A pre-tightening mechanical joint of tooth clamping, precast concrete pile and connecting method

Abstract

The application discloses a pre-tightening mechanical joint of a tooth clamping type, a precast concrete pile and a connecting method. The joint comprises a plug rod with a plug at one end, a large nut provided with a containing cavity and a pre-tightening nut. The outer wall of the plug is provided with first teeth. The pre-tightening nut comprises a pre-tightening nut body and a plurality of elastic clamping pieces provided with second teeth on the inner wall and arranged along the circumference of the pre-tightening nut body. The outer wall of the pre-tightening nut body is provided with a pre-tightening nut connecting part and a driving part. The pre-tightening nut connecting part is connected with the large nut in the containing cavity, and one end of the pre-tightening nut body provided with the elastic clamping pieces is placed in the containing cavity. After the plug is inserted into the pre-tightening nut body and the first and second teeth are clamped, the driving part can drive the pre-tightening nut to rotate and move along the large nut in the axial direction, so that the plug and the pre-tightening nut are locked in the axial direction of the large nut. The axial gap between the plug and the pre-tightening nut is effectively eliminated, the tensile force, the shearing force or the bending force is improved, and cracks will not be generated at the connecting position of the precast concrete pile.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of prefabricated components, in particular to a tooth clamped pre-tightening mechanical joint, a prefabricated concrete pile and a connecting method. BACKGROUND

[0002] Generally, engineering piles (prefabricated piles) are multi-section piles, and the existing prefabricated concrete pile ends are generally connected between piles by mechanical joints.

[0003] In the Technical Standard for Prestressed Concrete Pipe Pile JGJ / T406-2017, Article 5.1.7 provides that for prestressed pipe piles with strict requirements for no cracks, the crack control level should be first grade; Article 5.1.8 provides that when the pipe pile shaft is in tension, the crack control level is first grade; when the pipe pile shaft is in bending, the crack control level of the pipe pile in weak corrosion environment and above is second grade, and the crack control level of the pipe pile in medium and strong corrosion environment and above is first grade.

[0004] In the Code for Design of Concrete Structures GB50010-2015, Article 3.4.4 provides that the stress crack control level of the normal section of the structural member is divided into three grades, and the grade division and requirements should comply with the following provisions:

[0005] First grade - members with strict requirements for no cracks, when calculated according to load standard combination, the tensile edge concrete of the member should not produce tensile stress.

[0006] Second grade - members with general requirements for no cracks, when calculated according to load standard combination, the tensile stress of the tensile edge concrete of the member should not be greater than the standard value of the tensile strength of the concrete.

[0007] Third grade - members allowed to have cracks: for reinforced concrete members, when calculated according to load quasi-permanent combination considering the influence of long-term action, the maximum crack width of the member should not exceed the maximum crack width limit value specified in Table 3.4.5 of the present specification. For prestressed concrete members, when calculated according to load standard combination and considering the influence of long-term action, the maximum crack width of the member should not exceed the maximum crack width limit value specified in Table 3.4.5 of the present specification; for prestressed concrete members in Class 2a environment, they should also be calculated according to load quasi-permanent combination, and the tensile stress of the tensile edge concrete of the member should not be greater than the standard value of the tensile strength of the concrete. In the provisions of Table 3.4.5 of the present specification, it is specified that the crack control level of prestressed concrete structures in Class 3a and 3b environments is first grade, and the crack control level in Class 2b environment is second grade. The first and second crack control levels do not allow cracks to occur. The crack control level in Class 2a environment is third grade, with a maximum crack width limit of 0.1mm, and the crack control level in Class 1 environment is third grade, with a maximum crack width limit of 0.2mm.

[0008] As Figure 23 The first structure of the existing mechanical joint is shown, which includes a large nut 2, a small nut 21, a plug rod 1 and a connecting piece 90; one end of the plug rod is threadedly connected with the small nut, and the other end is provided with a plug; the connecting piece is threadedly connected with the large nut, and one end of the connecting piece arranged in the large nut is provided with a plurality of elastic clamping pieces; the plug is inserted from one end of the connecting piece and can abut against the elastic clamping pieces, thereby achieving clamping connection of the plug rod and the connecting piece, so that the mechanical joint can realize quick connection of two sections of precast concrete piles. However, the mechanical joint for connecting precast concrete piles has the following disadvantages: 1. When the mechanical joint is used to connect precast concrete piles, the plug rod may be over-inserted into the connecting piece due to the inclination of the pile end face and other reasons. When the plug rod is over-inserted into the connecting piece, the entire or partial mechanical joint at the connecting end face of the precast concrete pile will produce an axial gap under the action of pulling force, shearing force or bending force, thereby causing an axial gap at the connecting position of the precast concrete pile, and cracks at the connecting position of the precast concrete pile, specifically, as Figure 23 The plug of the plug rod is over-inserted into the connecting piece, and an axial gap Δh is formed between the end of the elastic clamping piece and the blocking surface of the plug, so that an axial gap is also formed between the connecting end faces of the precast concrete pile under the action of external force, so that it cannot meet the requirements of the "Technical Standard for Prestressed Concrete Pipe Piles" JGJ / T406-2017, i.e., the crack control level of the prestressed pipe pile should be first level according to the provisions of Article 5.1.7; the crack control level is first level according to the provisions of Article 5.1.8 when the pipe pile body is subjected to axial tension; the crack control level of the pipe pile in weak corrosion environment and above is second level, and the crack control level of the pipe pile in medium and strong corrosion environment and above is first level; 2. Since the large nut and the connecting piece are connected by threads, and the small nut and the plug rod are connected by threads, there is a certain axial gap between the threads, and the axial gap of the threads will also cause an axial gap between the connecting end faces of the precast concrete pile when the mechanical joint is subjected to pulling force, thereby increasing the size of the cracks at the connecting position of the precast concrete pile, so that it cannot meet the crack control requirements in the "Technical Standard for Prestressed Concrete Pipe Piles"; 3. As shown in Figure 24 When the mechanical joint is used to connect the precast concrete pile, the plug of the plug rod is under-inserted into the connecting piece, i.e., the end of the elastic clamping piece does not enter the ring groove of the plug rod when the plug rod is inserted into the connecting piece, so that the plug rod and the connecting piece cannot be clamped, thereby causing failure of the pile connection.

[0009] As Figure 25The second structure of the existing mechanical joint is shown, which comprises a large nut 2, a small nut 21, a plug rod 1, an intermediate nut 91, an elastic member 92 and a card 93. One end of the plug rod is threadedly connected with the small nut, the other end is provided with a plug, the intermediate nut is threadedly connected with the large nut, the intermediate nut is arranged at one end of the large nut and is provided with a tapered clamping surface, the elastic member and a plurality of cards are arranged in the accommodating cavity of the large nut, the elastic member abuts the plurality of cards on the tapered clamping surface of the intermediate nut, the plug is inserted into one end of the intermediate nut and can compress the elastic member, so that the plug passes through the space surrounded by the plurality of cards to be clamped between the intermediate nut and the plug, so as to realize the rapid connection of two sections of precast concrete piles. However, the following problems exist in the connection of the precast concrete piles by using the mechanical joint: 1. During the process of inserting the plug rod into the intermediate nut, the central axis x-x of the plug rod is different from the central axis y-y of the intermediate nut, so that, as shown in Figure 25 、 Figure 26 and Figure 27 , during the process of inserting the plug rod into the intermediate nut, the card close to the axis of the plug rod is first contacted with the plug, and the card far away from the axis of the plug rod is contacted with the plug later, the lower card is first contacted with the plug and is compressed by the spring under the action of the plug, and the upper card is contacted with the plug later, so that, as shown in Figure 26 , one side of the card enters between the plug and the intermediate nut, and the other side of the card cannot enter between the plug and the intermediate nut; or, as shown in Figure 27 , the clamping positions of the plurality of cards and the plug and the intermediate nut are different, thereby causing the pile connection failure or the low connection strength of the mechanical joint, so that, when the precast concrete pile is subjected to the pulling force, the shearing force or the bending force, the axial slip occurs between the plug rod and the card of the mechanical joint, thereby causing the axial gap of the whole or part of the mechanical joint at the pile connection end surface, and the cracking of the mechanical joint connection of the precast concrete pile; 2. After the plug is inserted into the intermediate nut and clamped with the card, the plug, the card and the intermediate nut do not form the complete fitting of the wedge surface (the force between the plug and the card is very small), so that, when the plug rod is subjected to the pulling force, the shearing force or the bending force, the plug of the plug rod will extrude the card, thereby causing the axial slip of the card relative to the plug, so that, when the precast concrete pile is connected by using the mechanical joint, the axial gap of the whole or part of the mechanical joint at the pile connection end surface will be caused when the precast concrete pile is subjected to the pulling force, the shearing force or the bending force, thereby causing the axial gap of the precast concrete pile connection, and the cracking of the mechanical joint connection of the precast concrete pile; 3. As shown in Figure 26 , the clamping surfaces of the card and the plug are both tapered cylindrical surfaces, and the clamping positions of the card and the plug are uncertain, so that, when the card is clamped with the plug, the clamping surfaces of the card and the plug do not completely fit. As shown in Figure 28As shown in the figure, Q1 to Q5 curves represent the cross-sectional radius curves of the clamping surface of the plug at different positions, and J curve represents the cross-sectional radius curve of the card at a certain position. As shown in the figure, when J curve is at Q1 position, J curve completely matches Q1, and when J curve is at Q2 to Q5, the gap between J curve and Q curve gradually increases, that is, when the card is at different positions of the plug, the clamping state of the card and the plug is different, that is, it cannot be guaranteed that the clamping surface of the card completely matches the clamping surface of the plug. That is, the card and the plug are in line contact, and when the mechanical joint is subjected to pulling force, shearing force or bending force, axial slip occurs between the card and the plug or the card is partially embedded into the plug (or the card is deformed under force), thereby causing axial gap of the mechanical joint. That is, when the mechanical joint is used for connecting precast concrete piles, axial gap also occurs between the connecting end surfaces of the precast concrete piles under the action of pulling force, shearing force or bending force, so that cracks occur at the connecting position of the mechanical joint of the precast concrete pile; 4. Since the large nut and the intermediate nut are connected by threads, and the small nut and the plug are connected by threads, the axial gap of the threaded connection also causes the axial gap between the connecting end surfaces of the precast concrete piles under the action of pulling force, shearing force or bending force, so that cracks occur at the connecting position of the mechanical joint of the precast concrete pile. The mechanical structure has the above-mentioned various deficiencies, therefore, when the mechanical joint is used for connecting precast concrete piles, it is easy to cause the precast concrete pile connection to fail to meet the requirements of "Prestressed Concrete Pipe Pile Technical Standard" JGJ / T406-2017, which stipulates that the crack control level of prestressed pipe piles with strict requirements should be first level; the crack control level of pipe pile body under axial tension is first level; the crack control level of pipe pile body under bending is second level in weak corrosion environment and above; the crack control level of pipe pile in medium and strong corrosion environment and above is first level.

[0010] The existing mechanical joint has the problem of axial gap, so that when the precast concrete pile is connected by using the mechanical joint, the connecting mechanism of the above-mentioned mechanical joint of the precast concrete pile will produce gap under the action of pulling force, shearing force and / or bending force, so that cracks occur at the joint of the precast concrete pile. The precast pile foundation is a hidden underground engineering, and the precast pile itself cannot be repaired.

[0011] Safety hazards of building pile foundation caused by cracks in the joint of the precast concrete pile:

[0012] When the precast concrete pile bears the bending resistance and the shearing force, the axial gap of the mechanical joint at the joint of the precast concrete pile causes cracks at the joint, which further causes the pile and the pile to be not on the same axis, and makes the local eccentric force on the connecting end surface of the pile; the concrete at the end surface of the pile is damaged or cracked, and the building pile foundation has a safety hazard.

[0013] When the precast concrete pile bears the tension, the axial gap caused by the mechanical joint cannot be ensured to be completely consistent, and the axial tension bearing capacity design value of the precast pile is considered according to the number of main reinforcement (the number of mechanical joints); the mechanical joint is broken one by one when it bears the tension, and the building pile foundation has a safety hazard.

[0014] When the precast concrete pile bears the bending resistance, the shearing force and the tension, the axial gap at the joint of the precast concrete pile causes cracks at the joint, which causes the underground water to corrode the mechanical connecting piece and / or the main reinforcement of the precast pile, and makes it difficult to guarantee the durability of the precast pile. Specifically, according to the annual corrosion rate of steel pile in Table 4.1.18 of the Technical Code for Building Pile Foundation - JGJ94-2008, when the steel pile is above the ground and in the environment without corrosive gas or corrosive volatile medium, the single-side corrosion rate is 0.05-0.1mm / y; when the steel pile is below the ground and above the water level, the single-side corrosion rate is 0.05mm / y; when the steel pile is below the ground and below the water level, the single-side corrosion rate is 0.03mm / y; when the steel pile is below the ground and in the water level fluctuation area, the single-side corrosion rate is 0.1-0.3mm / y; therefore, when the precast concrete pile has cracks due to the axial gap of the mechanical joint, the mechanical joint and / or the main reinforcement will be rapidly corroded, which makes it difficult to guarantee the durability of the precast pile, and the severity of the harm is self-evident. SUMMARY

[0015] The present application aims at the problem that the axial gap caused by the existing mechanical joint connection mechanism causes cracks at the joint of the precast concrete pile, which causes the corrosion of the main reinforcement and / or the mechanical joint, the local compression of the pile end surface and other problems, and proposes a tooth clamping pre-tightening mechanical joint to solve the problem of the safety hazard caused by the axial gap of the existing mechanical joint connection.

[0016] The technical means adopted by the present application are as follows:

[0017] A tooth clamping pre-tightening mechanical joint, comprising,

[0018] A plug rod, one end of the plug rod is a plug, and the outer wall of the plug is provided with first teeth;

[0019] A large nut, the large nut is provided with a containing cavity;

[0020] The pre-tightening nut comprises a sleeve structure pre-tightening nut body and a plurality of elastic tabs arranged on one end of the pre-tightening nut body and along the circumference of the pre-tightening nut body, the outer wall of the pre-tightening nut body is provided with a pre-tightening nut connecting part and a pre-tightening nut driving part, and the inner wall of the elastic tab is provided with a second tooth;

[0021] The pre-tightening nut connecting part is arranged in the accommodating cavity and is threadedly connected with the large nut, so that one end of the pre-tightening nut body provided with the elastic tab is arranged in the accommodating cavity, and at least part of the pre-tightening nut driving part is arranged outside the accommodating cavity.

[0022] The plug can be inserted into the pre-tightening nut body and make the first tooth and the second tooth radially clamped to realize the clamping of the plug and the pre-tightening nut.

[0023] When the first tooth and the second tooth are radially clamped, the driving part can drive the pre-tightening nut driving part from the side of the pre-tightening nut, so that the pre-tightening nut rotates and moves axially along the large nut, thereby locking the plug and the pre-tightening nut in the axial direction of the large nut.

[0024] Further, the pre-tightening nut driving part is provided with a driving tooth, and the driving part is a lead screw provided with a meshing tooth capable of meshing with the driving tooth.

[0025] Further, the driving tooth is a straight tooth parallel to the pre-tightening nut axis or an inclined tooth at an angle to the pre-tightening nut axis.

[0026] Further, it further comprises a positioning sleeve arranged in the accommodating cavity for correcting the plug during the process of inserting the plug into the accommodating cavity.

[0027] Further, the positioning sleeve is arranged between one end of the pre-tightening nut arranged in the large nut and the bottom surface of the accommodating cavity, and the positioning sleeve is provided with a positioning hole, the inner diameter of the positioning hole is greater than or equal to the outer diameter of the plug and less than the inner diameter formed by the tooth top of the second tooth.

[0028] Further, the first clamping tooth and the second clamping tooth are helical teeth that clamped with each other.

[0029] Further, the pitch of the first tooth is different from the pitch of the pre-tightening nut connecting part.

[0030] Further, the rotation direction of the first tooth is opposite to the thread direction of the pre-tightening nut connecting part.

[0031] Further, the first clamping tooth and the second clamping tooth are sawtooth teeth.

[0032] Further, the diameter of the top of the second tooth is greater than the diameter of the root of the first tooth when the elastic card is in a free state.

[0033] Further, the threaded connection between the pre-tightening nut and the large nut is a loose threaded connection before the plug and the pre-tightening nut are locked in the axial direction of the large nut.

[0034] Further, the tensile strength of the connection between the plug and the pre-tightening nut is greater than or equal to the tensile strength of any of the main reinforcement, the large nut, and the small nut after the plug and the pre-tightening nut are locked in the axial direction of the large nut.

[0035] Further, a small nut is further included for connection with the plug base of the plug rod.

[0036] A precast concrete pile includes a precast concrete pile body, a main reinforcement, and a tooth clamping pre-tightening mechanical joint according to any one of claims 1 to 13.

[0037] The main reinforcement is arranged in the precast concrete pile body, and the precast concrete pile body has the large nut at one end, and the pre-tightening nut is threadedly connected in the large nut.

[0038] The other end of the precast concrete pile body is provided with the plug rod.

[0039] The end of the precast concrete pile body is provided with a driving component accommodating groove.

[0040] When two adjacent precast concrete piles are connected, one end of the driving component accommodating groove is in communication with the outer wall of the precast concrete pile body, and the other end extends to the end of the locking nut, so that after the driving component is inserted into the driving component accommodating groove from the outer wall of the precast concrete pile body, the driving component can interact with the pre-tightening nut driving part, so that the pre-tightening nut rotates and moves in the axial direction of the large nut, thereby locking the plug and the pre-tightening nut in the axial direction of the large nut.

[0041] Further, one end of the precast concrete pile body provided with the plug rod is further provided with a small nut, and one end of the large nut and the small nut is connected with two ends of the main reinforcement, respectively, and the other end of the plug rod is threadedly connected with the small nut.

[0042] Further, after the driving component drives the pre-tightening nut to rotate and lock the plug and the pre-tightening nut in the axial direction of the large nut, the driving component remains in or moves out of the driving component accommodating groove.

[0043] Further, the connecting end surface of the prefabricated concrete pile body and the pre-tightening mechanical joint of the tooth clamping are also injected with structural glue.

[0044] A connecting method of the prefabricated concrete pile disclosed by the present application comprises the following steps:

[0045] The end of the prefabricated concrete pile provided with the insertion rod is moved relative to the end of the adjacent prefabricated concrete pile provided with the pre-tightening nut, and the plug of the insertion rod is inserted into the insertion cavity of the pre-tightening nut to realize the clamping of the plug and the pre-tightening nut.

[0046] The insertion rod is inserted into the driving part of the prefabricated concrete pile, and the pre-tightening nut driving part is driven by the driving part, so that the pre-tightening nut rotates and moves axially along the large nut, thereby locking the plug and the pre-tightening nut in the axial direction of the large nut.

[0047] Compared with the prior art, the pre-tightening mechanical joint of the tooth clamping disclosed by the present application has the following beneficial effects: the pre-tightening mechanical joint of the tooth clamping disclosed by the present application is provided with a pre-tightening nut driving part, and after the plug of the insertion rod 1 is inserted into the insertion cavity of the pre-tightening nut and radially clamped with the elastic clamping piece of the pre-tightening nut placed in the accommodating cavity, the driving part is driven from the side of the pre-tightening nut, so that the pre-tightening nut moves axially along the large nut, thereby locking the plug and the pre-tightening nut in the axial direction of the large nut, thereby effectively eliminating the axial gap between the plug and the pre-tightening nut. Further, since the pre-tightening nut and the insertion rod are locked in the axial direction, a certain axial force (tightening force) is generated in the axial direction during the locking process of the pre-tightening nut, the insertion rod and the clamping mechanism. Under the action of the axial force, the axial gaps between the pre-tightening nut, the insertion rod, the large nut and the small nut and other components can be effectively eliminated, so that when the prefabricated concrete pile is connected by using the mechanical joint disclosed by the present application, the prefabricated concrete pile connection will not crack and generate cracks when subjected to pulling force, shearing force or bending force and other forces, so that when the prefabricated concrete pile is connected by using the mechanical joint disclosed by the present application, the relevant requirements for crack grade control in the Technical Standard for Prestressed Concrete Pipe Pile JGJ / T406-2017 can be met. The problem of cracks at the joint of the prefabricated concrete pile caused by the gap generated by the connection mechanism of the existing mechanical joint is eliminated, and the safety hidden danger of the building pile foundation is eliminated. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 It is an axial view of the pre-tightening mechanical joint of the tooth clamping disclosed by the present application.

[0049] Figure 2 It is a front view of the pre-tightening mechanical joint of the tooth clamping disclosed by the present application.

[0050] Figure 3 A sectional view of the tooth clamped pre-tightening mechanical joint disclosed by the present application;

[0051] Figure 4 A schematic diagram of the tooth clamped pre-tightening mechanical joint disclosed by the present application when the plug and the clamping mechanism are not axially locked after the plug is inserted into the pre-tightening nut;

[0052] Figure 5 A schematic diagram of the tooth clamped pre-tightening mechanical joint disclosed by the present application when the plug and the clamping mechanism are axially locked after the plug is inserted into the pre-tightening nut; Figure 4 A partial enlarged view of A in the above figure;

[0053] Figure 6 A schematic diagram of the tooth clamped pre-tightening mechanical joint disclosed by the present application when the plug and the clamping mechanism are axially locked after the plug is inserted into the pre-tightening nut;

[0054] Figure 7 A partial enlarged view of B in the above figure; Figure 4

[0055] Figure 8 A schematic diagram of the pre-tightening nut of the tooth clamped pre-tightening mechanical joint disclosed by the present application;

[0056] Figure 9 A sectional view of the pre-tightening nut of the tooth clamped pre-tightening mechanical joint disclosed by the present application;

[0057] Figure 10 A top view of the pre-tightening nut of the tooth clamped pre-tightening mechanical joint disclosed by the present application;

[0058] Figure 11 A top view of the positioning sleeve of the tooth clamped pre-tightening mechanical joint disclosed by the present application;

[0059] Figure 12 A sectional view of the positioning sleeve of the tooth clamped pre-tightening mechanical joint disclosed by the present application;

[0060] Figure 13 A front view of the driving component of the tooth clamped pre-tightening mechanical joint disclosed by the present application;

[0061] Figure 14 A right view of the driving component of the tooth clamped pre-tightening mechanical joint disclosed by the present application;

[0062] Figure 15 A front view of the large nut of the tooth clamped pre-tightening mechanical joint disclosed by the present application;

[0063] Figure 16 A sectional view of the large nut of the tooth clamped pre-tightening mechanical joint disclosed by the present application;

[0064] Figure 17 A structural diagram of the insertion rod of the tooth clamped pre-tightening mechanical joint disclosed by the present application;​

[0065] Figure 18 Structure diagram of precast concrete pile connection with the pre-tightening mechanical joint of the tooth clamping disclosed by the present application, the number of piles in the diagram is two sections;

[0066] Figure 19 Sectional view of precast concrete pile connection with the pre-tightening mechanical joint of the tooth clamping disclosed by the present application;

[0067] Figure 20 End view of precast concrete pile connection with the pre-tightening mechanical joint of the tooth clamping disclosed by the present application; Figure 19 Partial enlarged view at D in the diagram;

[0068] Figure 21 End view of precast concrete pile connection with the pre-tightening mechanical joint of the tooth clamping disclosed by the present application;

[0069] Figure 22 Partial enlarged view at F in the diagram; Figure 21 Partial enlarged view at F in the diagram;

[0070] Figure 23 Structure diagram of the existing first mechanical joint, the plug is in the over-insertion state in the diagram;

[0071] Figure 24 Structure diagram of the existing first mechanical joint, the plug is in the under-insertion state in the diagram;

[0072] Figure 25 Structure diagram of the existing second mechanical joint, the plug axis and the middle nut axis are not collinear in the diagram, which is a schematic diagram of the plug-in process;

[0073] Figure 26 Structure diagram of the existing second mechanical joint, the plug of the plug-in rod first contacts the lower card, so that the lower card cannot enter between the plug and the middle nut;

[0074] Figure 27 Structure diagram of the existing second mechanical joint, the multiple cards are clamped at different positions between the plug and the middle nut;

[0075] Figure 28 Schematic diagram of the contact state between the card and the plug clamping surface of the existing second mechanical joint.

[0076] In the diagram: 1, plug-in rod; 10, plug; 11, first tooth; 12, plug-in rod base; 2, large nut; 20, accommodating cavity; 21, small nut; 4, pre-tightening nut; 40, pre-tightening nut body; 41, elastic card; 43, pre-tightening nut driving part; 44, second tooth; 45, insertion cavity; 46, driving tooth; 5, driving part; 50, screw rod; 7, positioning sleeve; 70, positioning hole; 80, precast concrete pile body; 81, main reinforcement; 82, driving part accommodating groove. DETAILED DESCRIPTION

[0077] Embodiment 1

[0078] As shown in Figure 1 , Figure 2 and Figure 3 , the pre-tightening mechanical joint of tooth clamping of the present application comprises,

[0079] a plug rod 1, one end of the plug rod 1 being a plug 10, an outer wall of the plug being provided with a first tooth 11, as shown in Figure 17 ;

[0080] a large nut 2, a structure of the large nut 2 being as shown in Figure 15 , Figure 16 , the large nut 2 being provided with a containing cavity 20;

[0081] a pre-tightening nut 4, as shown in Figure 8 and Figure 9 , the pre-tightening nut 4 comprising a sleeve structure pre-tightening nut body 40 and a plurality of elastic clamping pieces 41 arranged along a circumference of the pre-tightening nut body and disposed at one end of the pre-tightening nut body, an outer wall of the pre-tightening nut body being provided with a pre-tightening nut connecting part 42 and a pre-tightening nut driving part 43, an inner wall of the elastic clamping piece being provided with a second tooth 44;

[0082] the pre-tightening nut connecting part 42 being disposed in the containing cavity 20 and being threadedly connected with the large nut 2, so that one end of the pre-tightening nut body 40 provided with the elastic clamping piece 41 is placed in the containing cavity 20, and at least part of the pre-tightening nut driving part 43 is located outside the containing cavity 20;

[0083] the plug 10 being capable of being inserted into the pre-tightening nut body 40 and making the first tooth 11 radially clamped with the second tooth 44 to realize the clamping of the plug 10 with the pre-tightening nut 4; when the first tooth 41 is radially clamped with the second tooth 44, the driving member 5 is capable of driving the pre-tightening nut driving part 43 from the side of the pre-tightening nut 4, so that the pre-tightening nut 4 rotates and moves axially along the large nut 2, thereby locking the plug 10 with the pre-tightening nut in the axial direction of the large nut 2.

[0084] The pre-tightening mechanical joint of tooth clamping of the present application, as shown in Figure 4 and Figure 6 , the driving member 5 is capable of driving the pre-tightening nut 4 from the side of the pre-tightening nut 4 after the plug 10 of the plug rod 1 is inserted into the insertion cavity 45 of the pre-tightening nut 4 and radially clamped with the elastic clamping piece 41 of the pre-tightening nut 4 placed in the containing cavity 20, to realize the axial locking of the pre-tightening nut with the plug, specifically, as shown in Figure 4This schematically illustrates the movement process. After the plug is inserted into the locking nut, there is a certain axial gap L between the second tooth 44 on the inner side of the elastic clip 41 of the pre-tightening nut 4 and the snap-fit ​​surface of the plug (e.g., ...). Figure 5 As shown), the driving component 5 rotates under the action of an external force (the direction of movement of the driving component 5 is as shown). Figure 4 (As indicated by arrow B), causing the preload nut 4 to rotate ( Figure 4 (As indicated by the middle arrow C) and moves axially along the large nut 2. Figure 4 (As indicated by arrow E), thereby locking the plug 10 and the pre-tightening nut 4 in the axial direction of the large nut 2. That is, after the plug 10 of the insertion rod 1 is engaged with the pre-tightening nut 4, the pre-tightening nut 4 can move along the axial direction of the large nut 2 under the drive of the driving component 5, thereby eliminating the axial gap L between the plug 10 and the pre-tightening nut 4 through the axial movement of the pre-tightening nut 4. Figure 5 and Figure 7 As shown; furthermore, since the preload nut and the insert rod 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 preload nut and the insert rod to 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, and small nut can be effectively eliminated. For example, the gap between the threaded connection of the preload nut and the large nut (the axial gap of the threaded connection in area E2 of the figure), and 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). The mechanical joint disclosed in this invention addresses the gaps between the plug and the pre-tightening nut, ensuring that the precast concrete pile connection will not crack under tensile, shear, or bending forces. This means the mechanical joint provides high tensile, bending, and shear resistance, meeting the crack level control requirements of the "Technical Standard for Prestressed Concrete Pipe Piles" JGJ / T406-2017. Furthermore, it eliminates the safety hazards associated with existing mechanical joints that create gaps in precast concrete pile connections, leading to cracks at the joint.

[0085] Meanwhile, in this invention, since the plug and the pre-tightening nut are engaged by teeth, the axial gap between the plug and the pre-tightening nut is less than the distance of one tooth before the plug is inserted into the pre-tightening nut and the plug and the pre-tightening nut are axially locked. That is, the axial gap between the plug and the pre-tightening nut is relatively small. Therefore, when driving the pre-tightening nut to move axially, the pre-tightening nut only needs to move a small distance axially to quickly achieve the axial locking of the plug and the pre-tightening nut.

[0086] Further, as shown in Figure 8 , Figure 10 , the pre-tightening nut driving part 43 is provided with driving teeth 46, and the driving part 5 is a screw rod 50, which is provided with engaging teeth 50 capable of engaging with the driving teeth 46. The screw rod 5 can be engaged with the engaging teeth from the side of the pre-tightening nut 4 to drive the pre-tightening nut 4 to rotate. The structure of the screw rod (driving part) 5 is shown in Figure 13 , Figure 14 . The driving teeth 46 can be directly machined on the pre-tightening nut driving part, or can be a separate structure, that is, the pre-tightening nut driving part is sleeved with an intermediate sleeve, and the intermediate sleeve is provided with driving teeth (forming a gear-like structure), and the intermediate sleeve is connected with the pre-tightening nut driving part through a key or other structure.

[0087] The pre-tightening nut body 40 is provided with an insertion cavity 45 for inserting the plug 10 of the insertion rod 1. The outer wall of the pre-tightening nut body 40 includes a pre-tightening nut connecting part 42 provided with external threads for threaded connection with the large nut 2, and a pre-tightening nut driving part 43 provided with driving teeth 46 for engaging with the engaging teeth on the screw rod to drive the pre-tightening nut 4 to rotate. One end of the precast concrete pile 8 is provided with a driving part accommodating groove 82 communicating with the outer wall of the pile. The other end of the driving part accommodating groove 82 extends to the end of the large nut 2. The driving part accommodating groove 52 can insert the screw rod 5 between the two sections of the precast concrete pile, and can make the screw rod 5 engage with the driving teeth 46 on the pre-tightening nut driving part 43 outside the large nut 2. The driving of the screw rod 5 is carried out at the outer side wall of the precast concrete pile 8. In this embodiment, the end of the screw rod 50 is provided with an internal hexagonal hole, a straight slot or a cross-shaped slot, etc. to facilitate the driving of the screw rod by a tool. The rotation of the screw rod can drive the pre-tightening nut to rotate through the rotation of the pre-tightening nut driving part 43 (the structure of the driving teeth 46 on the pre-tightening nut driving part), and then realize the axial movement of the pre-tightening nut to lock the plug and the elastic clamping piece 41 of the pre-tightening nut 4 in the axial direction, and eliminate the axial gap between the plug of the insertion rod and the pre-tightening nut and other components. The pre-tightening nut is driven to rotate by the screw rod tooth structure, which not only has a simple structure, but also has a large stroke, so that the pre-tightening nut can move a larger stroke in a smaller space, ensuring the locking performance.

[0088] Further, the driving teeth are straight teeth parallel to the axis of the pre-tightening nut. Because the precision of the teeth is high and the matching precision between the gears is high, the straight tooth transmission speed is stable and the operation is smooth. The simple structure of the straight tooth transmission also makes it more reliable and has a longer service life.

[0089] In the embodiment, the driving teeth are helical teeth which can also be arranged at an angle to the axis of the pre-tightening nut. The helical gear teeth mesh with the screw rod teeth. The helical structure allows the screw rod to apply a greater circumferential driving force to the pre-tightening nut, thereby facilitating the rotation of the pre-tightening nut to achieve axial movement.

[0090] Further, as shown in Figure 3 , the device further comprises a positioning sleeve 7 arranged in the accommodating cavity 20 for correcting the plug rod 1 during the process of inserting the plug rod 1 into the accommodating cavity 20. By arranging the positioning sleeve 7 in the accommodating cavity 20 for correcting the plug rod 1 during the process of inserting the plug rod 1 into the accommodating cavity 20, the axis of the plug rod 1 can be made to substantially coincide with or be substantially parallel to the axis of the large nut 2, thereby reducing or eliminating the contact between the plug rod 1 and the pre-tightening nut 4 in the radial direction during the process of inserting the plug rod 1 into the pre-tightening nut 4 and / or after the plug rod 1 is inserted into the pre-tightening nut 4, i.e. reducing the force between the plug rod 1 and the pre-tightening nut 4, so as to facilitate the rotation of the pre-tightening nut 4 driven by the driving component 5 from the side, thereby causing the pre-tightening nut 4 to move axially along the large nut 2, and locking the plug 10 and the pre-tightening nut 4 in the axial direction of the large nut 2.

[0091] Further, the positioning sleeve 7 is arranged between the end of the pre-tightening nut 4 placed in the large nut 2 and the bottom surface of the accommodating cavity 20, and the positioning sleeve 7 is provided with a positioning hole 70, the inner diameter of the positioning hole 70 being greater than or equal to the outer diameter of the plug 10 and smaller than the inner diameter formed by the addendum of the second teeth 44.

[0092] Specifically, in the embodiment, as shown in Figure 3 , Figure 11 , and Figure 12As shown, the positioning sleeve 7 is a circular ring structure, preferably the positioning sleeve 7 is a circular ring metal sheet, the outer diameter of the positioning sleeve 7 is provided with a threaded structure, the positioning sleeve 7 can be screwed into the accommodating cavity of the large nut 2, the large nut is provided with an accommodating cavity 20, the inner wall of the accommodating cavity 20 is provided with an internal thread, one end of the large nut can be fixedly connected with the main bar, the other end is connected with 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, the inner diameter of the positioning hole 70 is greater than or equal to the outer diameter of the plug 10 and less than the inner diameter formed by the tooth top of the second tooth 44, and then the plug 10 of the insertion rod 1 passes through the insertion cavity 40 of the pre-tightening nut 4, the plug 10 is inserted into the positioning hole 70, because the inner diameter of the positioning hole 70 is greater than or equal to the outer diameter of the plug 10 and less than the inner diameter formed by the tooth top of the second tooth 44, the gap between the positioning hole 70 and the plug 10 is smaller than the gap between the tooth top of the second tooth and the plug (the tooth root of the first tooth), so that the positioning hole 70 limits and guides the insertion rod 1 during the process of inserting the pre-tightening nut 4 and / or after the insertion rod 1 is inserted into the pre-tightening nut 4, so that the insertion rod 1 and the pre-tightening nut 4 exist a gap (no contact) in the radial direction, that is, the force between the insertion rod and the pre-tightening nut is reduced or eliminated, so as to drive the driving part to drive the pre-tightening nut to rotate from the side, so that the pre-tightening nut moves axially along the large nut, thereby locking the plug and the clamping mechanism 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 pre-tightening nut 4, which is an octagonal hole in the figure; the positioning hole is a polygonal hole, which is convenient for inserting a hexagonal wrench or the like into the positioning hole to screw the positioning sleeve into the large nut.

[0093] The accommodating cavity 20 of the large nut 2 can also be a stepped hole, the hole diameter of the stepped hole close to the bottom surface of the accommodating cavity is smaller, and the hole diameter of the stepped hole close to the opening end is larger. An inner thread for threadedly connecting with the pre-tightening nut 4 is processed on the inner wall of the accommodating cavity 20 close to the opening end (at the stepped hole with a larger hole diameter). A positioning sleeve mounting hole is arranged at the root of the inner thread (i.e. the end of the inner thread towards the bottom surface of the accommodating cavity). The hole diameter of the positioning sleeve mounting hole is larger than the hole diameter of the hole close to the bottom surface of the accommodating cavity and smaller than the hole diameter of the stepped hole close to the opening end. The positioning sleeve 7 is in a circular ring structure, and is preferably a circular ring metal sheet. The outer diameter of the positioning sleeve 7 is in interference fit with the positioning sleeve mounting hole. The positioning sleeve 7 is clamped into the positioning sleeve mounting hole under the action of an external force. The inner diameter hole of the positioning sleeve 7 is a positioning hole 70. The inner diameter of the positioning hole 70 is greater than or equal to the maximum outer diameter of the plug 10 and smaller than the inner diameter of the insertion cavity 40 of the pre-tightening nut 4. Then, after the plug 10 of the insertion 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 inner diameter of the positioning hole 70 is greater than or equal to the outer diameter of the plug 10 and smaller than the inner diameter formed by the addendum of the second tooth 44, the gap between the positioning hole 70 and the plug 10 is smaller than the gap between the plug and the elastic card. Therefore, the positioning hole 70 limits and guides the insertion rod 1 during the process of inserting 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. Thus, the insertion rod 1 and the elastic card have a gap (no contact) in the radial direction, i.e. the force between the insertion rod and the pre-tightening nut is reduced or eliminated, so as to facilitate the driving component to drive the pre-tightening nut to rotate from the side, so that the pre-tightening nut moves in the axial direction of the large nut, thereby locking the plug and the pre-tightening nut 4 in the axial direction of the large nut.

[0094] Further, the first tooth 11 and the second tooth 44 are mutually engaged helical teeth. The pitch of the first tooth 11 is different from the pitch of the pre-tightening nut connecting portion 42. The use of helical teeth for the first tooth 11 and the second tooth 44 can increase the pull-out resistance and thus improve the connection strength of the insertion rod and the pre-tightening nut. At the same time, the pitch of the first tooth 11 is different from the pitch of the pre-tightening nut connecting portion 42, so that when the pre-tightening nut moves in the axial direction of the large nut under the driving of the driving component, the helical teeth between the pre-tightening nut and the large nut and between the plug and the elastic card can form a stroke difference, and thus the tooth surfaces of the first tooth and the second tooth can abut against each other to achieve axial locking of the insertion rod and the pre-tightening nut. The first tooth and the second tooth can also be non-helical teeth. Preferably, the rotation direction of the first tooth is opposite to the rotation direction of the thread of the pre-tightening nut connecting portion. The opposite rotation direction of the first tooth and the thread of the pre-tightening nut connecting portion makes the tooth surfaces of the first tooth and the second tooth more easily abut against each other when the pre-tightening nut rotates and moves in the axial direction of the large nut, and the axial locking effect is better.

[0095] The first tooth 11 and the second tooth 44 can be in the form of different shapes such as a pagoda tooth, a rectangular tooth, or a trapezoidal tooth, and preferably, the first tooth 11 and the second tooth 44 are in the form of a sawtooth. The sawtooth is suitable for working under high load and shear force, has higher tensile strength and more stable connection effect. Because the transverse corrugation of the sawtooth thread is very obvious, it can effectively increase the friction between the threads, improve the self-locking effect of the thread, and better prevent the fastener from loosening. The transverse corrugation of the sawtooth thread not only increases the friction between the threads, but also increases the surface area of the thread, making the fastening effect more reliable and better guaranteeing safety in production.

[0096] Further, when the elastic card 41 is in a free state, the diameter formed by the tooth top of the second tooth 44 is greater than the diameter of the tooth root of the first tooth 11. That is, after the plug rod and the elastic card are radially clamped (before being axially locked), the elastic card and the plug rod do not contact in the radial direction, that is, the force between the plug rod and the pre-tightening nut is reduced or eliminated, so that the driving part drives the pre-tightening nut to rotate from the side, so that the pre-tightening nut moves in the axial direction of the large nut, thereby locking the plug and the clamping mechanism in the axial direction of the large nut.

[0097] Further, before the plug 10 and the pre-tightening nut 4 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 threaded connection. Specifically, the tolerances of the internal threads on the inner wall of the receiving cavity of the large nut and the external threads on the outer wall of the pre-tightening nut can be reasonably selected as needed, so that the threaded connection between the pre-tightening nut and the large nut is a loose threaded connection. Since the pre-tightening nut and the large nut are in a loose threaded connection, the force between the pre-tightening nut and the large nut is relatively small before the plug and the pre-tightening nut 4 are locked, thereby facilitating the driving part 5 to drive the pre-tightening nut to rotate from the side, so that the pre-tightening nut moves in the axial direction of the large nut, thereby locking the plug and the pre-tightening nut 4 in the axial direction of the large nut.

[0098] Further, after the plug 10 and the pre-tightening nut 4 are locked in the axial direction of the large nut 2, the tensile strength of the connection between the plug and the pre-tightening nut is greater than or equal to the tensile strength of any one of the main reinforcement 81, the large nut 2, and the small nut 21.

[0099] Preferably, after the plug 10 and the pre-tightening nut 4 are locked in the axial direction of the large nut 2, the plug and the pre-tightening nut 4 do not undergo ductile deformation when subjected to a pull-out force of 11.7 MPa. In this application, because the plug 10 and the elastic card 41 are locked in the axial direction of the large nut 2, the tensile strength of the plug and the pre-tightening nut 4 connection is greater than or equal to the tensile strength of any one of the main reinforcement, the large nut, and the small nut, and the plug and the elastic card do not undergo ductile deformation when subjected to a pull-out force of 11.7 MPa, the large nut, the small nut, the insert rod, and the locking nut of the precast concrete pile with the pre-tightening mechanical joint disclosed in this invention will not undergo ductile deformation before being subjected to a pull-out force that causes the main reinforcement to undergo ductile deformation. Therefore, no cracks or gaps will be generated 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 disclosed in this invention can reliably connect without being damaged, further ensuring the connection performance of the precast concrete piles connected by the pre-tightening mechanical joint 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 Nt (kN) of the axial tensile bearing capacity of the pile body in terms of the axial compressive strength and flexural bearing capacity of the prestressed concrete square pile. 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, when the pull-out force of the pre-tightened mechanical joint disclosed in this application is within 11.7kN, neither the main reinforcement of the precast concrete pile nor the pre-tightened mechanical joint undergoes ductile deformation, 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.

[0100] Furthermore, it also includes a small nut 21 for connecting to the plug base 12 of the plug 1.

[0101] 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 the two ends of the main reinforcement in the precast concrete pile. The large nut is equipped with a positioning sleeve and a pre-tightening nut, etc., and two adjacent precast concrete piles can be quickly connected by the pre-tightening mechanical joint disclosed in this application.

[0102] Example 2

[0103] like Figure 18 and Figure 19 The image shows a precast concrete pile 8 disclosed in this invention, comprising a precast concrete pile body 80, main reinforcement bars 81, and the toothed snap-fit ​​pre-tightening mechanical joint.

[0104] like Figure 20 As shown, 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, and the pre-tightening nut 4 is internally threaded to the large nut 2; the insertion rod 1 is installed at the other end of the precast concrete pile body 80.

[0105] like Figure 21 , Figure 22 As shown, the end of the precast concrete pile body 80 is provided with a drive component receiving groove 82;

[0106] One end of the drive component receiving groove 82 is connected to the outer wall of the precast concrete pile, and the other end extends to the end of the large nut 2. After the drive component 5 is inserted into the drive component receiving groove 82 from the outer wall of the precast concrete pile, the drive component 5 can interact with the pre-tightening nut drive part, causing the pre-tightening nut 4 to rotate radially and move axially along the large nut 2, thereby locking the plug 10 and the snap-fit ​​mechanism 3 in the axial direction of the large nut 2.

[0107] The toothed snap-fit ​​pre-tightening mechanical connector disclosed in this application, due to the presence of a pre-tightening nut drive part 43, allows the drive component 5 to drive the pre-tightening nut 4 laterally after the plug 10 of the insert rod 1 is inserted into the insertion cavity 45 of the pre-tightening nut 4 and radially snapped with the elastic clip 41 of the pre-tightening nut 4 placed in the receiving cavity 20. This causes the pre-tightening nut to select and 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. In other words, after the plug of the insert rod is snapped with the elastic clip of the pre-tightening nut, the pre-tightening nut can move along the axial direction of the large nut under the drive of the drive component, thereby eliminating the axial gap between the plug of the insert rod and the pre-tightening nut through the axial movement of the pre-tightening nut. Furthermore, since the pre-tightening nut and the insert rod are locked in the axial direction, a certain axial force is generated in the axial direction during the locking process. Under the action of this axial force, the axial gaps between components such as the preload nut, insert rod, large nut, 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 preload nut. 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 5 drives the pre-tightening nut 4 to rotate and locks the plug 10 and the pre-tightening nut in the axial direction of the large nut 2, the driving component 5 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 a single lead screw to achieve axial locking of all mechanical joints, eliminate axial gaps, improve the pull-out resistance of the pile, and the lead screw can be reused, saving usage costs. Alternatively, in the connection of precast concrete piles, each mechanical joint can be driven by a lead screw. After the lead screw drives the pre-tightening nut to rotate and achieves axial locking, the lead screw remains in the driving component receiving groove, that is, the lead screw is not removed from the driving component receiving groove. Since multiple lead screw 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 toothed engagement. 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 method for connecting precast concrete piles disclosed in this invention includes the following steps:

[0113] The end of the precast concrete pile 8 with the insertion rod 1 and the end of the adjacent precast concrete pile with the pre-tightening nut 4 are moved relative to each other, and the plug 10 of the insertion rod 1 is inserted into the insertion cavity 45 of the pre-tightening nut 4 to achieve the snap-fit ​​between the plug and the pre-tightening nut.

[0114] The drive component 5 is inserted into the outer wall of the precast concrete pile 8, and the drive component drives the pre-tightening nut drive part 43, thereby causing 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 pre-tightening nut 4 in the axial direction of the large nut 2. The above method can achieve a gapless connection of the precast concrete pile.

[0115] When the preload nut is driven to rotate via the drive component (lead screw) and the preload nut drive unit, the following two situations may occur: 1. When the force generated by the threaded connection between the preload nut and the large nut is small, i.e., the connection between the preload nut and the large nut is relatively loose, during the process of the lead screw entering the drive component's receiving groove, the teeth on the lead screw and the preload nut drive unit mesh and drive the preload nut to start rotating and move axially along the large nut. When the preload nut achieves axial locking between the locking mechanism and the plug, the preload nut stops rotating. At this time, the lead screw moves into the drive component's receiving groove under the action of the tooth structure until the end of the lead screw abuts against the end of the receiving groove. When the lead screw is continued to be driven, the interaction between the lead screw and the teeth will cause the preload nut to generate a pre-tension force on the plug rod, thereby causing the precast concrete pile connection to... 1. Pre-stress is generated, so that the piles will not buckle under certain forces after connection, thus improving the strength of the precast concrete pile connection; 2. When the force generated by the threaded connection between the pre-tightening nut and the large nut is large, that is, the connection between the pre-tightening nut and the large nut is tight, during the process of the screw entering the drive component receiving groove, the teeth of the screw and the drive part of the pre-tightening nut mesh. At this time, the tooth structure cannot drive the pre-tightening nut to rotate. Under the action of the tooth structure, the screw moves into the receiving groove of the drive component until the end of the screw abuts against the end of the receiving groove. Then, the screw starts to drive the pre-tightening nut to rotate through the tooth structure to achieve axial locking between the locking mechanism and the plug. Thus, the axial movement of the pre-tightening nut eliminates the axial gap between the plug of the insertion rod and the pre-tightening nut, ensuring the strength of the precast pile connection. Furthermore, since the preload nut and the insert rod are locked in the axial direction, a tightening force is generated between the locking nut and the large nut during the locking process. This causes the preload nut and the insert rod to generate a certain axial force in the axial direction. Under the action of this axial force, the axial gaps between the preload nut, the insert rod, the large nut, and the 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 preload nut, etc., further improve the connection performance of the mechanical joint and improve the pull-out resistance of the precast concrete pile after being connected by the preload mechanical joint.

[0116] 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 toothed snap-fit ​​pre-tightening mechanical joint for end connection between precast concrete piles, characterized in that: include, Insert rod (1), one end of the insert rod (1) is a plug (10), and the outer wall of the plug is provided with a first tooth (11); Large nut (2), the large nut (2) is provided with a receiving cavity (20); The preload nut (4) includes a preload nut body (40) with a sleeve structure and a plurality of elastic clips (41) disposed at one end of the preload nut body (40) and arranged circumferentially along the preload nut body (40). The outer wall of the preload nut body (40) is provided with a preload nut connecting part (42) and a preload nut driving part (43). The inner wall of the elastic clips (41) is provided with a second tooth (44). The preload nut connecting part (42) is located inside the receiving cavity (20) and threadedly connected to the large nut (2), such that one end of the preload nut body (40) with the elastic card (41) is placed in the receiving cavity (20), and at least part of the preload nut driving part (43) is located outside the receiving cavity (20); The plug (10) can be inserted into the preload nut body (40) and the first tooth (11) engages with the second tooth (44) to achieve the engagement of the plug (10) with the preload nut (4); When the first tooth (11) engages with the second tooth (44), the drive component (5) can drive the pre-tightening nut drive part (43) from the side of 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 eliminating the gap between the plug (10) and the pre-tightening nut (4) in the axial direction of the large nut (2), and locking the plug (10) and the pre-tightening nut (4) in the axial direction of the large nut (2).

2. The pre-tightening mechanical joint with toothed engagement according to claim 1, characterized in that: The preload nut drive unit (43) is provided with drive teeth (46), and the drive component (5) is a lead screw, which is provided with engagement teeth that can engage with the drive teeth (46).

3. The pre-tightening mechanical joint with toothed engagement according to claim 2, characterized in that: The drive tooth (46) is a straight tooth parallel to the axis of the preload nut (4) or a helical tooth at a certain angle to the axis of the preload nut (4).

4. The pre-tightening mechanical joint with toothed engagement according to any one of claims 1 to 3, 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).

5. The pre-tightening mechanical joint with toothed engagement according to claim 4, characterized in that: The positioning sleeve (7) is located between the end of the pre-tightening nut (4) placed inside the large nut (2) and the bottom surface of the receiving cavity (20). The positioning sleeve (7) is provided with a positioning hole (70). The inner diameter of the positioning hole (70) is greater than or equal to the outer diameter of the plug (10) and less than the inner diameter formed by the tooth tip of the second tooth (44).

6. The pre-tightening mechanical joint with toothed engagement according to claim 1, characterized in that: The first tooth (11) and the second tooth (44) are interlocking spiral teeth.

7. The pre-tightening mechanical joint with toothed engagement according to claim 6, characterized in that: The pitch of the first tooth (11) is different from the pitch of the pre-tightening nut connection (42).

8. The pre-tightening mechanical joint with toothed engagement according to claim 7, characterized in that: The direction of rotation of the first tooth (11) is opposite to the direction of rotation of the thread of the preload nut connection (42).

9. The pre-tightening mechanical joint with toothed engagement according to claim 8, characterized in that: The first tooth (11) and the second tooth (44) are serrated teeth.

10. The pre-tightened mechanical joint with toothed engagement according to claim 1, characterized in that: When the elastic card (41) is in a free state, the diameter formed by the tip of the second tooth (44) is greater than the diameter of the root of the first tooth (11).

11. The pre-tightened mechanical joint with toothed engagement according to claim 1, characterized in that: Before the plug (10) and the pre-tightening nut (4) 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.

12. The pre-tightening mechanical joint with toothed engagement according to claim 1, characterized in that: After the plug (10) and the pre-tightening nut (4) are locked in the axial direction of the large nut (2), the tensile strength of the connection between the plug and the pre-tightening nut is greater than or equal to the tensile strength of any one of the main rib (81), the large nut (2) and the small nut (21).

13. The pre-tightened mechanical joint with toothed engagement 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).

14. A precast concrete pile, characterized in that: Includes a precast concrete pile body (80), main reinforcement (81), and a pre-tightened mechanical joint with toothed interlocking as described in any one of claims 1 to 13; 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, and the large nut (2) is internally threaded with 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 (5) is inserted into the drive component receiving groove (82) from the outer wall of the precast concrete pile body (80), the drive component (5) can interact with the pre-tightening nut drive part (43), 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 pre-tightening nut in the axial direction of the large nut (2).

15. The precast concrete pile according to claim 14, 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).

16. The precast concrete pile according to claim 14, characterized in that: After the drive component (5) drives the preload nut (4) to rotate and locks the plug (10) and the preload nut (4) in the axial direction of the large nut (2), the drive component (5) remains in or is removed from the drive component receiving groove (82).

17. The precast concrete pile according to claim 14, 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 toothed engagement.

18. A method for connecting precast concrete piles according to any one of claims 14 to 17, characterized in that: Includes the following steps: Move one end of the precast concrete pile (8) with the insert rod (1) relative to the end of the adjacent precast concrete pile with the pre-tightening nut (4), and insert the plug (10) of the insert rod (1) into the insertion cavity (45) of the pre-tightening nut (4) to achieve the snap-fit ​​between the plug and the pre-tightening nut. The drive component (5) is inserted into the outer wall of the precast concrete pile (8), and the drive component (5) drives the pre-tightening nut drive part (43), thereby causing 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 pre-tightening nut (4) in the axial direction of the large nut (2).

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