A shear key device and method for the shear resistance of the disk body of an extrusion-expanded branch and plate pile

Abstract

The present invention provides a shear key device and method for shear resistance of the disk body of an extrusion-expanded branch and plate pile, including a first shear platform, a second shear platform and a plurality of steel plate assemblies; the top surface of the first shear platform is coaxial and opposite to the top surface of the second shear platform; the steel plate assembly is a structural member with hinge points provided at both ends and in the middle, one end of the steel plate assembly is hinged to the bottom surface of the first shear platform, and the other end of the steel plate assembly is hinged to the bottom surface of the second shear platform; by arranging shear keys on the disk body of the extrusion-expanded branch and plate pile, a rigid skeleton of the disk body concrete can be formed to jointly resist the vertical shear force and avoid the shear failure of the disk body; at the same time, the improvement of the shear bearing capacity can further increase the disk ring width and disk height, improve the disk end force and the bearing capacity of the pile foundation, reduce the pile length, and achieve the purposes of safety and reliability, building material saving, cost saving, low carbon and environmental protection.

Description

Technical Field

[0001] The present invention belongs to the technical field of infrastructure construction, and particularly relates to a shear key device and method for the shear resistance of the disk body of an extrusion-expanded branch disk pile. Background Technique

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] The extrusion-expanded branch disk pile technology mainly increases the radial dimension of the original straight-hole pile at certain intervals through processes such as extrusion and rotary expansion to form an enlarged disk body, and realizes the increase of the pile foundation bearing capacity by increasing the disk end resistance, thereby shortening the pile length, reducing the engineering quantity, and saving resources.

[0004] The bearing capacity of conventional pile foundation design mainly consists of two parts: side friction resistance + pile end resistance, while the bearing capacity of the extrusion-expanded branch disk pile adds a third part on this basis: disk end resistance, that is, it increases the intermediate disk end force. Conventional pile foundations mainly rely on the side friction resistance of the pile to provide bearing capacity, and the pile end resistance only accounts for about 20% of the pile foundation bearing capacity, while the additional disk end assistance of the extrusion-expanded branch disk pile can be increased to more than 60% of the pile foundation bearing capacity;

[0005] With the rapid development of bridge construction technology in recent years, the extrusion-expanded branch disk pile technology has good economic, social and ecological benefits due to factors such as improving the bearing capacity of bridge pile foundations, reducing project costs, reducing construction risks, and reducing the use of mud, and thus has been widely used in bridge pile foundation construction.

[0006] Compared with conventional pile foundations, the extrusion-expanded branch disk pile has one or more disk bodies protruding from the main pile, so there is one or more disk end forces in terms of force, as Figure 5 shown. Therefore, under the same upper load, the extrusion-expanded branch disk pile with the same diameter can greatly reduce the pile length compared with the ordinary pile foundation. However, due to the disk body protruding from the main pile, the conventional pile foundation steel cage cannot enter, and the disk body is currently made of plain concrete structure, resulting in the relative weakness of the disk body to the main pile, and it is easy to be damaged along the shear sliding surface under the vertical force of the main pile. Under the action of the upper vertical load, a shear sliding surface will be formed along the joint surface of the disk body and the main pile as Figure 6 shown, and there is a risk of shear failure for unreasonable expanded disk designs.

[0007] Conventional extrusion-expanded branch disk piles are all solved by restricting structural measures such as disk height, disk ring width and their ratios in the design, and at the same time, the improvement of the disk end force is also restricted.

[0008] Therefore, how to solve the problem of shear failure of the disk body, further increase the disk ring area, enhance the advantage of the disk end force of the extrusion-expanded branch disk pile, effectively shorten the pile length, and avoid the risk of shear failure is a technical problem to be solved. Summary of the Invention

[0009] In order to solve the above problems, the present invention provides a shear key device and method for shear resistance of the disk body of an extrusion-expanded branch disk pile. In order to overcome this drawback, an active search is made to implant shear keys in the disk body, which can further give play to the advantages of the end force of the extrusion-expanded branch disk pile, thereby shortening the pile length, reducing the cost, and fully exerting the application and popularization value of this technology.

[0010] According to some embodiments, the present invention adopts the following technical solutions:

[0011] In a first aspect, the present invention provides a shear key device for shear resistance of the disk body of an extrusion-expanded branch disk pile, including a first shear platform, a second shear platform, and a plurality of steel plate components;

[0012] The top surface of the first shear platform is coaxial and opposite to the top surface of the second shear platform, and there is a set distance between the two surfaces;

[0013] The steel plate component is a structural member with hinge points provided at both ends and in the middle. One end of the steel plate component is hinged to the bottom surface of the first shear platform, and the other end of the steel plate component is hinged to the bottom surface of the second shear platform.

[0014] Further, both the first shear platform and the second shear platform are of a frame structure.

[0015] Further, the top surfaces of the first shear platform and the second shear platform are circular, square, or polygonal.

[0016] Further, the first shear platform includes a bottom annular steel plate, a top annular steel plate, and long strip-shaped steel plates. The bottom annular steel plate is fixedly connected to the top annular steel plate through the long strip-shaped steel plates.

[0017] Further, the size of the bottom annular steel plate is larger than that of the top annular steel plate.

[0018] Further, eight small holes are equidistantly opened in the radial direction of the bottom annular steel plate for the penetration of acoustic logging tubes and ordinary steel bars.

[0019] Further, the second shear platform has the same structure as the first shear platform. The second shear platform also includes a bottom annular steel plate, a top annular steel plate, and square strip-shaped steel plates. The bottom annular steel plate is fixedly connected to the top annular steel plate through the long strip-shaped steel plates.

[0020] Further, the steel plate component includes a first steel plate and a second steel plate. The first steel plate is hinged to the second steel plate. One end of the first steel plate is hinged to the bottom annular steel plate of the first shear platform, and one end of the second steel plate is hinged to the bottom annular steel plate of the second shear platform.

[0021] Further, before implanting the pile body, there is a set distance between the first shear platform and the second shear platform. The steel plate assembly is linear, and the overall cross-section of the shear key device is rectangular;

[0022] After implanting the pile body, the surfaces of the first shear platform and the second shear platform are in contact. The steel plate assembly bends outward around the middle hinge point, making the overall vertical cross-section of the shear key device hexagonal.

[0023] In a second aspect, the present invention provides a construction method for a shear key device for resisting shear of the disk body of an extrusion-expanded branch disk pile as described in the first aspect, including:

[0024] Construct the main reinforcement steel cage by binding. Remove the stirrups at the disk body position, reserve the embedding position for the shear key, and lower the main reinforcement steel cage into place;

[0025] Before implanting the shear key device, place it closely against the inner wall of the main reinforcement steel cage. Pass a number of first steel bars through the perforations in the bottom annular steel plate of the first shear platform, and pass a number of second steel bars through the perforations in the bottom annular steel plate of the second shear platform;

[0026] Lower the shear key device along the inner wall of the main reinforcement steel cage to the disk position. At this time, there is a set distance between the first shear platform and the second shear platform;

[0027] After the shear key device reaches the disk body and is in place, by pulling the first steel bar and the second steel bar up and down, the top annular steel plates of the first shear platform and the second shear platform are brought into contact with each other, and the steel plate assembly opens outward around the middle hinge point;

[0028] Check whether the steel plate assembly of the shear key device is fully opened. After passing the inspection, proceed to the next process until the pile foundation concrete pouring is completed.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] In this application, the top surface of the first shear platform is coaxial and opposite to the top surface of the second shear platform. The steel plate assembly is a structural member with hinge points provided at both ends and in the middle. One end of the steel plate assembly is hinged to the bottom surface of the first shear platform, and the other end of the steel plate assembly is hinged to the bottom surface of the second shear platform. After implanting the pile body, the surfaces of the first shear platform and the second shear platform are in contact. The steel plate assembly bends outward around the middle hinge point, making the overall cross-section of the shear key device hexagonal. By setting shear keys for the disk body of the extrusion-expanded branch disk pile, a rigid skeleton of the disk body concrete can be formed to jointly resist the vertical shear force and avoid the shear failure of the disk body. At the same time, the increase in the shear bearing capacity can further increase the disk ring width and disk height, improve the disk end force and the pile foundation bearing capacity, reduce the pile length, and achieve the purposes of safety and reliability, saving building materials, saving costs, and low carbon environmental protection. By setting shear keys, the popularization and application of the extrusion-expanded branch disk pile technology can be promoted, bringing greater economic and social benefits.

[0031] Advantages of additional aspects of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention.

[0032] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following preferred embodiments are specifically exemplified below, and in conjunction with the accompanying drawings, the detailed description is as follows. Description of the Drawings

[0033] The accompanying drawings forming a part of the specification of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0034] Figure 1 Embedded elevation view of the shear key device for shear resistance of the disk body of the squeezed-expanded branch disk pile of the present invention;

[0035] Figure 2 Embedded plan view of the shear key device for shear resistance of the disk body of the squeezed-expanded branch disk pile of the present invention;

[0036] Figure 3 Schematic diagram of the shear key structure before implantation of the present invention;

[0037] Figure 4 Schematic diagram of the shear key structure after implantation of the present invention;

[0038] Figure 5 Comparison diagram of the force-bearing modes of conventional pile foundations and squeezed-expanded branch disk piles in the prior art;

[0039] Figure 6 Large-scale drawing of the steel bars of the squeezed-expanded branch disk pile in the prior art;

[0040] Wherein: 1, bottom annular steel plate; 2, top annular steel plate; 3, steel plate assembly; 4, strip-shaped steel plate; 5, main reinforcement; 6, stirrup; 7, main pile; 8, disk body; 9, shear key; 101, disk body cast with plain concrete; 102, steel bars; 103, main body cast with reinforced concrete; 104, shear sliding surface; 105, disk height; 106, disk ring width. Detailed Embodiments

[0041] The present invention will be further described below in conjunction with the drawings and embodiments.

[0042] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0043] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0044] Embodiment 1:

[0045] As Figure 1 shown, this embodiment provides a shear key device for the shear resistance of the disk body of an extrusion-expanded branch disk pile, including a first shear platform, a second shear platform, and a plurality of steel plate components;

[0046] The top surface of the first shear platform is coaxial and opposite to the top surface of the second shear platform;

[0047] The steel plate component is a structural member with hinge points provided at both ends and in the middle. One end of the steel plate component is hinged to the bottom surface of the first shear platform, and the other end of the steel plate component is hinged to the bottom surface of the second shear platform.

[0048] Before implanting the pile body, there is a set spacing between the first shear platform and the second shear platform. The steel plate components are in a straight line, and the overall vertical section of the shear key device is rectangular;

[0049] After implanting the pile body, the surfaces of the first shear platform and the second shear platform are in contact. The steel plate components bend outward around the middle hinge point, making the overall vertical section of the shear key device hexagonal.

[0050] Both the first shear platform and the second shear platform are of a frame structure. The top and bottom surfaces of the first shear platform and the second shear platform can adopt circular, square, pentagonal or other polygonal structures. As a preferred embodiment, the top and bottom surfaces of the first shear platform and the second shear platform are both circular, presenting a frustum structure.

[0051] The first shear platform includes a bottom annular steel plate, a top annular steel plate, and long strip-shaped steel plates. The bottom annular steel plate is fixedly connected to the top annular steel plate through the long strip-shaped steel plates.

[0052] The size of the bottom annular steel plate is larger than that of the top annular steel plate. The bottom annular steel plate is provided with eight small holes at equal radial distances. The diameter of the small holes is 1 - 5 cm, for the penetration of acoustic logging tubes and ordinary steel bars.

[0053] As an embodiment, the bottom annular steel plate is 50 cm larger than the top annular steel plate, and the plate width and plate thickness are the same.

[0054] As an implementation manner, the bottom annular steel plate can be sleeved on the inner wall of the main pile steel reinforcement cage, and the diameter of the bottom annular steel plate is smaller than that of the inner wall of the main pile steel reinforcement cage.

[0055] As an implementation manner, the structure of the second shear platform is the same as that of the first shear platform. The second shear platform also includes a bottom annular steel plate, a top annular steel plate and a square bar-shaped steel plate. The bottom annular steel plate is fixedly connected to the top annular steel plate through a long strip-shaped steel plate.

[0056] As an implementation manner, the steel plate assembly includes a first steel plate and a second steel plate. The first steel plate is hinged to the second steel plate. One end of the first steel plate is hinged to the bottom annular steel plate of the first shear platform, and one end of the second steel plate is hinged to the bottom annular steel plate of the second shear platform.

[0057] Specifically, as Figure 1 shown, by inserting shear keys into the main pile steel bars, the shear keys can be opened when reaching the enlarged disk position. After pouring, the shear keys will be embedded into the concrete and act together with the concrete to resist shear force.

[0058] The structure of the shear key is as follows: No. 1 on the upper and lower sides is an annular steel plate. The outer diameter is calculated to be able to be sleeved on the inner wall of the main pile steel reinforcement cage. The plate width is 10 cm, the plate thickness is 1 cm, and 8 small holes with a diameter of 5 cm are equally spaced along the radial direction to ensure that the acoustic logging tube and ordinary steel bars can pass through. No. 2 is also an annular steel plate. The outer diameter of No. 2 is 50 cm smaller than that of No. 1 annular steel plate, and the plate width and plate thickness are the same. No. 3 is a rectangular steel plate with a plate width of 5 cm and a plate thickness of 1 cm. Hinges are provided at both ends and in the middle to ensure rotation. No. 4 is a rectangular steel plate with a plate width of 5 cm and a plate thickness of 1 cm, and is used to fixedly connect No. 1 and No. 2 annular steel plates.

[0059] Embodiment 2

[0060] This embodiment provides a construction method of a shear key device for shear resistance of the disk body of an extrusion-expanded branch pile as described in Embodiment 1, including:

[0061] The main reinforcement steel cage is bound and constructed. The stirrups are removed at the disk body position, the embedding position of the shear key is reserved, and the main reinforcement steel cage is lowered into place;

[0062] Before the shear key device is implanted, it is placed closely against the inner wall of the main reinforcement steel cage. A number of first steel bars are inserted through the hole openings of the bottom annular steel plate of the first shear platform, and a number of second steel bars are inserted through the hole openings of the bottom plate annular steel plate of the second shear platform;

[0063] The shear key device is lowered along the inner wall of the main reinforcement steel cage to the disk position. At this time, there is a set spacing distance between the first shear platform and the second shear platform;

[0064] After the shear key device reaches the disk body and is in place, by pulling the first steel bar and the second steel bar up and down, the top annular steel plate of the first shear platform is attached to the top annular steel plate of the second shear platform, and the steel plate assembly opens outward around the middle hinge point;

[0065] Check whether the steel plate assembly of the shear key device is fully opened. After passing the inspection, proceed to the next process until the pile foundation concrete pouring is completed.

[0066] Specific construction process:

[0067] 1. The main reinforcement steel cage is normally tied and constructed. At the position of the disk body, the stirrups are removed, the embedding position of the shear key is reserved, and the main reinforcement steel cage is normally lowered into place.

[0068] 2. Before implanting the shear key, place it closely against the inner wall of the normal steel cage. Pass steel bars with the same diameter as the main reinforcement bars of the main pile steel cage through the 8 openings of the No. 1 annular steel plate. Among them, four steel bars at intervals are welded to the lower No. 1 annular steel plate, and the other four steel bars are welded to the upper No. 1 annular steel plate.

[0069] 3. Lower the shear key along the inner wall of the steel cage to the disk position. At this time, the upper and lower No. 2 annular steel plates are separated, as shown in Figure 3 ;

[0070] 4. After the shear key reaches the disk body and is in place, by pulling 8 steel bars up and down, among which the 4 steel bars welded to the lower No. 1 annular steel plate are pulled upward, and the 4 steel bars welded to the upper No. 1 annular steel plate are pushed downward until the upper and lower No. 2 steel plates are attached together, as shown in Figure 4 ;

[0071] 5. Check whether the shear key is fully opened. After passing the inspection, proceed to the next process until the pile foundation concrete pouring is completed.

[0072] By setting shear keys on the disk body of the squeezed-expanded branch disk pile, a rigid framework of the disk body concrete can be formed to jointly resist the vertical shear force and avoid the shear failure of the disk body. At the same time, the increase in the shear bearing capacity can further increase the disk ring width and disk height, improve the disk end force and the pile foundation bearing capacity, reduce the pile length, and achieve the purpose of saving building materials, reducing costs, and being low-carbon and environmentally friendly. By setting shear keys, the popularization and application of the squeezed-expanded branch disk pile technology can be promoted, bringing greater economic and social benefits.

[0073] According to Article 9.5.4 of the "Code for Design of Highway Bridge and Culvert Foundations" (JTG 3363-2019), when other parameters remain unchanged, by increasing the disk ring area, that is, A pj , the vertical bearing capacity of the squeezed-expanded branch disk pile can be effectively improved.

[0074] Although the specific implementation manners of the present invention have been described above in conjunction with the accompanying drawings, it is not a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications or deformations that can be made without creative efforts on the basis of the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A shear key device for the shear resistance of the disk body of an extrusion-expanded branch and plate pile, characterized in that, It includes a first shear platform, a second shear platform and a number of steel plate components; The top surface of the first shear platform is coaxial and opposite to the top surface of the second shear platform; The steel plate component is a structural member with hinge points provided at both ends and in the middle. One end of the steel plate component is hinged to the bottom surface of the first shear platform, and the other end of the steel plate component is hinged to the bottom surface of the second shear platform; The first shear platform includes a bottom annular steel plate, a top annular steel plate and strip-shaped steel plates. The bottom annular steel plate is fixedly connected to the top annular steel plate through the strip-shaped steel plates; The second shear platform has the same structure as the first shear platform. The second shear platform also includes a bottom annular steel plate, a top annular steel plate and strip-shaped steel plates. The bottom annular steel plate is fixedly connected to the top annular steel plate through the strip-shaped steel plates.

2. The shear key device for the shear resistance of the disk body of the squeezed-expanded branch and plate pile according to claim 1, characterized in that, Both the first shear platform and the second shear platform are of frame structure.

3. The shear key device for the shear resistance of the disk body of the squeezed-expanded branch disk pile according to claim 1, characterized in that, The top surfaces of the first shear platform and the second shear platform are circular or polygonal.

4. The shear key device for shear resistance of the disk body of the squeezed-expanded branch disk pile according to claim 1, characterized in that, The size of the bottom annular steel plate is larger than that of the top annular steel plate.

5. The shear key device for the shear resistance of the disk body of the squeezed-expanded branch disk pile according to claim 1, characterized in that, Eight holes are equidistantly opened in the radial direction of the bottom annular steel plate for the penetration of sonic logging tubes and ordinary steel bars.

6. The shear key device for shear resistance of the disk body of the squeezed-expanded branch disk pile according to claim 1, characterized in that, The steel plate component includes a first steel plate and a second steel plate. The first steel plate is hinged to the second steel plate. One end of the first steel plate is hinged to the bottom annular steel plate of the first shear platform, and one end of the second steel plate is hinged to the bottom annular steel plate of the second shear platform.

7. The shear key device for the shear resistance of the disk body of the squeezed-expanded branch and plate pile according to claim 1, wherein, Before implanting the pile body, there is a set spacing between the first shear platform and the second shear platform. The steel plate component is in a straight line shape, and the overall vertical section of the shear key device is rectangular; After implanting the pile body, the surfaces of the first shear platform and the second shear platform are in contact. The steel plate component bends outward around the middle hinge point, so that the overall vertical section of the shear key device is hexagonal.

8. A construction method of a shear key device for shear resistance of the disk body of an extrusion-expanded branch and plate pile as described in any one of claims 1-7, characterized in that, It includes: The main reinforcement steel cage is constructed by binding. The stirrups are released at the disk position, the embedding position of the shear key is reserved, and the main reinforcement steel cage is lowered into place; Before implanting the shear key device, it is placed closely against the inner wall of the main reinforcement steel cage. A number of first steel bars are inserted through the openings of the bottom annular steel plate of the first shear platform, and a number of second steel bars are inserted through the openings of the bottom plate annular steel plate of the second shear platform; The shear key device is lowered along the inner wall of the main reinforcement steel cage to the disk position. At this time, there is a set spacing between the first shear platform and the second shear platform; After the shear key device reaches the disk position and is in place, by pulling the first steel bar and the second steel bar up and down, the top annular steel plate of the first shear platform is in contact with the top annular steel plate of the second shear platform, and the steel plate component opens outward around the middle hinge point; Check whether the steel plate component of the shear key device is fully opened. After passing the inspection, the next process is carried out until the pile foundation concrete pouring is completed.

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