Prefabricated concrete polygonal pile and combined pile foundation
By introducing stress buffer surfaces and cylindrical connecting sections into precast concrete polygonal piles, the problems of difficult construction alignment and stress concentration were solved, achieving efficient and stable pile foundation connection and improved bearing capacity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-10
- Publication Date
- 2026-03-10
AI Technical Summary
Existing precast concrete square piles have problems such as difficulty in alignment, waste of materials and time during construction, and stress concentration at the pile end, which affects the bearing capacity and connection quality.
A stress buffer surface is used to transition the polygonal pile segment to the cylindrical connecting segment, increasing the contact area between the pile and the soil and reducing stress concentration. The pile end is adjusted to be circular to facilitate alignment and connection.
It improved construction efficiency, reduced material waste, ensured the vertical bearing capacity of the pile and soil, avoided stress concentration, and improved the quality of the pile body.
Smart Images
Figure CN121629918A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of building engineering technology, and in particular to a precast concrete polygonal pile and a composite pile foundation. Background Technology
[0002] Precast concrete piles possess advantages such as high bearing capacity, stable quality, economic efficiency, good durability, and environmental friendliness, and are widely used in industrial and civil construction, railways, highways, and municipal engineering. With the acceleration of urban construction and the need to meet the engineering requirements of complex and varied geological conditions, the types and shapes of precast concrete piles have diversified, but circular and square outlines remain the most common. Circular precast piles are widely used due to their uniform stress distribution and excellent performance and stability under vertical or horizontal loads; the main pile type is the centrifugal concrete pipe pile. In addition to circular cross-sections, there are also precast piles with square cross-sections, mainly including solid square piles and hollow square piles. When using square piles with the same side length as the pipe pile diameter, the outer perimeter is larger. When constructing friction piles in soft soil areas, the outer side of the pile has a larger contact area with the soil layer, resulting in greater vertical lateral resistance. However, polygonal piles currently face the following problems during construction. Taking square piles as an example: (1) When square piles are driven into the ground for splicing, the two piles need to be aligned. In actual construction, there will be deviations between the upper and lower piles, making it difficult to align them completely; (2) When square piles are connected to the upper concrete foundation, there are standard regulations specifying the minimum distance between the four edges of the square pile and the foundation. If the side of the square pile is not parallel to the concrete foundation, the foundation size needs to be increased to meet the current standard requirements, which consumes materials and time. Figure 1 The diagram shown illustrates normal construction when a square pile is connected to a pile cap, where L3 meets the standard requirements. Figure 2 The diagram in the middle shows the connection between the square pile and the pile cap during abnormal construction. With the pile cap size remaining unchanged, L3 meets the standard requirements, and the pile cap size needs to be increased. Summary of the Invention
[0003] To address the shortcomings of existing technologies, this invention provides a precast concrete polygonal pile. It employs a stress buffer surface to connect the polygonal pile segment with the cylindrical connecting segment. This increases the contact area between the pile and the soil without reducing the vertical bearing capacity of the polygonal pile, reduces stress concentration at the four corners of the polygonal pile, and facilitates construction alignment.
[0004] The present invention achieves the above-mentioned technical objectives through the following technical means.
[0005] A precast concrete polygonal pile has a circular steel reinforcement cage inside the pile body. The pile body includes continuous polygonal pile segments and cylindrical connecting segments at both ends of the polygonal pile segments. The polygonal pile segments and the cylindrical connecting segments are connected by a stress buffer surface. The horizontal angle between the stress buffer surface and the pile cross-section is 45°≤β<90°.
[0006] Preferably, the horizontal angle between the stress buffer surface and the pile cross-section is 45°≤β≤55°.
[0007] Preferably, the cross-section of the cylindrical connecting segment is the incircle of the cross-section of the polygonal pile segment, and the length of the cylindrical connecting segment is L1. <a。
[0008] Preferably, the outer diameter of the cylindrical connecting section is larger than the diameter of the reinforcing cage and smaller than the diameter of the inscribed circle of the polygonal pile segment.
[0009] Preferably, the cylindrical connecting section is provided with a pile sleeve.
[0010] Preferably, the diameter of the steel reinforcement cage is 0.75 to 0.90 times the diameter of the inscribed circle of the polygonal pile segment.
[0011] Preferably, the stress buffer surface is an inverted triangle, the base of which is the tangent of the cylindrical connecting segment or the outline of the cylindrical connecting segment, and the vertex of the triangle corresponding to the base is located on the edge of the polygonal pile segment.
[0012] Preferably, the stress buffer surface is an outwardly arc-shaped convex surface.
[0013] Preferably, there are multiple stress buffer surfaces, which are respectively placed at the corners of the ends where the polygonal pile segment and the cylindrical connecting segment meet.
[0014] Preferably, at least one face of the polygonal pile segment is provided with a grouting groove.
[0015] Preferably, the steel reinforcement cage includes main bars and spiral stirrups. The main bars are grouped in a circular and uniform manner and are usually arranged, with each group of main bars including at least two main bars.
[0016] Preferably, each group of main reinforcement bars is distributed at the corner of the polygonal pile segment.
[0017] A composite pile foundation includes the aforementioned precast concrete polygonal piles, wherein the sides of the upper and lower precast concrete polygonal piles are staggered, and the edges of the upper precast concrete polygonal piles protrude from the side of the corresponding lower precast concrete polygonal piles.
[0018] Preferably, the angle bisector of the upper precast concrete polygonal pile coincides with the centerline on the side of the lower precast concrete pile.
[0019] The present invention has the following beneficial effects:
[0020] (1) This invention has the characteristics of simple structure, high bearing capacity, novel and beautiful shape, and high production efficiency. The performance of the pile body is comparable to that of the existing conventional polygonal piles. The ends of the polygonal piles are adjusted to be circular, which can effectively correct the deviation when splicing the piles. It is only necessary to align the two pile heads, without aligning all the surfaces of the upper and lower piles. When the pile is connected to the pile cap, regardless of whether the pile is tilted (tilt means that the side of the square section of the pile is not parallel to the edge of the pile cap, rather than the pile body tilting relative to the horizontal plane), as long as the center of the pile meets the requirements (the pile is perpendicular to the horizontal plane), the distance from the pile end to the pile cap can meet the requirements.
[0021] (2) The present invention adjusts the polygonal pile end from a polygon to a circle, and then uses a stress buffer surface transition, which effectively releases the stress during the construction process and diffuses it from all four sides to each buffer surface, improving the quality of the precast pile after construction. The reduced contact area between the pile body and the soil at the end is compensated by the stress buffer surface, which increases the contact area between the pile and the soil and ensures the vertical bearing capacity of the pile.
[0022] (3) The present invention adjusts the end of the polygonal pile from a polygon to a circle. When the pile is hammered, the pile end is subjected to more uniform force, which can effectively avoid the stress concentration phenomenon at the pile corner. Attached Figure Description
[0023] Figure 1 This is a schematic diagram illustrating normal construction when a square pile is connected to a pile cap in the background technology.
[0024] Figure 2 This is a schematic diagram of the connection between the square pile and the pile cap during an abnormal construction situation, as shown in the background art.
[0025] Figure 3 This is a schematic diagram of the precast concrete polygonal pile structure of the present invention;
[0026] Figure 4 for Figure 3 A schematic diagram of the steel reinforcement cage layout;
[0027] Figure 5 This is a front view of the precast concrete polygonal pile of the present invention;
[0028] Figure 6 This is a schematic diagram of the precast concrete polygonal pile structure in Example 2;
[0029] Figure 7 This is a schematic diagram of the steel cage arrangement in Example 3;
[0030] Figure 8 This is a schematic diagram of the steel cage arrangement in Example 3;
[0031] Figure 9This is a schematic diagram of the precast concrete polygonal pile in Example 4;
[0032] Figure 10 for Figure 9 A top-down view of the grouting trenches on opposite sides;
[0033] Figure 11 for Figure 9 A top-view diagram showing the installation of grouting grooves on adjacent surfaces;
[0034] Figure 12 for Figure 10 A schematic diagram of the straight-line connection method for precast polygonal concrete piles;
[0035] Figure 13 for Figure 11 A schematic diagram of the corner connection method for precast polygonal concrete piles;
[0036] Figure 14 This is a schematic diagram of a composite pile foundation.
[0037] Figure 15 for Figure 14 Top view.
[0038] Figure label:
[0039] 1-Polygonal pile segment; 1-1-Grouting groove; 2-Cylindrical connecting section; 3-Reinforcing steel cage; 3-1-Main reinforcement; 3-2-Helical stirrup; 4-Stress buffer surface; 4-1 Upper outline; 4-2-Lower outline; 5-Pile sleeve; 6-Sealing material; 7-Upper precast concrete square pile; 8-Lower precast concrete square pile; 9-Pile cap; 10-Square pile. Detailed Implementation
[0040] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.
[0041] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.
[0042] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0043] Example 1
[0044] Combined with appendix Figure 3 and 4 As shown, a precast concrete polygonal pile has a circular steel reinforcement cage 3 inside the pile body. The pile body includes a polygonal pile segment 1 and cylindrical connecting segments 2 located at both ends of the polygonal pile segment 1. The polygonal pile segment 1 and the cylindrical connecting segments 2 are connected by a stress buffer surface 3. The cross-section of the cylindrical connecting segment 2 is slightly smaller than the inscribed circle of the cross-section of the polygonal pile segment 1. A pile sleeve 5 is provided on the cylindrical connecting segment 2. Figure 5 As shown, the horizontal angle between the stress buffer surface 3 and the pile cross-section is 45°≤β<90°. Within this angle range, the length of the stress buffer surface is... (In the formula, a is the side length of the polygonal pile segment,) so that the pile experiences less pile driving resistance during the pile driving process and less disturbance to the soil.
[0045] by
[0046] The length L1 of the cylindrical connecting section is less than a, because the cylindrical connecting section is used for connecting the upper and lower precast piles and plays a role in connecting the preceding with the following. When the length of the cylindrical connecting section is too long, it is equivalent to shrinking the polygon into an inscribed circle, reducing the side resistance of the polygonal pile. Controlling the length of the cylindrical connecting section within the range of 1 times the side length can effectively control the loss of the bearing capacity of the original polygonal pile. The cylindrical connecting section 2 is located at the end of the polygonal pile section. From the cross-section, the cylindrical connecting section is tangent to the polygonal pile section, increasing the contact area between the pile and the soil without changing the vertical bearing capacity of the pile, facilitating pile connection alignment and controlling the area of the pile and the bearing platform.
[0047] When 45° ≤ β ≤ 55°, the length of the stress buffer surface The length L2 within this range can effectively reduce the loss of side resistance at the cylindrical connecting section.
[0048] As Figure 3 shown, when the polygonal pile section is a square pile, there are 4 stress buffer surfaces, which are respectively placed at the corners of one end where the polygonal pile section and the cylindrical connecting section are connected. The stress buffer surface 4 is an inverted triangle, including an upper contour line 4-1 and a lower contour line 4-2. The upper contour line 4-1 is the contour line of the cylindrical connecting section corresponding to the corner of the square pile, and the lower contour line 4-2 is set on two adjacent side surfaces of the square pile section 1. The lower contour line 4-2 is a convex arc. The stress buffer surface enclosed by the upper contour line 4-1 and the lower contour line 4-2 is an outwardly convex arc surface, increasing the contact area between the pile and the soil mass, thereby increasing the friction force and uplift resistance.
[0049] As Figure 4 shown, the steel reinforcement cage 3 includes uniformly distributed main reinforcements 3-1 and spiral stirrups 3-2, and the main reinforcements 3-1 are arranged along the entire pile length. The diameter of the cylindrical connecting section 2 is larger than the diameter of the steel reinforcement cage 3 and smaller than the diameter of the inscribed circle of the pile section of the polygonal pile section; the main reinforcements 3-1 are arranged along the entire pile length to achieve full-length tensioning, with better force. If the diameter of the cylindrical connecting section 2 is smaller than the diameter of the steel reinforcement cage 3, it will cause the cylindrical connecting section to be unable to achieve prestress tensioning (similar to the pile tip of a pencil pile without prestress), affecting the overall mechanical properties of the pile body.
[0050] Preferably, the diameter of the steel reinforcement cage 3 is 0.75 - 0.90 times the diameter of the inscribed circle of the cross-section of the polygonal pile section. If the diameter of the steel reinforcement cage is too large, the concrete cover thickness of the steel bars will not meet the anti-corrosion requirements. If the diameter of the steel reinforcement cage is too small, it is not conducive to the restraint of the concrete at the corners of the polygonal pile.
[0051] Example 2
[0052] As Figure 6As shown, in this embodiment, the stress buffer surface 4 includes an upper contour line 4-1 and a lower contour line 4-2. The upper contour line is the tangent to the contour line of the cylindrical connecting segment corresponding to the corner of the polygonal segment. The lower contour line 4-2 is set on two adjacent sides of the polygonal pile segment 1. The projection of the contour line of the square pile end body between the upper contour line 4-1 and the two adjacent upper contour lines 4-1 on the horizontal plane is an octagonal shape. The cylindrical connecting segment is the inscribed circle of the octagon, ensuring that the stress received during hammering is evenly distributed on each surface. Other structures are the same as in Embodiment 1.
[0053] Example 3
[0054] When there are many reinforcement bars, if the main reinforcement bars 3-1 are still arranged evenly as usual, the aggregate in the concrete will not be able to pass through the steel reinforcement cage, thus affecting the final strength of the pile concrete; combined with the attached... Figure 7 As shown, the steel reinforcement cage 3 includes main bars 3-1 and spiral stirrups 3-2. The main bars 3-1 are arranged in uniform circular groups, with increased spacing between adjacent groups to facilitate the passage of stones; as shown... Figure 8 As shown, each group of main reinforcement bars is distributed at the corners of the polygonal pile segment. This arrangement structure not only avoids the problem that the stones in the concrete cannot pass through the reinforcement cage due to excessively dense reinforcement, thus affecting the final strength of the pile concrete, but also increases the concrete stress at the four corners of the square pile segment, improving the protection of the pile head during hammering construction. Other structures are the same as in Example 1.
[0055] Example 4
[0056] Combined with appendix Figures 9 to 13 As shown, a precast concrete polygonal pile includes a polygonal pile segment 1, two cylindrical connecting segments 2, and a steel reinforcement cage 3. The polygonal pile segment 1 and the cylindrical connecting segments 2 are connected by a stress buffer surface 4. At least one surface of the polygonal pile segment 1 is provided with at least one grouting groove 1-1 (in this embodiment, there are two arc-shaped grouting grooves; the cross-sectional shape of the grouting grooves can also be trapezoidal). When used for support engineering, the grouting grooves 5 can be filled with sealing material 6 after the precast pile is driven, which has the functions of water stoppage and soil retention.
[0057] Combined with appendix Figure 10 and 12 As shown, where, Figure 12 This is a schematic diagram of grouting grooves on opposite faces of a precast concrete polygonal pile. When grouting grooves 5 are provided on opposite faces of two polygonal pile segments 1, they are mainly used for splicing straight segments.
[0058] Combined with appendix Figure 11 and 13 As shown, where, Figure 13This is a schematic diagram of grouting grooves on adjacent surfaces of a precast concrete polygonal pile. When grouting grooves 1-1 are provided on adjacent surfaces of two polygonal pile segments 1, they are mainly used for splicing corner segments. The cross-sections of the polygonal pile segments and the cylindrical connecting segments can also be solid cross-sections. Other structures are the same as in Example 1.
[0059] Example 5
[0060] The sides of the upper and lower precast concrete polygonal piles are staggered, with the edges of the upper precast concrete polygonal pile protruding from the side of the corresponding lower precast concrete polygonal pile.
[0061] Combined with appendix Figure 14 , 15 As shown, taking a square pile as an example, when the end is set to be circular, the cross-sectional direction of the precast concrete square pile can be adjusted to form the combination shown in the figure below (i.e., the lower section of the precast concrete square pile 8 is misaligned with the upper section of the precast concrete square pile 7). After the lower section of the precast concrete square pile 8 is connected to the upper section of the precast concrete square pile 7, the entire pile forms a "convex" shape. When used for pull-out resistance, the square pile is in a state of force from bottom to top. Due to the effect of the protrusion of the lower section of the precast concrete square pile, the final area with the soil on the side of the pile is increased, and more surrounding soil can be moved, thereby obtaining a higher pull-out bearing capacity (i.e., a higher pull-out coefficient).
[0062] The angle bisector of the upper precast concrete polygonal pile coincides with the centerline of the side of the lower precast concrete pile. In this case, the perimeter at the joint of the two piles is the largest, thus maximizing the contact area between the pile and the soil. The protruding part can also receive vertical forces from the soil above, resulting in better pull-out resistance. If both the upper and lower piles are square, the upper pile only needs to be rotated 45° relative to the lower pile. If both the upper and lower piles are triangular, the upper pile only needs to be rotated 60°.
[0063] In the above embodiments, the polygonal pile segment 1 can be a hollow pile segment or a solid pile segment, and the cylindrical connecting segment can be a solid pile segment or a hollow pile segment.
[0064] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0065] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.
Claims
1. A precast concrete polygonal pile, characterized by, The pile body is provided with a circular reinforcement cage, and the pile body comprises continuous polygonal pile section bodies and cylindrical connecting sections arranged at both ends of the polygonal pile section bodies; the polygonal pile section bodies and the cylindrical connecting sections are connected through a stress buffer surface; and the horizontal angle between the stress buffer surface and the cross section of the pile is 45°≤β<90°.
2. A precast concrete polygonal pile according to claim 1, characterised in that, The horizontal angle between the stress buffer surface and the cross section of the pile is 45°≤β≤55°.
3. A precast concrete polygonal pile according to claim 1, characterised in that, The cross section of the cylindrical connecting section is an inscribed circle of the cross section of the polygonal pile section body, and the length L1 of the cylindrical connecting section is less than a.
4. A precast concrete polygonal pile according to claim 1, characterised in that, The outer diameter of the cylindrical connecting section is greater than the diameter of the reinforcement cage and less than the diameter of the inscribed circle of the polygonal pile section body.
5. A precast concrete polygonal pile according to claim 4, characterised in that, The cylindrical connecting section is provided with a pile sleeve.
6. A precast concrete polygonal pile according to claim 4, characterised in that, The diameter of the reinforcement cage is 0.75-0.90 times the diameter of the inscribed circle of the cross section of the polygonal pile section body.
7. A precast concrete polygonal pile according to claim 1, characterised in that, The stress buffer surface is in the shape of an inverted triangle, the base of the triangle is a tangent line of the cylindrical connecting section or a contour line of the cylindrical connecting section, and the vertex of the triangle corresponding to the base is arranged on the edge of the polygonal pile section body.
8. A precast concrete polygonal pile according to claim 6, characterised in that, The stress buffer surface is an outer arc convex surface.
9. A precast concrete polygonal pile according to claim 1, characterised in that, The stress buffer surface is provided with a plurality of stress buffer surfaces, which are arranged at the corner of one end of the polygonal pile section body and the cylindrical connecting section.
10. A precast concrete polygonal pile according to claim 1, characterised in that, At least one surface of the polygonal pile section body is provided with a grouting groove.
11. A precast concrete polygonal pile according to claim 1, characterised in that, The reinforcement cage comprises main reinforcement and spiral stirrups, the main reinforcement is arranged in groups in a circular shape and uniformly and continuously, and each group of main reinforcement comprises at least two main reinforcements.
12. A precast concrete polygonal pile according to claim 11, characterised in that, Each group of main reinforcement is distributed at the corner of the polygonal pile section body.
13. A composite pile foundation comprising a precast concrete polygonal pile according to any one of claims 1-12, characterized in that, The side surfaces of the upper and lower prefabricated concrete polygonal piles are arranged in a staggered manner, and the edges of the upper prefabricated concrete polygonal pile protrude from the side surface of the corresponding lower prefabricated concrete polygonal pile.
14. A composite pile foundation according to claim 13, characterised in that: The angle bisector of the upper prefabricated concrete polygonal pile and the middle line of the edge of the lower prefabricated concrete pile coincide.