Dumbbell bolt pin pipe pile connector and design method thereof

Abstract

The invention relates to a dumbbell bolt pin pipe pile connector and a design method thereof.The dumbbell bolt pin pipe pile connector comprises an upper pipe pile section, a lower pipe pile section, an upper end plate, a lower end plate and dumbbell bolt pins, and a plurality of evenly-distributed prestressed tendon anchoring holes are formed in the upper end plate and the lower end plate along the circumference; an opening is formed between every two adjacent prestressed tendon anchoring holes, cover plates are arranged at the positions, located at the openings, of the upper end plate and the lower end plate and seal the openings to form T-shaped grooves, every two corresponding T-shaped grooves are in butt joint to form an I-shaped bolt pin groove, a semicircular fastening hole is formed in one side of each bolt pin groove, and dumbbell bolt pins matched with the bolt pin grooves are arranged in the bolt pin grooves. Fastening pins are inserted into the fastening holes to lock the dumbbell bolt pins. The joint has the beneficial effects that vertical socket and spigot joint of a common mechanical joint is converted into horizontal pin joint, point connection of line connection and vertical pin joint of a welding joint is converted into face connection, and the joint is easy to manufacture, uniform in stress and higher in bearing capacity.

Description

Technical Field

[0001] The invention relates to the technical field of pile foundation engineering, and in particular to a dumbbell pin pipe pile joint and a design method thereof. Background Art

[0002] Prestressed concrete pipe piles are usually connected by welding and mechanical joints. Welding is the most commonly used method, but defects in weld quality will affect the bearing capacity of the pile. The weld between the two end plates of the pipe pile joint is a circular linear contact with a small contact area. The bearing capacity of the joint is generally lower than that of the pile body. In addition, the uneven thickness of the weld also affects the verticality of the pipe pile. The welding joint takes up a lot of man-hours for piling. It takes 30 to 60 minutes to construct and cool a joint weld. There are many ways to connect mechanical joints. The commonly used mechanical joints are mostly designed in a vertical insertion principle, with racks or convex heads for vertical connection and horizontal spring clamping. The disadvantage of the commonly used vertical insertion mechanical joint is that when the upper and lower sections of the pipe pile are connected, all the pins need to be aligned, which takes a long time. In addition, because of the use of socket and spigot and spring clamping, when subjected to vertical pullout and lateral bending moment, the joint produces a certain amount of opening displacement, which reduces the bearing capacity of the joint and affects the durability of the joint. How to simplify the manufacturing process of pipe piles, facilitate pile connection during on-site construction, and ensure that the bearing capacity of pipe pile joints is not lower than the strength of the pile body is the key technical problem that needs to be solved at present. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a dumbbell pin pipe pile joint and a design method thereof, which transforms the vertical socket connection of the commonly used mechanical joint into a horizontal driven pin connection, and transforms the line connection of the welded joint and the point connection of the vertical pin connection into a surface connection. The joint is simple to manufacture, has uniform force, and has a higher bearing capacity.

[0004] The purpose of the present invention is achieved through the following technical solutions: A dumbbell pin pipe pile joint comprises an upper pipe pile, a lower pipe pile, an upper end plate, a lower end plate and a dumbbell pin, wherein the upper end plate is arranged at the end of the upper pipe pile, the lower end plate is arranged at the end of the lower pipe pile, the upper pipe pile and the lower pipe pile are butted together through the upper end plate and the lower end plate, a plurality of evenly distributed prestressed tendon anchor holes are opened on the upper end plate and the lower end plate along the circumference, an opening is arranged between two adjacent prestressed tendon anchor holes on the upper end plate and the lower end plate, the opening extends from the outer circumference of the end plate to the center of the end plate along the radial direction of the end plate, and the upper end plate and the lower end plate are opposite to each other. A cover plate is provided at each opening, the cover plate closes the opening to form a T-shaped groove, the T-shaped groove on the upper end plate corresponds to the T-shaped groove on the lower end plate one by one, the corresponding two T-shaped grooves are butted together to form an I-shaped pin groove, one side of the pin groove is located at the junction of the upper end plate (101) and the lower end plate (201) and is provided with a semicircular fastening hole, the fastening hole is formed by butting together two arc grooves respectively provided on the upper end plate and the lower end plate, an I-shaped dumbbell pin matched with the pin groove is provided in the pin groove, and a fastening pin (4) is driven into the fastening hole to lock the dumbbell pin (3).

[0005] Furthermore, the cross section of the opening is T-shaped, the cross section of the cover plate is rectangular, and the bottom surface of the cover plate is welded to the surface of the end plate.

[0006] Furthermore, the cross section of the opening is rectangular, the cross section of the cover plate is inverted U-shape, and the inner space of the cover plate and the opening form a T-shaped groove.

[0007] Furthermore, the dumbbell pin gradually tapers from the outer end to the inner end and forms a taper of 1° to 3° along the length direction. The inner end of the dumbbell pin is inserted into the pin groove, and the outer end face of the dumbbell pin is a cylindrical surface that matches the outer wall of the pipe pile.

[0008] Furthermore, based on the above dumbbell pin-bolt pipe-pile joint, the present invention also provides a design method of a dumbbell pin-bolt pipe-pile joint, comprising: When prefabricating the pipe pile, the installation position of the wing plate (303) of the dumbbell pin (3) is determined according to the thickness of the end plate, and then an opening and an arc groove are cut on the end plate, and a cover plate (102) is welded at the opening to form a T-shaped groove; Align the upper end plate (101) and the lower end plate (201), and butt the upper section pipe pile (1) and the lower section pipe pile (2), so that the T-slots on the upper end plate (101) and the lower end plate (201) are butt-jointed to form a pin groove (301), and the arc grooves on the upper end plate (101) and the lower end plate (201) are butt-jointed to form a fastening hole (401); The dumbbell pin (3) is driven into the pin groove (301), and then the fastening pin (4) is driven into the fastening hole (401), so that the fastening pin (4) locks the dumbbell pin (3); Design and verify the bearing capacity of pipe pile joints.

[0009] Furthermore, when the thickness of the end plate is greater than 20 mm, an opening with a T-shaped cross-section is cut out of the end plate at the designed position of the pin groove, and then a cover plate with a rectangular cross-section is welded at the opening, so that after the dumbbell pin is driven in, the wing plate of the dumbbell pin is flush with the end plate surface; when the thickness of the end plate is less than 20 mm, an opening with a rectangular cross-section is cut out of the end plate at the designed position of the pin groove, and then a cover plate with an inverted U-shaped cross-section is welded at the opening, so that after the dumbbell pin is driven in, the wing plate of the dumbbell pin is placed on the end plate.

[0010] Furthermore, the length of the dumbbell pin (3) is 2 / 3 to 3 / 4 of the width of the end plate.

[0011] Furthermore, the design and bearing capacity verification of the pipe pile joints include: Design value of tensile load of dumbbell pin under pull-out load of pipe pile foundation , where is the design value of the pull-out load of the pipe pile foundation, in kN; is the friction resistance of the pile side wall, unit is kN / m 2 , is the length of the pile section, in m; is the radius of the pile, in m, is the number of dumbbell pins at the pipe pile joint; Design value of shear load on dumbbell pin of pipe pile foundation under horizontal load , where is the design value of the horizontal load of the pile foundation, in kN; and are the top and bottom earth pressures of the i-th layer of soil on the active side of the pile ( ), unit kN / m 2 ; is the thickness of the i-th soil layer, in m; n is the number of soil layers that the horizontal load passes through to the pipe pile joint; Under the action of bending moment load, due to the linear distribution of stress at the pipe pile joint, there is a relationship , then the tensile load design value of the dumbbell pin with the largest tensile force is , where is the design value of the bending moment load of the pipe pile joint, in kN▪m; The first Design value of tensile load of dumbbell pin ( ), unit kN, The first The distance from the dumbbell pin to the neutral axis, in m, The distance between the dumbbell pin farthest from the neutral axis and the neutral axis, in meters; Design value of web tensile bearing capacity of dumbbell pin , + , where is the tensile yield strength of the dumbbell pin material, in kN / m 2 ; is the web width of the dumbbell pin, in m; is the length of the dumbbell pin, in m; Design value of web shear capacity of dumbbell pin , , where is the shear yield strength of the dumbbell pin material, in kN / m 2 ; Design value of shear bearing capacity of flange of dumbbell pin , , where is the wing height of the dumbbell pin, in m; Design value of the compressive bearing capacity of the wing plate of the dumbbell pin , , where is the compressive yield strength of the dumbbell pin material, in kN / m 2 ; is the wing width of the dumbbell pin, in m; Design value of shear bearing capacity of pin slot , , where is the web height of the dumbbell pin, in m; Design value of compressive bearing capacity of pin groove , .

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. When the upper and lower sections of the pipe pile are butt-jointed, it is only necessary to align the half-open T-slot of the upper end plate with the half-open T-slot of the lower end plate to form an I-shaped closed dumbbell pin groove, which is less difficult to butt-join than the traditional mechanical vertical connection.

[0013] 2. The present invention completes a pipe pile joint by driving a dumbbell pin horizontally around the end plate of the pipe pile joint, inserting a fastening pin, and tightening it with a hammer. This saves time and has a faster joint speed than the vertical socket method.

[0014] 3. The present invention transforms the line connection of the welding joint and the point connection of the traditional mechanical connection into an I-shaped surface connection. The joint is easy to manufacture, has uniform force and high bearing capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the connection between the upper pipe pile and the lower pipe pile in the present invention; Figure 2 It is a schematic diagram of the structural projection of the upper end plate in the present invention; Figure 3 The installation diagram of the dumbbell pin in the present invention is shown in FIG. Figure 1 ; Figure 4 The installation diagram of the dumbbell pin in the present invention is shown in FIG. Figure 2 ; Figure 5 for Figure 3 A schematic cross-sectional view of the invention, wherein the fastening pin is removed; Figure 6 for Figure 4 A schematic cross-sectional view of the invention, wherein the fastening pin is removed; Figure 7 It is a schematic diagram of the three-dimensional structure of the dumbbell pin in the present invention; Figure 8 It is a schematic diagram of the pull-out force of the dumbbell pin pipe pile joint in the present invention; Fig. 9 It is a schematic diagram of the shear force of the dumbbell pin pipe pile joint in the present invention; Fig.10 It is a schematic diagram of the bending resistance of the dumbbell pin pipe pile joint in the present invention.

[0016] In the figure: 1. upper section of pipe pile; 101. upper end plate; 102. cover plate; 103. weld; 2. lower section of pipe pile; 201. lower end plate; 3. dumbbell pin; 301. pin groove; 302. web plate; 303. wing plate; 4. fastening pin; 401. fastening hole; 5. prestressed tendon anchor hole. DETAILED DESCRIPTION

[0017] The present invention is further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following description.

[0018] When pipe piles are connected, the two butted pipe piles are divided into an upper pipe pile 1 and a lower pipe pile 2, and the upper and lower pipe piles are butted through the end plates at the ends of the pile bodies, and the two butted end plates are divided into an upper end plate 101 and a lower end plate 201, wherein the upper end plate 101 is fixed to the end of the upper pipe pile 1, and the lower end plate 201 is fixed to the end of the lower pipe pile 2.

[0019] like Figure 1-Figure 7As shown, a dumbbell pin pipe pile joint comprises an upper pipe pile 1, a lower pipe pile 2, an upper end plate 101, a lower end plate 201 and a dumbbell pin 3. The upper pipe pile 1 and the lower pipe pile 2 are butted together through the upper end plate 101 and the lower end plate 201. A plurality of evenly distributed prestressed tendon anchor holes 5 are provided on the upper end plate 101 and the lower end plate 201 along the circumference. When the pipe pile is prefabricated, the prestressed tendons inside the pipe pile are anchored to the end plate through the prestressed tendon anchor holes 5, thereby fixing the end plate to the end of the pipe pile. An opening is provided between two adjacent prestressed tendon anchor holes 5 on the upper end plate 101 and the lower end plate 201, and the opening extends from the outer peripheral surface of the end plate to the center of the end plate along the radial direction of the end plate. Cover plates 102 are welded at the openings on the opposite surfaces of the upper end plate 101 and the lower end plate 201 to form welds 103, and the openings are closed by the cover plates 102 to form T-slots, and the T-slots on the upper end plate 101 correspond to the T-slots on the lower end plate 201 one by one. When connecting piles, the corresponding two T-slots are butted together to form an I-shaped pin groove 301. An arc groove is provided on the upper end plate 101 and the lower end plate 201 on one side of the pin groove 301 along the length direction of the pin groove 301. When connecting piles, the two arc grooves are butted together at the junction of the upper end plate 101 and the lower end plate 201 to form a semicircular fastening hole 401. After the upper section pipe pile 1 and the lower section pipe pile 2 are butted together, an I-shaped dumbbell pin 3 that matches the pin groove 301 is driven into the pin groove 301, and then the fastening pin 4 is driven into the fastening hole 401 to lock the dumbbell pin 3, thereby completing the pile connection.

[0020] like Figure 3 , Figure 5 As shown, the cross section of the opening may be T-shaped, and the cross section of the cover plate 102 is correspondingly rectangular. The bottom surface of the cover plate 102 is welded to the surface of the end plate. After the cover plate 102 is welded to the upper end plate 101 and the lower end plate 201, the cover plate 102 closes the opening to form a T-shaped groove.

[0021] like Figure 4 , Figure 6 As shown, the cross section of the opening may also be rectangular, and the cross section of the cover plate 102 is correspondingly inverted U-shaped. After the cover plate 102 is welded on the upper end plate 101 and the lower end plate 201, the inner space of the cover plate 102 and the opening form a T-shaped groove.

[0022] like Figure 7 As shown, the dumbbell pin 3 is welded by a web 302 and a wing plate 303. In order to facilitate the insertion of the dumbbell pin 3 into the pin groove 301, the outer end of the dumbbell pin 3 gradually tapers from thick to inner end and forms a taper of 1° to 3° along the length direction. When the dumbbell pin 3 is inserted, the inner end of the dumbbell pin 3 is inserted inwardly into the pin groove 301, and the outer end face of the dumbbell pin 3 is a cylindrical surface adapted to the outer wall of the pipe pile.

[0023] A design method for the dumbbell pin pipe pile joint includes: (1) When prefabricating the pipe pile, the installation position of the wing plate 303 of the dumbbell pin 3 is determined according to the thickness of the end plate, and then an opening and an arc groove are cut on the end plate, and a cover plate 102 is welded at the opening to form a T-slot.

[0024] Specifically, Figure 3 , Figure 5 As shown, when the thickness of the end plate is greater than 20 mm, an opening with a T-shaped cross section is cut out of the end plate at the designed position of the pin groove 301, and then a cover plate 102 with a rectangular cross section is welded at the opening, so that after the dumbbell pin 3 is driven in, the wing plate 303 of the dumbbell pin 3 is flush with the end plate surface; Figure 4 , Figure 6 As shown, when the thickness of the end plate is less than 20 mm, an opening with a rectangular cross section is cut out of the end plate at the design position of the pin groove 301, and then a cover plate 102 with an inverted U-shaped cross section is welded at the opening, so that after the dumbbell pin 3 is driven in, the wing plate 303 of the dumbbell pin 3 is placed on the end plate. In this embodiment, the thickness of the cover plate 102 is not less than 1 / 2 of the thickness of the end plate, the width of the cover plate 102 is the width of the pin groove 301 + 2 times the thickness of the cover plate 102, and the length of the cover plate 102 is equal to the length of the dumbbell pin 3.

[0025] (2) Align the upper end plate 101 and the lower end plate 201, and butt the upper section pipe pile 1 and the lower section pipe pile 2, so that the T-slots on the upper end plate 101 and the lower end plate 201 are butted to form a pin groove 301 (with a taper of 1° to 3°), and the arc grooves on the upper end plate 101 and the lower end plate 201 are butted to form a fastening hole 401. In this embodiment, the depth of the pin groove 301 and the fastening hole 401 are both 1 / 2 to 2 / 3 of the width of the end plate, and the number of the pin groove 301 and the fastening hole 401 are equal to the number of prestressed tendons in the pipe pile.

[0026] (3) The dumbbell pin 3 is driven into the pin groove 301, and then the fastening pin 4 is driven into the fastening hole 401, so that the fastening pin 4 locks the dumbbell pin 3. In this embodiment, the length of the dumbbell pin 3 is 2 / 3 to 3 / 4 of the width of the end plate, the thickness of the wing plate 303 of the dumbbell pin 3 is not less than 1 / 2 of the thickness of the end plate, and the thickness of the web 302 of the dumbbell pin 3 is not less than 1.5 times the thickness of the end plate. The installation error of the dumbbell pin 3 is determined by strength calculation to be less than 0.5 mm; the diameter of the fastening pin 4 is not less than 1 / 2 of the thickness of the end plate, and the diameter of the fastening hole 401 is slightly larger than the diameter of the fastening pin 4.

[0027] (4) Design and verify the bearing capacity of the pipe pile joints. Figure 7-Figure 10 As shown in the figure, the design and bearing capacity verification of pipe pile joints include: like Figure 8 As shown in the figure, the design value of the tensile load of the dumbbell pin 3 under the pull-out load of the pipe pile foundation is , where is the design value of the pull-out load of the pipe pile foundation, in kN; is the friction resistance of the pile side wall, unit is kN / m 2 , is the length of the pile section, in m; is the radius of the pile, in m, It is the number of dumbbell pins 3 at the pipe pile joint.

[0028] like Fig. 9 As shown in the figure, under the horizontal load, the dumbbell pin 3 is subjected to the shear load design value , where is the design value of the horizontal load of the pile foundation, in kN; and are the top and bottom earth pressures of the i-th layer of soil on the active side of the pile ( ), unit kN / m 2 ; is the thickness of the i-th soil layer, in m; n is the number of soil layers that the horizontal load passes through to the pipe pile joint.

[0029] like Fig.10 As shown in the figure, under the action of bending moment load, due to the linear distribution of stress at the pipe pile joint, there is a relationship , then the tensile load design value of the dumbbell pin 3 with the largest tensile force is , where is the design value of the bending moment load of the pipe pile joint, in kN▪m; The first Design value of tensile load for dumbbell pin 3 ( ), unit kN, The first The distance from the dumbbell pin 3 to the neutral axis, in m, It is the distance between the dumbbell pin 3 farthest from the neutral axis and the neutral axis, in m.

[0030] Design value of tensile bearing capacity of web 302 of dumbbell pin 3 , + , where is the tensile yield strength of the material of the dumbbell pin 3, in kN / m 2 ; is the width of the web 302 of the dumbbell pin 3, in m; is the length of the dumbbell pin 3, in m.

[0031] Design value of shear bearing capacity of web 302 of dumbbell pin 3 , , where is the shear yield strength of the material of the dumbbell pin 3, in kN / m 2 .

[0032] Design value of shear bearing capacity of wing plate 303 of dumbbell pin 3 , , where is the height of the wing plate 303 of the dumbbell pin 3, in m.

[0033] Design value of compressive bearing capacity of wing plate 303 of dumbbell pin 3 , , where is the compressive yield strength of the material of the dumbbell pin 3, in kN / m 2 ; is the width of the wing plate 303 of the dumbbell pin 3, in m.

[0034] Design value of shear bearing capacity of pin slot 301 , , where is the height of the web 302 of the dumbbell pin 3, in m.

[0035] Design value of compressive bearing capacity of pin groove 301 , .

[0036] Based on the above dumbbell pin pipe pile joint and its corresponding design method, when the pile connection operation is carried out at the construction site, a section of pipe pile is driven in first. When the top surface of the pipe pile is about 1.0m above the ground, the driving is stopped, and then another section of pipe pile is hoisted by a crane. When the T-slots on the two sections of pipe pile are all aligned, the dumbbell pin is driven into each pin groove 301, and then the fastening pin 4 is driven into the fastening hole 401 to lock the dumbbell pin 3. During the pile connection process, it is only necessary to align the T-slot on the upper end plate 101 with the T-slot on the lower end plate 201 to form an I-shaped pin groove 301, and then the dumbbell pin 3 is driven into the pin groove 301 from the outer peripheral surface of the end plate along the radial direction of the end plate toward the center of the end plate. Compared with the traditional mechanical vertical connection, the docking difficulty is small and the docking speed is faster; the entire joint is simple to manufacture, and the line connection of the welded joint and the point connection of the traditional mechanical connection are changed to an I-shaped surface connection, so that the joint is evenly stressed and has a high bearing capacity.

[0037] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A dumbbell pin pipe pile joint, characterized in that: The invention comprises an upper pipe pile (1), a lower pipe pile (2), an upper end plate (101), a lower end plate (201) and a dumbbell pin (3), wherein the upper end plate (101) is arranged at the end of the upper pipe pile (1), and the lower end plate (201) is arranged at the end of the lower pipe pile (2), the upper pipe pile (1) and the lower pipe pile (2) are butt-jointed via the upper end plate (101) and the lower end plate (201), a plurality of evenly distributed prestressed tendon anchor holes (5) are provided on the upper end plate (101) and the lower end plate (201) along the circumference, an opening is provided between two adjacent prestressed tendon anchor holes (5) on the upper end plate (101) and the lower end plate (201), the opening extending from the outer circumferential surface of the end plate along the radial direction of the end plate to the center of the end plate, and the upper end plate (101) and the lower end plate (201) are opposite to each other. A cover plate (102) is provided at each opening on the plate surface, and the cover plate (102) closes the opening to form a T-shaped groove. The T-shaped groove on the upper end plate (101) corresponds to the T-shaped groove on the lower end plate (201) one by one, and the two corresponding T-shaped grooves are butted together to form an I-shaped pin bolt groove (301). A semicircular fastening hole (401) is provided at one side of the pin bolt groove (301) at the junction of the upper end plate (101) and the lower end plate (201). The fastening hole (401) is formed by butting together two arc grooves respectively provided on the upper end plate (101) and the lower end plate (201). An I-shaped dumbbell pin bolt (3) adapted to the pin bolt groove (301) is provided in the pin bolt groove (301), and a fastening pin (4) is driven into the fastening hole (401) to lock the dumbbell pin bolt (3).

2. The dumbbell pin pipe pile joint according to claim 1, characterized in that: The cross section of the opening is T-shaped, the cross section of the cover plate (102) is rectangular, and the bottom surface of the cover plate (102) is welded to the surface of the end plate.

3. The dumbbell pin pipe pile joint according to claim 1, characterized in that: The cross section of the opening is rectangular, the cross section of the cover plate (102) is in an inverted U shape, and the inner space of the cover plate (102) and the opening form a T-shaped groove.

4. The dumbbell pin pipe pile joint according to claim 1, characterized in that: The dumbbell pin (3) gradually tapers from the outer end to the inner end and forms a taper of 1° to 3° along the length direction. The inner end of the dumbbell pin (3) is inserted into the pin groove (301). The outer end face of the dumbbell pin (3) is a cylindrical surface adapted to the outer wall of the pipe pile.

5. A design method for a dumbbell pin pipe pile joint as claimed in claim 2 or 3, characterized in that: include: When prefabricating the pipe pile, the installation position of the wing plate (303) of the dumbbell pin (3) is determined according to the thickness of the end plate, and then an opening and an arc groove are cut on the end plate, and a cover plate (102) is welded at the opening to form a T-shaped groove; Align the upper end plate (101) and the lower end plate (201), and butt the upper section pipe pile (1) and the lower section pipe pile (2), so that the T-slots on the upper end plate (101) and the lower end plate (201) are butt-jointed to form a pin groove (301), and the arc grooves on the upper end plate (101) and the lower end plate (201) are butt-jointed to form a fastening hole (401); The dumbbell pin (3) is driven into the pin groove (301), and then the fastening pin (4) is driven into the fastening hole (401), so that the fastening pin (4) locks the dumbbell pin (3); Design and verify the bearing capacity of pipe pile joints.

6. The design method of the dumbbell pin pipe pile joint according to claim 5 is characterized in that: When the thickness of the end plate is greater than 20 mm, an opening with a T-shaped cross section is cut out of the end plate at the designed position of the pin groove (301), and then a cover plate (102) with a rectangular cross section is welded at the opening, so that after the dumbbell pin (3) is driven in, the wing plate (303) of the dumbbell pin (3) is flush with the end plate surface; when the thickness of the end plate is less than 20 mm, an opening with a rectangular cross section is cut out of the end plate at the designed position of the pin groove (301), and then a cover plate (102) with an inverted U-shaped cross section is welded at the opening, so that after the dumbbell pin (3) is driven in, the wing plate (303) of the dumbbell pin (3) is placed on the end plate.

7. The design method of the dumbbell pin pipe pile joint according to claim 5 is characterized in that: The design and bearing capacity verification of pipe pile joints include: The design value of the tensile load of the dumbbell pin (3) under the pull-out load of the pipe pile foundation , where is the design value of the pull-out load of the pipe pile foundation, in kN; is the friction resistance of the pile side wall, unit is kN / m 2 , is the length of the pile section, in m; is the radius of the pile, in m, is the number of dumbbell pins (3) at the pipe pile joint; Under the action of horizontal load, the shear load design value of dumbbell pin (3) is , where is the design value of the horizontal load of the pile foundation, in kN; and are the top and bottom earth pressures of the i-th layer of soil on the active side of the pile ( ), unit kN / m 2 ; is the thickness of the i-th soil layer, in m; n is the number of soil layers that the horizontal load passes through to the pipe pile joint; Under the action of bending moment load, due to the linear distribution of stress at the pipe pile joint, there is a relationship , then the tensile load design value of the dumbbell pin (3) with the largest tensile force is , where is the design value of the bending moment load of the pipe pile joint, in kN▪m; The first The design value of the tensile load of the dumbbell pin (3) ), unit kN, The first The distance from the dumbbell pin (3) to the neutral axis, in m, is the distance between the dumbbell pin (3) farthest from the neutral axis and the neutral axis, in meters; Design value of tensile bearing capacity of web (302) of dumbbell pin (3) , + , where is the tensile yield strength of the material of the dumbbell pin (3), in kN / m 2 ; is the width of the web (302) of the dumbbell pin (3), in m; is the length of the dumbbell pin (3), in m; Design value of shear bearing capacity of web (302) of dumbbell pin (3) , , where is the shear yield strength of the dumbbell pin (3), in kN / m 2 ; Design value of shear bearing capacity of flange (303) of dumbbell pin (3) , , where is the height of the wing plate (303) of the dumbbell pin (3), in m; Design value of compressive bearing capacity of the flange (303) of the dumbbell pin (3) , , where is the compressive yield strength of the material of the dumbbell pin (3), in kN / m 2 ; is the width of the wing plate (303) of the dumbbell pin (3), in m; Design value of shear bearing capacity of pin groove (301) , , where is the height of the web (302) of the dumbbell pin (3), in m; Design value of compressive bearing capacity of pin groove (301) , .

Images