload nut and the large nut is a loose-fit threaded connection.

[0033] Furthermore, after the plug and the locking mechanism are locked in the axial direction of the large nut, the tensile strength of the connection between the plug and the locking mechanism is greater than or equal to the tensile strength of any one of the main rib, the large nut, and the small nut.

[0034] Furthermore, it also includes a small nut for connecting to the base of the insert rod.

[0035] A precast concrete pile includes a precast concrete pile body, main reinforcement bars, and a pre-tightening mechanical joint with an intermediate sleeve as disclosed in this invention. The main reinforcement bars are disposed within the precast concrete pile body. One end of the precast concrete pile body is provided with a large nut, and the large nut contains the locking mechanism and the pre-tightening nut. The other end of the precast concrete pile body is equipped with the insertion rod. The end of the precast concrete pile body is provided with a drive component receiving groove. When two adjacent precast concrete pile sections are connected, one end of the drive component receiving groove communicates with the outer wall of the precast concrete pile body, and the other end extends to the end of the locking nut. After the drive component is inserted into the drive component receiving groove from the outer wall of the precast concrete pile body, the drive component can interact with the transmission structure disposed on the pre-tightening nut, causing the pre-tightening nut to rotate and move axially along the large nut, thereby locking the insertion rod and the locking mechanism in the axial direction of the large nut.

[0036] Furthermore, the precast concrete pile body has a small nut at one end of the insert rod, and one end of the large nut and the small nut are respectively connected to the two ends of the main reinforcement. The insert rod is threadedly connected to the other end of the small nut.

[0037] Furthermore, after the drive component drives the intermediate sleeve to rotate and locks the plug and the snap-fit ​​mechanism in the axial direction of the large nut, the drive component remains in or is removed from the drive component receiving groove.

[0038] Furthermore, structural adhesive is injected into the connecting end face of the precast concrete pile body and into the pre-tightening mechanical joint with intermediate sleeve.

[0039] A method for connecting precast concrete piles according to the present invention includes the following steps:

[0040] The end of the precast concrete pile with the insertion rod and the end of the adjacent precast concrete pile with the pre-tightening nut are moved relative to each other, and the plug is inserted into the insertion cavity of the pre-tightening nut to achieve the snap-fit ​​between the plug and the snap-fit ​​mechanism.

[0041] A drive component is inserted into the outer wall of a precast concrete pile, and the drive component drives the transmission structure, thereby causing the preload nut to rotate and move axially along the large nut, thereby locking the plug and the snap-fit ​​mechanism in the axial direction of the large nut.

[0042] Compared with the prior art, the pre-tightening mechanical connector with an intermediate sleeve disclosed in this invention has the following beneficial effects: The pre-tightening mechanical connector with an intermediate sleeve disclosed in this application, due to the presence of an intermediate sleeve with a transmission structure, can be driven by a driving component from the side of the pre-tightening nut after the plug is inserted into the cavity and radially engaged with the locking mechanism. This causes the pre-tightening nut to move axially along the large nut, thereby locking the plug and the locking mechanism in the axial direction of the large nut. This effectively eliminates the axial gap between the plug, the locking mechanism, and the pre-tightening nut. Furthermore, because the pre-tightening nut, the insertion rod, and the locking mechanism are locked in the axial direction, during the locking process, the pre-tightening nut, the insertion rod, and the locking mechanism... The rod and clamping mechanism generate a certain axial force (tightening force) in the axial direction. Under the action of this axial force, the axial gaps between components such as the pre-tightening nut, insert rod, large nut, clamping mechanism, and small nut can be effectively eliminated. Therefore, when using the mechanical joint disclosed in this invention for precast concrete pile connection, the precast concrete pile connection will not crack under tensile, shear, or bending forces. This ensures that the mechanical joint disclosed in this invention meets the relevant requirements for crack level control in the "Technical Standard for Prestressed Concrete Pipe Piles" JGJ / T406-2017. Furthermore, it eliminates the problem of gaps generated in existing mechanical joint connections, which cause cracks at the precast concrete pile joint and pose safety hazards to the building pile foundation. Attached Figure Description

[0043] Figure 1 This is a front view of a first embodiment of the pre-tightening mechanical joint with an intermediate sleeve disclosed in this invention. The transmission structure in the figure adopts a bevel gear form.

[0044] Figure 2 This is an axial view of a first embodiment of the pre-tightening mechanical joint with an intermediate sleeve disclosed in this invention;

[0045] Figure 3 This is a cross-sectional view of the first embodiment of the pre-tightening mechanical joint with an intermediate sleeve disclosed in this invention. The snap-fit ​​mechanism in the figure is in the form of an elastic card, and is a schematic diagram of the state when the plug and the pre-tightening nut are not axially locked.

[0046] Figure 4 This is a schematic diagram of the state after the plug and the snap-fit ​​mechanism are axially locked following the insertion of the plug into the pre-tightening nut, according to the first embodiment of the pre-tightening mechanical joint with intermediate sleeve disclosed in this invention.

[0047] Figure 5 This is a schematic diagram of the structure of the preload nut of the first embodiment of the preload mechanical joint with intermediate sleeve disclosed in this invention;

[0048] Figure 6a This is a schematic diagram of the drive component of the pre-tightening mechanical joint with an intermediate sleeve disclosed in this invention, showing a bevel gear drive rod.

[0049] Figure 6b This is a schematic diagram of the intermediate sleeve of the pre-tightening mechanical joint with intermediate sleeve disclosed in this invention. The intermediate sleeve in the figure has a conical tooth structure.

[0050] Figure 7 This is a structural diagram of the insertion rod in the first embodiment of the pre-tightening mechanical joint with an intermediate sleeve disclosed in this invention;

[0051] Figure 8 This is a front view of a second embodiment of the pre-tightening mechanical joint with an intermediate sleeve disclosed in this invention. The transmission structure in the figure adopts a bevel gear and a protrusion.

[0052] Figure 9 This is an axial view of a second embodiment of the pre-tightening mechanical joint with an intermediate sleeve disclosed in this invention;

[0053] Figure 10 This is a front view of a third embodiment of the transmission structure of the pre-tightening mechanical joint with an intermediate sleeve disclosed in this invention. The transmission structure in the figure adopts the form of a pushing groove and a toothed rod.

[0054] Figure 11 This is a front view of the fourth embodiment of the transmission structure of the pre-tightening mechanical joint with intermediate sleeve disclosed in this invention. The transmission structure in the figure adopts the form of a pushing groove and a driving rod.

[0055] Figure 12 This is a front view of the fifth embodiment of the transmission structure of the pre-tightening mechanical joint with intermediate sleeve disclosed in this invention. The transmission structure in the figure adopts the form of a pushing groove and a lead screw.

[0056] Figure 13 This is a front view of the sixth embodiment of the transmission structure of the pre-tightening mechanical joint with intermediate sleeve disclosed in this invention. The transmission structure in the figure adopts the form of a wave rod and a protrusion.

[0057] Figure 14 This is a top view of the positioning sleeve of the pre-tightening mechanical joint with an intermediate sleeve disclosed in this invention;

[0058] Figure 15 This is an axial view of the positioning sleeve of the pre-tightening mechanical joint with an intermediate sleeve disclosed in this invention;

[0059] Figure 16 This is a second embodiment of the snap-fit ​​mechanism for a pre-tightening mechanical joint with an intermediate sleeve disclosed in this invention. The snap-fit ​​mechanism in the figure adopts the form of a flexible card with snap-fit ​​teeth.

[0060] Figure 17 This is a partially enlarged schematic diagram of the state of the first and second teeth when the insert rod and the locking nut are not axially locked, in the second embodiment of the snap-fit ​​mechanism of the pre-tightened mechanical joint with intermediate sleeve disclosed in this invention.

[0061] Figure 18 This is a partially enlarged schematic diagram of the state of the first and second teeth when the insert rod and the locking nut are axially locked in a second embodiment of the snap-fit ​​mechanism of the pre-tightening mechanical joint with an intermediate sleeve disclosed in this invention.

[0062] Figure 19 This is a third embodiment of the snap-fit ​​mechanism for a pre-tightened mechanical joint with an intermediate sleeve disclosed in this invention. The snap-fit ​​mechanism adopts a snap ring structure, and the insert rod and the locking nut are not axially locked in the figure.

[0063] Figure 20 This is a third embodiment of the snap-fit ​​mechanism for a pre-tightened mechanical joint with an intermediate sleeve disclosed in this invention. The snap-fit ​​mechanism adopts a snap ring structure, and the insert rod and the locking nut are axially locked in the figure.

[0064] Figure 21 This is a structural diagram of the pre-tightening nut in the third embodiment of the snap-fit ​​mechanism of the pre-tightening mechanical joint with intermediate sleeve disclosed in this invention;

[0065] Figure 22 This is a front view of the retaining ring in the third embodiment of the snap-fit ​​mechanism with an intermediate sleeve of the pre-tightening mechanical joint disclosed in this invention;

[0066] Figure 23 The axial view of the retaining ring in the third embodiment of the snap-fit ​​mechanism with intermediate sleeve of the pre-tightened mechanical joint disclosed in this invention;

[0067] Figure 24 This is the fourth embodiment of the snap-fit ​​mechanism for a pre-tightened mechanical joint with an intermediate sleeve disclosed in this invention. The snap-fit ​​mechanism adopts a snap ring structure, and the snap ring receiving groove is formed by a retaining ring and a pre-tightening nut. In the figure, the insert rod and the locking nut are not axially locked.

[0068] Figure 25 This is the fourth embodiment of the snap-fit ​​mechanism of the pre-tightened mechanical joint with intermediate sleeve disclosed in this invention. In the figure, the insert rod and the locking nut are axially locked.

[0069] Figure 26This is a schematic diagram of a precast concrete pile connection with a pre-tightened mechanical joint having an intermediate sleeve as disclosed in this invention. The number of piles in the diagram is two sections.

[0070] Figure 27 This is a cross-sectional view of a precast concrete pile connection with a pre-tightened mechanical joint having an intermediate sleeve as disclosed in this invention.

[0071] Figure 28 for Figure 27 A magnified view of a section at point D;

[0072] Figure 29 An end view of a precast concrete pile connection with a pre-tightened mechanical joint having an intermediate sleeve as disclosed in this invention.

[0073] Figure 30 for Figure 29 A magnified view of a section at point F in the middle;

[0074] Figure 31 This is a structural diagram of the first type of existing mechanical connector, with the plug in an over-insertion state.

[0075] Figure 32 This is a structural diagram of the first type of existing mechanical connector, with the plug in a partially inserted state.

[0076] Figure 33 This is a structural diagram of the existing second type of mechanical connector, showing the insertion process when the axis of the insertion rod and the axis of the intermediate nut are not collinear.

[0077] Figure 34 The diagram shows the structure of the second type of mechanical connector. In the diagram, the plug of the insertion rod contacts the lower card first, preventing the lower card from entering between the plug and the middle nut.

[0078] Figure 35 This is a structural diagram of the existing second type of mechanical connector, in which multiple clips are held at different positions between the plug and the intermediate nut;

[0079] Figure 36 This is a schematic diagram showing the contact state between the card and the plug contact surface of the existing second type of mechanical connector;

[0080] In the diagram: 1. Insert rod; 10. Plug; 11. Insert rod connecting part; 12. Insert rod base; 13. Second snap-fit ​​surface; 14. Second tooth; 2. Large nut; 20. Receiving cavity; 21. Small nut; 4. Pre-tightening nut; 40. Insertion cavity; 41. Elastic card; 410. Snap-fit ​​surface at the end of the elastic card; 42. First tooth; 43. Card receiving groove; 430. First snap-fit ​​surface; 44. Retaining ring; 45. Card; 5. Intermediate sleeve; 5 0. Transmission structure; 501. Pushing groove; 503. First actuating protrusion; 504. First conical tooth; 505. Second actuating protrusion; 6. Drive component; 60. Toothed rod; 600. Drive tooth; 61. Drive rod; 62. Actuating rod; 63. Conical tooth drive rod; 630. Second conical tooth; 7. Positioning sleeve; 70. Positioning hole; 8. Precast concrete pile; 80. Precast concrete pile body; 81. Main reinforcement; 82. Drive component receiving groove. Detailed Implementation

[0081] Example 1

[0082] like Figure 1 , Figure 2 and Figure 3 The figure shown is a pre-tightening mechanical joint with an intermediate sleeve disclosed in this invention, comprising:

[0083] Insert rod 1, one end of which is a plug 10; large nut 2, which has a receiving cavity 20; snap-fit ​​mechanism, which is disposed in the receiving cavity 20; preload nut 4, which is disposed in the receiving cavity 20 and threadedly connected to the large nut 2, with part of the preload nut 4 located outside the receiving cavity 20, and the preload nut 4 has an insertion cavity 40.

[0084] An intermediate sleeve 5 is fitted onto the portion of the pre-tightening nut 4 located outside the receiving cavity 20. The intermediate sleeve 5 is provided with a transmission structure. When the plug 10 is inserted into the insertion cavity 40 of the pre-tightening nut 4 and engages with the locking mechanism, the transmission structure is driven by a driving component 6 to rotate the intermediate sleeve 5 from the side of the pre-tightening nut 4. The rotation of the intermediate sleeve 4 can drive the pre-tightening nut 4 to rotate and move along the axial direction of the large nut 2, thereby locking the plug 10 and the locking mechanism in the axial direction of the large nut 2.

[0085] The pre-tightening mechanical joint with an intermediate sleeve disclosed in this application has an intermediate sleeve 5, which is fitted onto the pre-tightening nut 4 at the outer end of the large nut. The intermediate sleeve and the pre-tightening nut can rotate synchronously and move axially relative to each other. The intermediate sleeve 5 is equipped with a transmission structure, such as... Figure 3 and Figure 4As shown, the transmission structure is capable of rotating the intermediate sleeve 4 from the side of the pre-tightening nut 4 after the plug 10 of the insertion rod 1 is inserted into the insertion cavity 40 of the pre-tightening nut 4 and radially engaged with the locking mechanism placed in the receiving cavity 20. Figure 3 The diagram illustrates the movement process. Specifically, after the plug is inserted into the locking nut, there is a certain axial gap L between the locking mechanism and the plug's locking surface. Under the action of external force, the driving component 6 causes the pre-tightening nut 4 to rotate radially (as shown by arrow B in the diagram) and move axially along the large nut 2 (as shown by arrow C in the diagram), thereby locking the plug 10 and the locking mechanism in the axial direction of the large nut 2. That is, after the plug 10 of the insertion rod 1 is locked with the locking mechanism, the pre-tightening nut 4 can move axially along the large nut 2 under the drive of the intermediate sleeve 5 and the driving component 6, thereby eliminating the axial gap L between the plug 10, the locking mechanism, and the pre-tightening nut 4 through the axial movement of the pre-tightening nut 4. Furthermore, since the pre-tightening nut, insertion rod, and locking mechanism are locked in the axial direction, a torque (tightening force) is generated between the locking nut and the large nut during the locking process. This tightening force causes the pre-tightening nut, insertion rod, and locking mechanism to generate a certain axial force in the axial direction. Under this action, the axial gaps between components such as the pre-tightening nut, insert rod, large nut, snap-fit ​​mechanism, and small nut can be effectively eliminated. For example, the gap between the threaded connection of the pre-tightening nut and the large nut (the axial gap of the threaded connection in area E2 of the figure), the gap between the threaded connection of the insert rod base and the small nut (the axial gap of the threaded connection in area E1 of the figure), and the gap between the insert rod plug and the snap-fit ​​mechanism, etc. Therefore, when using the mechanical joint disclosed in this invention to connect precast concrete piles, the connection of the precast concrete pile will not crack or generate cracks when subjected to pull-out force, shear force, or bending force. That is, when using the mechanical joint disclosed in this invention to connect precast concrete piles, the connection of the pile has high pull-out resistance, bending resistance, and shear resistance. This allows the use of the mechanical joint disclosed in this invention to meet the relevant requirements for crack level control in the "Technical Standard for Prestressed Concrete Pipe Piles" JGJ / T406-2017. This invention eliminates the problem of gaps and cracks at the joints of precast concrete piles caused by existing mechanical joints, which pose safety hazards to the pile foundation. Furthermore, by using an intermediate sleeve to drive the preload nut, the intermediate sleeve can remain in a constant axial position while the preload nut achieves a larger axial stroke. Therefore, the intermediate sleeve and driving components can be made smaller, allowing the preload nut to achieve a larger stroke.

[0086] Furthermore, the transmission structure is an engagement or pushing structure located on the outer wall or end of the intermediate sleeve 5. The engagement or pushing structure can be engagement teeth, pushing grooves, actuating protrusions, or conical teeth. Specifically, for example... Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6a and Figure 6b The first embodiment of the transmission structure of the present invention is shown. In this embodiment, the end of the intermediate sleeve 5 is provided with a first bevel tooth 504, the driving component 6 is a bevel tooth driving rod 63, and one end of the bevel tooth driving rod 63 is provided with a second bevel tooth 630. The second bevel tooth 630 of the bevel tooth driving rod 63 can engage with the first bevel tooth 504 from the side of the preload nut 4 and drive the intermediate sleeve 5 to rotate during the rotation of the bevel tooth driving rod 63. The intermediate sleeve drives the preload nut to rotate, thereby realizing the rotation of the preload nut and its axial movement along the large nut, thereby locking the plug and the snap-fit ​​mechanism in the axial direction of the large nut.

[0087] like Figure 8 and Figure 9 The following is a second embodiment of the transmission structure of the present invention. In this embodiment, the end of the intermediate sleeve 5 is provided with a second actuating protrusion 505, and the driving component 6 is a bevel drive rod 63. One end of the bevel drive rod 63 is provided with a second bevel tooth 630. The second bevel tooth 630 of the bevel drive rod 63 can engage with the second actuating protrusion 505 from the side of the preload nut 4 and drive the intermediate sleeve 5 to rotate during the rotation of the bevel drive rod 63. The intermediate sleeve drives the preload nut to rotate, thereby realizing the rotation of the preload nut and its movement along the axial direction of the large nut, thereby locking the plug and the snap-fit ​​mechanism in the axial direction of the large nut.

[0088] like Figure 10 The diagram shows a third embodiment of the transmission structure in this invention. In this embodiment, the outer wall of the intermediate sleeve 5 is provided with a pushing groove 501. The driving component 6 is a toothed rod 60, which is a long column structure. The front end of the long column is provided with multiple protrusions along the axial direction of the rod to form driving teeth 600. The driving teeth are adapted to the pushing groove. The driving teeth 600 of the toothed rod 60 can be engaged with the pushing groove 501 from the side of the pre-tightening nut 4. The reciprocating push and pull of the toothed rod 60 can make the intermediate sleeve rotate. (When pulling the toothed rod, the toothed rod can be rotated at a certain angle to separate the driving teeth from the pushing groove. After the toothed rod is pulled out, the toothed rod is rotated again to make the driving rod engage with the pushing groove and push the toothed rod.) This enables the intermediate sleeve to drive the locking nut to rotate and move along the axial direction of the large nut, thereby locking the plug and the snap-fit ​​mechanism in the axial direction of the large nut.

[0089] like Figure 11The image shows a fourth embodiment of the transmission structure in this invention. In this embodiment, the outer wall of the intermediate sleeve 5 is provided with a pushing groove 501, and the driving component 6 is a driving rod 61. The driving rod is a long column structure, and the front end of the long column can be inserted into the pushing groove from the side of the pre-tightening nut 4 along the inclined direction. The reciprocating pushing of the driving rod can make the intermediate sleeve rotate and drive the pre-tightening nut to rotate, thereby realizing the locking nut moving along the axial direction of the large nut, thereby locking the plug and the pre-tightening nut in the axial direction of the large nut.

[0090] like Figure 12 The fifth embodiment of the transmission structure of the present invention is shown. In this embodiment, the outer wall of the intermediate sleeve 5 is provided with a pushing groove 501, the driving component 6 is a toothed rod 60, one end of the toothed rod 60 is provided with continuous driving teeth 600, the driving teeth 600 of the toothed rod 60 can be engaged with the meshing teeth 502 by the side of the pre-tightening nut 4 and drive the intermediate sleeve 5 to rotate during the rotation of the toothed rod 60.

[0091] like Figure 13 The image shows a sixth embodiment of the transmission structure in this invention. In this embodiment, the outer wall of the intermediate sleeve 5 is provided with a first actuating protrusion 503, and the driving component 6 is an actuating rod 62. The actuating rod 62 can be inserted laterally between two adjacent first actuating protrusions 503 by the pre-tightening nut 4 and drives the intermediate sleeve 5 to rotate during the rotation of the actuating rod 62. Specifically, a plurality of protrusions are uniformly provided circumferentially on the outer wall of the intermediate sleeve to form actuating protrusions. The driving component is the actuating rod 62, which is a long rod structure. The front end of the long rod is a flat structure and can be inserted into two adjacent actuating protrusions. As shown in the figure, the lever can rotate under the drive of an external tool. During the rotation of the lever, one side of the front end of the lever contacts the corresponding protrusion and drives the locking nut to rotate. When the lever rotates one revolution, the front end of the lever contacts another adjacent protrusion and continues to drive the intermediate sleeve to rotate. That is, the rotation of the lever can cause the intermediate sleeve to rotate, thereby driving the locking nut to rotate and move along the axial direction of the large nut, thus locking the plug and the pre-tightening nut (clamping mechanism) in the axial direction of the large nut. The lever can be made using a structure such as a flathead screwdriver. The transmission structure of this application is not limited to the specific structures described above. Any structure that can achieve the function of driving the intermediate sleeve to rotate from the side is within the protection scope of this patent. This application will not describe each specific structure that can achieve this function.

[0092] Furthermore, in this embodiment, to ensure that the intermediate sleeve can both drive the preload nut to rotate and allow the preload nut to move axially along the large nut (the preload nut and the intermediate sleeve move relative to each other axially), such as... Figure 10As shown, the intermediate sleeve 5 and the preload nut 4 can be connected by various methods such as keys or teeth. When a key connection is used, keyways can be machined on both the intermediate sleeve and the preload nut, and a key can be used to connect them. Alternatively, keys (keyways) and keyways (keys) can be machined on both the intermediate sleeve and the preload nut to achieve a key connection. When the intermediate sleeve and the preload nut are connected by teeth, the preload nut has a toothed structure machined on the outer wall of one end of the large nut, and a toothed structure is also machined on the inner diameter of the intermediate sleeve. The intermediate sleeve can fit onto the preload nut, and the teeth interlock. Furthermore, by using an intermediate sleeve to drive the preload nut to rotate, the preload nut can have a large axial travel, ensuring axial locking between the insert and the preload nut.

[0093] Furthermore, it also includes a positioning sleeve 7 disposed in the receiving cavity 20 for correcting the insertion rod 1 during the insertion of the insertion rod 1 into the receiving cavity 20. By providing a positioning sleeve 7 in the receiving cavity 20 for correcting the insertion rod 1 during the insertion of the insertion rod 1 into the receiving cavity 20, it can be ensured that the axis of the insertion rod 1 is substantially coincident with or substantially parallel to the axis of the large nut 2, thereby reducing or eliminating the contact between the insertion rod 1 and the pre-tightening nut 4 in the radial direction during and / or after the insertion of the insertion rod 1 into the pre-tightening nut 4, that is, reducing the force between the insertion rod 1 and the pre-tightening nut 4, so that the intermediate sleeve can drive the pre-tightening nut 4 to rotate, so that the pre-tightening nut 4 moves axially along the large nut 2, thereby locking the plug 10 and the locking mechanism in the axial direction of the large nut 2.

[0094] Furthermore, such as Figure 14 and Figure 15 As shown, the positioning sleeve 7 is disposed between the end of the pre-tightening nut 4 placed inside the large nut and the bottom surface of the receiving cavity 20. The positioning sleeve 7 is provided with a positioning hole 70. After the plug 10 is inserted into the insertion cavity 40 of the pre-tightening nut 4 and radially engaged with the snap-fit ​​mechanism, part of the plug 10 is inserted into the positioning hole 70, and the radial gap between the plug 10 and the positioning hole 70 is smaller than the radial gap between the snap-fit ​​mechanism and the pre-tightening nut 4, or the radial gap between the plug 10 and the positioning hole 70 is smaller than the radial gap between the snap-fit ​​mechanism and the plug 10. Specifically, in this embodiment, as... Figure 14 and Figure 15As shown, the positioning sleeve 7 has a circular ring structure, preferably a circular metal sheet. The outer diameter of the positioning sleeve 7 has a threaded structure. The positioning sleeve 7 can be threaded into the receiving cavity containing the large nut 2. The large nut has a receiving cavity 20, and the inner wall of the receiving cavity 20 has an internal thread. One end of the large nut can be fixedly connected to the main rib, and the other end is connected to the locking nut through the internal thread. Preferably, the positioning sleeve 7 can be screwed into the root of the internal thread of the large nut. The inner diameter hole of the positioning sleeve 7 is a positioning hole 70. During the process of inserting the plug 10 into the insertion cavity 40 of the pre-tightening nut 4 or after radial engagement with the locking mechanism, part of the plug 10 is inserted into the positioning hole 70. Preferably, the diameter of the positioning hole is adapted to the outer diameter of the plug, so that the radial gap between the plug 10 and the positioning hole 70 is less than 1 / 2 mm. The radial gap between the snap-fit ​​mechanism and the pre-tightening nut 4, or the radial gap between the plug 10 and the positioning hole 70, is smaller than the radial gap between the snap-fit ​​mechanism and the plug 10. Since the radial gap between the plug 10 and the positioning hole 70 is smaller than the radial gap between the snap-fit ​​mechanism and the pre-tightening nut or between the snap-fit ​​mechanism and the plug, the positioning hole 70 limits and guides the plug 1 during the insertion of the pre-tightening nut 4 and / or after the plug 1 is inserted into the pre-tightening nut 4. This results in a gap (no contact) between the plug 1 and the pre-tightening nut 4 in the radial direction, which reduces or eliminates the force between the plug and other components and the pre-tightening nut. This allows the intermediate sleeve to drive the pre-tightening nut to rotate, causing the pre-tightening nut to move along the axial direction of the large nut, thereby locking the plug and the pre-tightening nut in the axial direction of the large nut. Preferably, the positioning hole 70 of the positioning sleeve 7 is a polygonal hole, the diameter of the inscribed circle of the polygon is greater than or equal to the maximum outer diameter of the plug 10 and less than the inner diameter of the insertion cavity 40 of the preload nut 4, and is an octagonal hole in the figure; the positioning hole is a polygonal hole, which makes it easy to insert tools such as an Allen wrench into the positioning hole to screw the positioning sleeve into the large nut.

[0095] The receiving cavity 20 of the large nut 2 can also be a stepped hole. The diameter of the stepped hole near the bottom surface of the receiving cavity is smaller, and the diameter of the stepped hole near the opening end is larger. An internal thread for threaded connection with the preload nut 4 is machined on the inner wall of the receiving cavity 20 of the large nut 2 (at the stepped hole with the larger diameter near the opening end). A positioning sleeve mounting hole is provided at the root of the internal thread (i.e., the end of the internal thread facing the bottom surface of the receiving cavity). The diameter of the positioning sleeve mounting hole is larger than the diameter of the hole near the bottom surface of the receiving cavity and smaller than the diameter of the stepped hole near the opening end. The positioning sleeve 7 is a ring-shaped structure, preferably a ring-shaped metal sheet. The outer diameter of the positioning sleeve 7 is interference-fitted with the positioning sleeve mounting hole. The positioning sleeve 7 is inserted into the positioning sleeve mounting hole under external force. The inner diameter hole of the positioning sleeve 7 is a positioning hole 70, and the inner diameter of the positioning hole 70 is greater than or equal to the insertion hole. The maximum outer diameter of the head 10 is smaller than the inner diameter of the insertion cavity 40 of the pre-tightening nut 4. After the plug 10 of the insert rod 1 passes through the insertion cavity 40 of the pre-tightening nut 4, the plug 10 is inserted into the positioning hole 70. Since the radial gap between the plug 10 and the positioning hole 70 is smaller than the radial gap between the snap-fit ​​mechanism and the pre-tightening nut or between the snap-fit ​​mechanism and the plug, the positioning hole 70 limits and guides the insert rod 1 during the insertion of the pre-tightening nut 4 and / or after the insert rod 1 is inserted into the pre-tightening nut 4. This results in a gap (no contact) between the insert rod 1 and the pre-tightening nut 4 in the radial direction, which reduces or eliminates the force between the insert rod and other components and the pre-tightening nut. This allows the intermediate sleeve to drive the pre-tightening nut to rotate, causing the pre-tightening nut to move axially along the large nut, thereby locking the plug and the snap-fit ​​mechanism in the axial direction of the large nut.

[0096] like Figure 3 , Figure 4 and Figure 5The first embodiment of the snap-fit ​​mechanism of the present invention is shown. In this embodiment, the snap-fit ​​mechanism consists of multiple elastic clips 41 disposed on one end of the pre-tightening nut 4 inside the large nut 2. The elastic clips and the pre-tightening nut are integrally formed, that is, multiple grooves are machined in the circumferential direction at one end of the pre-tightening nut, and an elastic clip is formed between two adjacent grooves. The ends of the elastic clips contract towards the center in the radial direction. The elastic clips can open or close outward. The ends of the elastic clips form snap-fit ​​surfaces 410. The plug 10 of the insertion rod 1 is provided with a second snap-fit ​​surface 13. The intermediate sleeve 4 drives the pre-tightening nut 4 to rotate and move along the large nut. 2. Axial movement: The engaging surfaces 410 at the ends of the multiple elastic clips can abut against the second engaging surface 13 on the plug 10 (the plug rod includes a plug rod base, a plug rod connecting part, and a plug; the diameter of the plug rod connecting part is smaller than the diameter of the plug; the transition surface between the plug rod connecting part and the plug is the second engaging surface) to achieve locking of the plug 10 and the pre-tightening nut 4 in the axial direction of the large nut 2. This effectively eliminates the axial gap between the first engaging surface and the second engaging surface after the plug is inserted into the pre-tightening nut, as well as the axial gap that exists in the threaded connection between the pre-tightening nut and the large nut, and the threaded connection between the plug rod and the small nut. Using elastic clips for engagement has advantages such as simple structure, few parts, and ease of processing and installation. In this embodiment, as... Figure 3 As shown, the large nut 2 is provided with a positioning sleeve 7. The radial gap between the positioning hole 70 of the positioning sleeve 7 and the plug is smaller than the radial gap between the elastic card (in the free state) and the connecting part of the plug rod. This allows the positioning hole 70 to limit and guide the plug rod 1 during the insertion of the pre-tightening nut 4 and / or after the plug rod 1 is inserted into the pre-tightening nut 4. This results in a gap (no contact) between the plug rod 1 and the pre-tightening nut 4 in the radial direction, which reduces or eliminates the force between the plug rod and other components and the pre-tightening nut. This allows the intermediate sleeve to drive the pre-tightening nut to rotate, causing the pre-tightening nut to move along the axial direction of the large nut, thereby locking the plug and the snap-fit ​​mechanism in the axial direction of the large nut.

[0097] like Figure 16 , Figure 17 and Figure 18The diagram shows a second embodiment of the locking mechanism in this invention. In this embodiment, the locking mechanism consists of a plurality of elastic cards 41 disposed on one end of the large nut 2. The elastic cards are formed in the same way as those in Embodiment 1. In this embodiment, the inner wall of the elastic card 41 is provided with a first tooth 42, and the outer wall of the plug 10 is provided with a second tooth 14. The first tooth 42 and the second tooth 14 engage with each other. When the pre-tightening nut 4 rotates and moves axially along the large nut 2, the tooth surfaces of the first tooth 42 and the second tooth 14 can abut against each other to lock the plug 10 and the pre-tightening nut 4 in the axial direction of the large nut 2. In this embodiment, a locking tooth structure is simultaneously provided to engage the insert rod with the preload nut, which reduces the axial clearance before the insert rod and preload nut are axially locked. In this embodiment, before the insert rod and preload nut are axially locked, the axial clearance between the insert rod and preload nut is less than or equal to 0.5 times the tooth pitch, which is much smaller than the axial clearance present in embodiment 1. Therefore, when the intermediate sleeve drives the preload nut to rotate, the preload nut only needs to move a small axial distance to achieve the tooth surfaces of the first and second teeth abutting each other, thereby achieving rapid axial locking between the preload nut and the insert rod. Furthermore, in this embodiment, the insert rod and preload nut have a large axial contact length after axial locking, improving bending and shear resistance. In this embodiment, as... Figure 18 As shown, a positioning sleeve is also provided inside the large nut. The radial gap between the positioning hole of the positioning sleeve and the plug is smaller than the radial gap between the tooth tip of the first tooth and the tooth root of the second tooth. This allows the positioning hole 70 to limit and guide the insertion rod 1 during the insertion of the insertion rod 1 into the pre-tightening nut 4 and / or after the insertion rod 1 is inserted into the pre-tightening nut 4. This results in a gap (no contact) between the insertion rod 1 and the pre-tightening nut 4 in the radial direction, which reduces or eliminates the force between the insertion rod and other components and the pre-tightening nut. This allows the intermediate sleeve to drive the pre-tightening nut to rotate, causing the pre-tightening nut to move axially along the large nut, thereby locking the plug and the snap-fit ​​mechanism in the axial direction of the large nut.

[0098] like Figure 19 , Figure 20 and Figure 21 The image shows a third embodiment of the snap-fit ​​mechanism of the present invention. In this embodiment, the insertion cavity 40 of the pre-tightening nut 4 is provided with a card receiving groove 43, and the snap-fit ​​mechanism is a card 45 disposed in the card receiving groove 43. The snap-fit ​​ring 45 is as follows: Figure 22 and Figure 23The diagram shows a metal elastic ring structure with an opening on one side. Other structures are also possible, such as multiple snap rings secured by spring clamps. The card can open or retract within the card receiving groove. The inner wall of the card receiving groove 43 near the plug insertion end 45 of the pre-tightening nut 4 forms a first engaging surface 430. The plug 10 has a second engaging surface 13. When the plug is inserted into the pre-tightening nut, the card can open radially and engage with the plug rod at the connecting part. When the plug 10 is inserted into the insertion cavity 40 of the pre-tightening nut 4 and engages with the card 3, the card 3 is located between the first engaging surface 430 and the second engaging surface 13. The preload nut 4 is rotated and moves axially along the large nut 2, causing the first snap-fit ​​surface 430 to move towards the card 45 and the first snap-fit ​​surface 430 and the second snap-fit ​​surface 13 to abut against the two sides of the card 45 respectively, thereby locking the plug 10 and the preload nut 4 in the axial direction of the large nut 2. In this embodiment, since a card receiving groove is provided on the inner wall of the insertion cavity of the preload nut, and the snap-fit ​​mechanism uses a card, the card can be directly installed in the card receiving groove of the preload nut, so that the two parts form an assembly, which facilitates the subsequent installation of the mechanical connector, reduces the installation difficulty, and saves costs. At the same time, the simple structure of the card and the preload nut further reduces costs. The end of the plug is hemispherical, parabolic, or frustum-shaped to facilitate radial expansion of the card. In this embodiment, as shown... Figure 19 As shown, a positioning sleeve is also provided inside the large nut. The radial gap between the positioning hole of the positioning sleeve and the plug is smaller than the radial gap between the plug and the insertion cavity of the pre-tightening nut. That is, the positioning hole is smaller than the diameter of the insertion cavity. This allows the positioning hole 70 to limit and guide the insertion rod 1 during the insertion of the insertion rod 1 into the pre-tightening nut 4 and / or after the insertion rod 1 is inserted into the pre-tightening nut 4. This results in a gap (no contact) between the insertion rod 1 and the pre-tightening nut 4 in the radial direction, which reduces or eliminates the force between the insertion rod and other components and the pre-tightening nut. This allows the intermediate sleeve to drive the pre-tightening nut to rotate, causing the pre-tightening nut to move axially along the large nut, thereby locking the plug and the snap-fit ​​mechanism in the axial direction of the large nut. Preferably, the sidewall of the card receiving groove 42 is inclined toward the plug insertion end 43 of the pre-tightening nut 4, that is, the inner wall of the card receiving groove 42 is roughly truncated cone-shaped. When the plug is inserted into the card, the plug abuts against the inner hole of the card and exerts a downward thrust on the card (towards the bottom of the receiving cavity). The inner wall 49 of the card receiving groove will give the card a radial outward component force, making the card easier to expand. After the plug is inserted, the first snap-fit ​​surface of the pre-tightening nut gives the card a radial inward component force, making the card and the plug fit tightly, forming a self-locking structure and enhancing the resistance to pull-out.

[0099] like Figure 24 and Figure 25The diagram shows a fourth embodiment of the snap-fit ​​mechanism of the present invention. This embodiment differs from the third embodiment in that, in the third embodiment, the card receiving groove is directly machined into the inner wall of the insertion cavity 40 of the pre-tightening nut 4; in this embodiment, the insertion cavity of the pre-tightening nut is a stepped hole, and the transition surface of the stepped hole is the snap-fit ​​surface. Preferably, the snap-fit ​​surface is a conical surface. A retaining ring 44 is provided at one end of the pre-tightening nut, and the card receiving groove 43 is formed between the retaining ring 44 and the snap-fit ​​surface inside the insertion cavity 40. The split structure facilitates manufacturing.

[0100] Furthermore, before the plug 10 and the snap-fit ​​mechanism are locked in the axial direction of the large nut 2, the threaded connection between the preload nut 4 and the large nut 2 is a loose-fit threaded connection. Specifically, the tolerance of the internal thread on the inner wall of the large nut's receiving cavity and the external thread on the outer wall of the preload nut can be reasonably selected as needed, so that the threaded connection between the preload nut and the large nut is a loose-fit threaded connection. Since the preload nut and the large nut are loose-fit threaded connections, the force between the preload nut and the large nut is relatively small before the plug and the snap-fit ​​mechanism are locked, which facilitates the intermediate sleeve to drive the preload nut to rotate, so that the preload nut moves along the axial direction of the large nut, thereby locking the plug and the snap-fit ​​mechanism in the axial direction of the large nut.

[0101] Furthermore, after the plug 10 and the locking mechanism are locked in the axial direction of the large nut 2, the tensile strength of the connection between the plug 10 and the locking mechanism is greater than or equal to the tensile strength of any one of the main rib, the large nut, and the small nut. Preferably, after the plug 10 and the locking mechanism are locked in the axial direction of the large nut 2, the plug and the locking mechanism do not exhibit ductile deformation when subjected to a pull-out force of 11.7 MPa.

[0102] In this application, after the plug 10 and the locking mechanism are locked in the axial direction of the large nut 2, the tensile strength of the connection between the plug and the locking mechanism is greater than or equal to the tensile strength of any one of the main reinforcement, the large nut, and the small nut. Furthermore, after the plug and the locking mechanism are connected, there is no ductile deformation when subjected to a pull-out force of 11.7 MPa. This ensures that before the precast concrete pile with the pre-tightening mechanical joint with the intermediate sleeve disclosed in this invention is subjected to a pull-out force that causes ductile deformation of the main reinforcement, the large nut, small nut, insert rod, locking mechanism, and locking nut will not undergo ductile deformation. Therefore, no cracks or gaps will occur between the connection end faces of the two precast piles. Before the main reinforcement becomes ductile and is pulled apart, the pre-tightening mechanical joint with the intermediate sleeve disclosed in this invention can reliably connect without being damaged, further guaranteeing the connection performance of precast concrete piles connected using the pre-tightening mechanical joint with the intermediate sleeve disclosed in this invention. Specifically, the National Building Standard Design Atlas "Precast Concrete Square Piles" (Atlas No.: 20G361) details the relationship between the pile type and the prestressed main reinforcement in its table of reinforcement and mechanical properties for prestressed concrete square piles. For example, it specifies that the main prestressed reinforcement for a pile with a cross-section of 600x600 is 24Φ D 12.6; The table details the pile section type and the design value of the axial tensile bearing capacity (NtkN) of the prestressed concrete square pile in terms of axial compressive strength and flexural bearing capacity of the pile body. The table specifies that for a B-shaped pile with a pile section of 600x600, the design value of the axial tensile bearing capacity is 2544kN. From the above data, the design value of the tensile bearing capacity of the prestressed main reinforcement of the precast pile can be calculated as 2544 / 24=10.6kN; 10.6x1.1=11.66≈11.7kN. That is, the pre-tightening mechanical joint with intermediate sleeve disclosed in this application has no ductile deformation of the precast concrete pile main reinforcement and the pre-tightening mechanical joint with intermediate sleeve when the pull-out force is within 11.7kN, and there is no slippage between the components of the mechanical joint. Therefore, no gap will be generated between the connection end faces of the precast concrete pile, thus ensuring the connection performance of the precast concrete pile.

[0103] Furthermore, it also includes a small nut 21 for connecting to the insertion rod base 12 of the insertion rod 1. Specifically, in this embodiment, the insertion rod 1 is fixed to one end of the precast concrete pile by the small nut 21, and the large nut 2 is fixed to the other end of the precast concrete pile. The large nut 2 and the small nut 21 are respectively fixedly connected to both ends of the main reinforcement in the precast concrete pile. The large nut is provided with a positioning sleeve and a pre-tightening nut, etc., and two adjacent sections of precast concrete piles can be quickly connected by the pre-tightening mechanical joint with an intermediate sleeve disclosed in this application.

[0104] Example 2

[0105] like Figure 26 , Figure 27 , Figure 28 , Figure 29 and Figure 30 The image shows a precast concrete pile disclosed in this invention, comprising a precast concrete pile body 80, a main reinforcement bar 81, and a pre-tightening mechanical joint with an intermediate sleeve disclosed in this invention; the main reinforcement bar 81 is disposed inside the precast concrete pile body 80, and a large nut 2 is provided at one end of the precast concrete pile body 80, and the large nut 2 is provided with the snap-fit ​​mechanism and the pre-tightening nut 4.

[0106] The insertion rod 1 is installed at the other end of the precast concrete pile body 80; the end of the precast concrete pile body 80 is provided with a drive component receiving groove 82; when two adjacent precast concrete pile sections are connected, one end of the drive component receiving groove 82 communicates with the outer wall of the precast concrete pile body 80, and the other end extends to the end of the locking nut 4, so that after the drive component 6 is inserted into the drive component receiving groove 82 from the outer wall of the precast concrete pile body 80, the drive component 6 can interact with the transmission structure 5 provided on the pre-tightening nut 4, so that the pre-tightening nut 4 rotates and moves along the axial direction of the large nut 2, thereby locking the plug 10 and the snap-fit ​​mechanism in the axial direction of the large nut 2.

[0107] The pre-tightening mechanical connector with an intermediate sleeve disclosed in this application, due to the intermediate sleeve and the transmission structure on the intermediate sleeve, can, after the plug of the insert rod is inserted into the insertion cavity of the intermediate pre-tightening nut and radially engaged with the locking mechanism placed in the receiving cavity, be driven by a drive component from the side of the pre-tightening nut. This causes the intermediate sleeve to drive the pre-tightening nut to rotate and move axially along the large nut, thereby locking the plug and the pre-tightening nut in the axial direction of the large nut. In other words, after the plug of the insert rod is engaged with the locking mechanism, the pre-tightening nut can move axially along the large nut under the drive of the transmission structure and the drive component. This axial movement of the pre-tightening nut eliminates the axial gap between the plug of the insert rod, the locking mechanism, and the pre-tightening nut. Furthermore, since the pre-tightening nut, the insert rod, and the locking mechanism are locked in the axial direction, during the locking process, the pre-tightening nut, the insert rod, and the locking mechanism will generate a certain axial force in the axial direction. Under the action of this axial force, the axial gaps between components such as the preload nut, insert rod, large nut, snap-fit ​​mechanism, and small nut can be effectively eliminated. For example, the gap between the threaded connection of the preload nut and the large nut, the gap between the threaded connection of the insert rod base and the small nut, and the gap between the insert rod plug and the snap-fit ​​mechanism. Therefore, when using the mechanical joint disclosed in this invention for precast concrete pile connection, the precast concrete pile connection will not crack under tensile, shear, or bending forces. In other words, using the mechanical joint disclosed in this invention for precast concrete pile connection can ensure that the pile connection has high tensile, bending, and shear resistance, thus meeting the relevant requirements for crack level control in the "Technical Standard for Prestressed Concrete Pipe Piles" JGJ / T406-2017. Furthermore, it eliminates the problem of gaps generated in existing mechanical joint connection mechanisms, which can cause cracks at the precast concrete pile joint and lead to safety hazards in the building pile foundation.

[0108] Furthermore, the precast concrete pile body 80 has a small nut 21 at one end of the insert rod 1. One end of the large nut 2 and the small nut 21 are respectively connected to both ends of the main reinforcement 81, and the insert rod 1 is threadedly connected to the other end of the small nut 21. That is, the mechanical joint is set at both ends of the main reinforcement, so that the main reinforcement and the mechanical joint are coaxial, which means that the main reinforcement and the mechanical joint are on the same axis when under force, thus improving the pull-out resistance of the pile. The drive component receiving groove 82 can also be set at the end of the precast concrete pile with the small nut. When the drive component receiving groove 82 is set at the end of the precast concrete pile with the small nut, the end of the precast concrete pile with the small nut has a locking nut receiving hole, so that when the upper and lower precast piles are connected, the upper part of the locking nut is placed in the hole. One end of the drive component receiving groove 82 is connected to the precast concrete pile, and the other end is connected to the drive component receiving groove 82, so that the drive component can drive the locking nut to rotate.

[0109] Furthermore, after the driving component 6 drives the intermediate sleeve to rotate and locks the plug 10 and the snap-fit ​​mechanism in the axial direction of the large nut 2, the driving component 6 remains in or is removed from the driving component receiving groove 82. Specifically, in the connection of precast concrete piles, multiple pre-tightening nuts on the precast concrete piles can be driven radially by one driving component to achieve axial locking of all mechanical joints, eliminate axial gaps, improve the pull-out resistance of the pile, and the driving component can be reused, saving usage costs. Alternatively, in the connection of precast concrete piles, each mechanical joint can be driven by one driving component. After the driving component drives the pre-tightening nut to rotate and achieves axial locking, the driving component remains in the driving component receiving groove, that is, the driving component is not removed from the driving component receiving groove. Since multiple driving component structures are provided between the two sections of precast concrete piles, the compressive strength of the precast pile ends is further improved.

[0110] Furthermore, structural adhesive is injected into the connecting end face of the precast concrete pile body 80 and the pre-tightened mechanical joint with the intermediate sleeve. The structural adhesive can fill, bond, and seal the connecting end face, mechanical joint, and various grooves on the end face, further improving the connection performance and corrosion resistance between piles.

[0111] Example 3

[0112] A connection method for precast concrete piles according to the present invention includes the following steps: moving one end of the precast concrete pile with a plug rod and the end of the adjacent precast concrete pile with a pre-tightening nut relative to each other, and inserting the plug rod into the insertion cavity of the pre-tightening nut to achieve the snap-fit ​​between the plug rod and the snap-fit ​​mechanism.

[0113] A drive component is inserted into the outer wall of a precast concrete pile, and the drive component drives the transmission structure, thereby causing the preload nut to rotate and move axially along the large nut, thereby locking the plug and the snap-fit ​​mechanism in the axial direction of the large nut.

[0114] Using the mechanical joint disclosed in this invention for precast concrete pile connections enables the pile joints to exhibit high tensile, bending, and shear resistance. This ensures that the mechanical joints used for precast concrete pile connections meet the relevant requirements for crack level control in the "Technical Standard for Prestressed Concrete Pipe Piles" JGJ / T406-2017. Furthermore, it eliminates the problem of gaps generated in existing mechanical joint connections, which can lead to cracks at the precast concrete pile joints and pose safety hazards to the building pile foundation.

[0115] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A pre-tightening mechanical joint with an intermediate sleeve for end connection between precast concrete piles, characterized in that: include, Insert rod (1), one end of which is a plug (10); Large nut (2), the large nut (2) is provided with a receiving cavity (20); A snap-fit ​​mechanism is disposed within the receiving cavity (20); Preload nut (4), the preload nut (4) is located in the receiving cavity (20) and threadedly connected to the large nut (2), and part of the preload nut (4) is located outside the receiving cavity (20), and the preload nut (4) is provided with an insertion cavity (40). An intermediate sleeve (5) is fitted onto the portion of the pre-tightening nut (4) located outside the receiving cavity (20). The intermediate sleeve (5) is provided with a transmission structure. The transmission structure is used to drive the intermediate sleeve (5) to rotate from the side of the pre-tightening nut (4) when the plug (10) is inserted into the insertion cavity (40) of the pre-tightening nut (4) and engaged with the locking mechanism. The rotation of the intermediate sleeve (5) can drive the pre-tightening nut (4) to rotate and move along the axial direction of the large nut (2), thereby eliminating the gap between the plug (10) and the locking mechanism in the axial direction of the large nut (2) and locking the plug (10) and the locking mechanism in the axial direction of the large nut (2).

2. The pre-tightening mechanical joint with an intermediate sleeve according to claim 1, characterized in that: The transmission structure is an engagement or pushing structure located on the outer wall or end of the intermediate sleeve (5).

3. The pre-tightening mechanical joint with an intermediate sleeve according to claim 2, characterized in that: The biting or pushing structure is biting teeth, pushing grooves, actuating protrusions, or conical teeth.

4. The pre-tightening mechanical joint with an intermediate sleeve according to claim 3, characterized in that: The outer wall of the intermediate sleeve (5) is provided with a pushing groove (501), and the driving component (6) is a toothed rod (60). One end of the toothed rod (60) is provided with a driving tooth (600). The driving tooth (600) of the toothed rod (60) can be engaged with the pushing groove (501) from the side of the preload nut (4) and drive the intermediate sleeve (5) to rotate during the pushing and pulling of the toothed rod (60); or, the driving component (6) is a driving rod (61). One end of the driving rod (61) can be inserted into the pushing groove (501) from the side of the preload nut (4) and drive the intermediate sleeve (5) to rotate during the pushing and pulling of the driving rod (61); or, The outer wall of the intermediate sleeve (5) is provided with a first actuating protrusion (503), and the driving component (6) is an actuating rod (62). The actuating rod (62) can be inserted laterally between two adjacent first actuating protrusions (503) by the preload nut (4) and drive the intermediate sleeve (5) to rotate during the rotation of the actuating rod (62); or, The intermediate sleeve (5) is provided with a first bevel tooth (504) at its end. The driving component (6) is a bevel tooth driving rod (63). One end of the bevel tooth driving rod (63) is provided with a second bevel tooth (630). The second bevel tooth (630) of the bevel tooth driving rod (63) can engage with the first bevel tooth (504) from the side of the preload nut (4) and drive the intermediate sleeve (5) to rotate during the rotation of the bevel tooth driving rod (63); or, The end of the intermediate sleeve (5) is provided with a second actuating protrusion (505). The driving component (6) is a bevel drive rod (63). One end of the bevel drive rod (63) is provided with a second bevel tooth (630). The second bevel tooth (630) of the bevel drive rod (63) can be engaged with the second actuating protrusion (505) by the side of the preload nut (4) and drive the intermediate sleeve (5) to rotate during the rotation of the bevel drive rod (63).

5. The pre-tightening mechanical joint with an intermediate sleeve according to claim 1, characterized in that: The intermediate sleeve (5) and the preload nut (4) are connected by a key or teeth, so that the intermediate sleeve (5) and the preload nut (4) can rotate synchronously and move relative to each other in the axial direction.

6. The pre-tightening mechanical joint with an intermediate sleeve according to claim 1, characterized in that: It also includes a positioning sleeve (7) disposed in the receiving cavity (20) for correcting the insert (1) during the insertion of the insert (1) into the receiving cavity (20).

7. The pre-tightening mechanical joint with an intermediate sleeve according to claim 6, characterized in that: The positioning sleeve (7) is disposed between the end of the pre-tightening nut (4) placed inside the large nut and the bottom surface of the receiving cavity (20). The positioning sleeve (7) is provided with a positioning hole (70). After the plug (10) is inserted into the insertion cavity (40) of the pre-tightening nut (4) and radially engaged with the snap-fit ​​mechanism, part of the plug (10) is inserted into the positioning hole (70). The radial gap between the plug (10) and the positioning hole (70) is smaller than the radial gap between the snap-fit ​​mechanism and the pre-tightening nut (4) or the radial gap between the plug (10) and the positioning hole (70) is smaller than the radial gap between the snap-fit ​​mechanism and the plug (10).

8. The pre-tightening mechanical joint with an intermediate sleeve according to any one of claims 1 to 7, characterized in that: The locking mechanism consists of multiple elastic clips (41) disposed on one end of the pre-tightening nut (4) inside the large nut (2). The pre-tightening nut (4) rotates and moves axially along the large nut (2). The locking surfaces (410) at the ends of the multiple elastic clips can abut against the second locking surface (13) on the plug (10) to lock the plug (10) and the pre-tightening nut (4) in the axial direction of the large nut (2).

9. The pre-tightening mechanical joint with an intermediate sleeve according to any one of claims 1 to 7, characterized in that: The locking mechanism consists of multiple elastic cards (41) disposed on one end of the large nut (2). The inner wall of the elastic card (41) is provided with a first tooth (42), and the outer wall of the plug (10) is provided with a second tooth (14). The first tooth (42) and the second tooth (14) engage with each other. When the pre-tightening nut (4) rotates and moves along the axial direction of the large nut (2), the tooth surfaces of the first tooth (42) and the second tooth (14) can abut against each other to lock the plug (10) and the pre-tightening nut (4) in the axial direction of the large nut (2).

10. The pre-tightened mechanical joint with an intermediate sleeve according to any one of claims 1 to 7, characterized in that: The insertion cavity (40) of the pre-tightening nut (4) is provided with a card receiving groove (43), and the snap-fit ​​mechanism is a card (45) provided in the card receiving groove (43). The inner wall of the card receiving groove (43) near the plug insertion end of the pre-tightening nut (4) is a first snap-fit ​​surface (430), and the plug (10) is provided with a second snap-fit ​​surface (13). When the plug (10) is inserted into the insertion cavity (40) of the pre-tightening nut (4) and engages with the card (45), the card (45) is located between the first engaging surface (430) and the second engaging surface (13); the pre-tightening nut (4) rotates and moves axially along the large nut (2), causing the first engaging surface (430) to move toward the card (45) and causing the first engaging surface (430) and the second engaging surface (13) to abut against the card (45) respectively, so as to lock the plug (10) and the pre-tightening nut (4) in the axial direction of the large nut (2).

11. The pre-tightened mechanical joint with an intermediate sleeve according to claim 10, characterized in that: The card receiving groove (43) is directly machined into the inner wall of the insertion cavity (40) of the preload nut (4); or, The insertion cavity (40) of the pre-tightening nut (4) is provided with a retaining ring (44), and the retaining ring (44) and the snap-fit ​​surface in the insertion cavity (40) form the card receiving groove (43).

12. The pre-tightening mechanical joint with an intermediate sleeve according to claim 1, characterized in that: Before the plug (10) and the snap-fit ​​mechanism are locked in the axial direction of the large nut (2), the threaded connection between the pre-tightening nut (4) and the large nut (2) is a loose-fit threaded connection.

13. The pre-tightening mechanical joint with an intermediate sleeve according to claim 1, characterized in that: After the plug (10) and the snap-fit ​​mechanism are locked in the axial direction of the large nut (2), the tensile strength of the connection between the plug (10) and the snap-fit ​​mechanism is greater than or equal to the tensile strength of any one of the main rib, the large nut and the small nut.

14. The pre-tightening mechanical joint with an intermediate sleeve according to claim 1, characterized in that: It also includes a small nut (21) for connecting to the insert base (12) of the insert (1).

15. A precast concrete pile, characterized in that: Includes a precast concrete pile body (80), main reinforcement (81), and a pre-tightened mechanical joint with an intermediate sleeve as described in any one of claims 1 to 14; The main reinforcement (81) is set inside the precast concrete pile body (80), and the precast concrete pile body (80) is provided with the large nut (2) at one end. The large nut (2) is provided with the snap-fit ​​mechanism and the pre-tightening nut (4). The other end of the precast concrete pile body (80) is equipped with the insertion rod (1). The end of the precast concrete pile body (80) is provided with a drive component receiving groove (82). When two adjacent precast concrete piles are connected, one end of the drive component receiving groove (82) is connected to the outer wall of the precast concrete pile body (80), and the other end extends to the end of the pre-tightening nut (4). After the drive component (6) is inserted into the drive component receiving groove (82) from the outer wall of the precast concrete pile body (80), the drive component (6) can interact with the intermediate sleeve (5) provided on the pre-tightening nut (4), so that the pre-tightening nut (4) rotates and moves along the axial direction of the large nut (2), thereby locking the plug (10) and the snap-fit ​​mechanism in the axial direction of the large nut (2).

16. The precast concrete pile according to claim 15, characterized in that: The precast concrete pile body (80) is provided with a small nut (21) at one end of the insert rod (1). One end of the large nut (2) and the small nut (21) are respectively connected to the two ends of the main reinforcement (81). The insert rod (1) is threadedly connected to the other end of the small nut (21).

17. The precast concrete pile according to claim 15, characterized in that: After the drive component (6) drives the intermediate sleeve to rotate and locks the plug (10) and the snap-fit ​​mechanism in the axial direction of the large nut (2), the drive component (6) remains in or is removed from the drive component receiving groove (82).

18. The precast concrete pile according to claim 15, characterized in that: Structural adhesive is also injected into the connecting end face of the precast concrete pile body (80) and the pre-tightening mechanical joint with intermediate sleeve.

19. A method for connecting precast concrete piles according to any one of claims 15 to 18, characterized in that: Includes the following steps: The end of the precast concrete pile with the insertion rod and the end of the adjacent precast concrete pile with the pre-tightening nut are moved relative to each other, and the plug of the insertion rod is inserted into the insertion cavity of the pre-tightening nut to achieve the snap-fit ​​between the plug and the snap-fit ​​mechanism. A drive component is inserted into the outer wall of a precast concrete pile, and the drive component drives the transmission structure, thereby causing the preload nut to rotate and move axially along the large nut, thereby locking the plug and the snap-fit ​​mechanism in the axial direction of the large nut.

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