Prefabricated screw pile and screw pile mold
By designing precast spiral piles with single spiral grooves and using mold production technology, the problems of pile head cracking and insufficient bearing capacity were solved, and the pile body crack prevention and bearing capacity improvement were achieved during the construction process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI JIACHENG ZHUYOU BUILDING MATERIALS TECHNOLOGY CO LTD
- Filing Date
- 2025-04-23
- Publication Date
- 2026-05-12
AI Technical Summary
Existing precast helical piles are prone to pile head cracking during construction, and their bearing capacity is affected by the soil conditions of the construction site. In particular, the bearing capacity is insufficient in silty soil layers. Traditional methods of increasing friction can easily lead to excessively thick steel reinforcement protective layers or pile body cracking.
A precast helical pile is designed, which adopts a single helical groove structure with a trapezoidal groove cross-section. The pitch and depth are reasonably configured to increase the contact area between the pile and the soil. It is produced by helical pile mold to reduce stress concentration and enhance bearing capacity.
It effectively prevents pile head cracking, increases the friction between the pile and the soil, and improves bearing capacity, especially showing better construction results in silty soil layers.
Smart Images
Figure CN224227776U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of building pile foundation engineering technology, and in particular to a prefabricated helical pile and a helical pile mold. Background Technology
[0002] In recent years, with the acceleration of urbanization and the increasing demand for infrastructure construction, the requirements for bearing capacity, construction efficiency, and environmental protection in pile foundation engineering under complex geological conditions have become increasingly stringent. Traditional cast-in-place piles, mixing piles, and helical piles, which involve on-site wet construction, have an impact on the urban environment. Precast piles have become the main alternative. However, with the development of the industry, the types of precast piles are increasing, from traditional pipe piles and square piles to later irregularly shaped piles. In addition to providing a certain end bearing capacity at the pile tip, precast piles mainly provide the main bearing capacity through the side friction resistance between the pile body and the soil. Currently, irregularly shaped piles such as bamboo-joint piles and helical friction piles have appeared on the market to increase the friction of the pile body.
[0003] However, in existing bamboo-joint piles, the bamboo joints enlarge the hole in the soil, preventing the soil from returning to the necked end in a short time. This leads to decreased friction and settlement, affecting project quality. Furthermore, the excessive protective layer for the reinforcing steel at the bamboo joints makes the pile body prone to cracking. Existing spiral friction piles typically extend spiral grooves to both ends of the pile body. Increasing the number of grooves or grouting them further enhances friction. However, increasing the number of threads also reduces the pile cross-section, causing stress concentration and affecting quality. Deepening and increasing the number of grooves to increase friction also results in an excessively thick protective layer for the reinforcing steel, making the pile body prone to cracking and affecting its service life. During construction, these spiral friction piles are also prone to cracking of the pile head and body due to stress concentration from hammering.
[0004] Whether it is an expanded diameter bamboo joint pile or a necked spiral pile, its bearing capacity depends on the soil quality of the construction site. Since the lower end of the pile needs to be embedded in a good soil layer, the middle soil layer of the pile is relatively poor, especially the silty soil in a fluid plastic state. Therefore, when spiral piles and bamboo joint piles enter a good soil layer, the soil will reduce the bearing capacity because it cannot be replenished. Utility Model Content
[0005] The present invention aims to provide a precast helical pile and a helical pile mold to enhance the bearing capacity of the precast helical pile and prevent the pile head from cracking during construction.
[0006] To achieve the above object, the technical solution of the present utility model is: a precast spiral pile, comprising a pile body; a groove, the groove being a single spiral groove, and the groove spirally distributed on the outer circumferential surface of the pile body; the starting point of the groove is A, the ending point is B, the starting point A is connected to the end surface of one end of the pile body or has a distance from the end surface of one end of the pile body, and the ending point B has a distance from the end surface of the other end of the pile body.
[0007] In a preferred embodiment of the present utility model, the distance from the ending point B to the end surface of the other end of the pile body is set as H2, and 30 cm < H2 ≤ 200 cm.
[0008] In a preferred embodiment of the present utility model, the distance from the starting point A to the end surface of one end of the pile body is set as H1, and 30 cm < H1 ≤ 500 cm.
[0009] In a preferred embodiment of the present utility model, the cross-section of the groove is trapezoidal, and the outer vertical length of the cross-section of the groove is greater than the inner vertical length of the cross-section of the groove.
[0010] In a preferred embodiment of the present utility model, the cross-section of the groove is an isosceles trapezoid, and the depth of the groove is set as l, and 0 < l ≤ 3 cm.
[0011] In a preferred embodiment of the present utility model, the outer vertical length of the cross-section of the groove is set as a, and the inner vertical length is set as b, and 0 < a - b < 4 cm.
[0012] In a preferred embodiment of the present utility model, the pitch m of the groove is equal.
[0013] In a preferred embodiment of the present utility model, the side friction resistance value Q sk of the precast spiral pile has the following formula: The length of the groove of the i-th layer
[0014] In a preferred embodiment of the present utility model, the range of the pitch m is 25 < m < 60 cm.
[0015] In a preferred embodiment of the present utility model, a - b = 2 cm, a = 10 cm, m = 40 cm, and l = 2 cm.
[0016] In a preferred embodiment of the present utility model, the outer area of the groove accounts for 1 / 6 - 1 / 2 of the lateral surface area of the pile body.
[0017] In a preferred embodiment of the present utility model, the inclination angle of the groove is 5° - 60°.
[0018] In a preferred embodiment of this utility model, the ratio of the outer vertical length a of the groove to the net length ma between adjacent threads is 1 / 5-1.
[0019] In a preferred embodiment of the present invention, a through hole is further included, which is coaxially arranged with the pile body and penetrates the pile body.
[0020] In a preferred embodiment of this utility model, the grooves are continuously spiraled and distributed on the outer circumferential surface of the pile body.
[0021] In a preferred embodiment of this utility model, the grooves are intermittently spiraled and distributed on the outer circumferential surface of the pile body.
[0022] In a preferred embodiment of this utility model, the starting point A and the ending point B are located on the same plane.
[0023] This utility model also provides a helical pile mold for producing any of the prefabricated helical piles described above.
[0024] In a preferred embodiment of this utility model, it includes a first module, a second module, a first protrusion, and a second protrusion. The first module and the second module are the same size. The first protrusion and the second protrusion are respectively disposed on the inner side of the first module and the second module. After the first protrusion and the second protrusion are assembled, they are the same as the groove.
[0025] This invention can effectively reduce the occurrence of pile head cracking due to stress concentration during the construction of precast helical piles, increase the contact surface area of precast helical piles, and increase the bearing capacity by deriving and selecting values through reasonable formulas.
[0026] To make the above-mentioned features and advantages of the utility model more apparent and understandable, specific embodiments are described below, and detailed descriptions are provided in conjunction with the accompanying drawings. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the prefabricated spiral pile structure of this utility model.
[0028] Figure 2 This is a schematic diagram of the prefabricated spiral pile of this utility model.
[0029] Figure 3 for Figure 2 A magnified view of section V in the image.
[0030] Figure 4 This is a schematic diagram of the spiral pile mold structure of this utility model.
[0031] Figure 5 This is a schematic diagram of the first module of the spiral pile mold of this utility model.
[0032] Figure 6 This is a schematic diagram of the second module of the spiral pile mold of this utility model.
[0033] 1-Precast spiral pile; 11-Pile body; 12-Through hole; 13-Groove; A-Starting point; B-Ending point; 2-Spiral pile mold; 21-First module; 22-Second module; 211-First protrusion; 221-Second protrusion.
[0034] In the accompanying drawings, similar reference numerals refer to the same elements. Detailed Implementation
[0035] To make the objectives and technical solutions of the present utility model clearer, the technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present utility model. All other embodiments obtained by those skilled in the art based on the described embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.
[0036] like Figure 1 As shown, a precast helical pile 1 includes a pile body 11, a through hole 12, and a groove 13. The through hole 12 is coaxially arranged with the pile body 11 and penetrates through the pile body 11. The groove 13 is continuously spirally distributed on the outer circumferential surface of the pile body 11. The groove 13 is a single helical groove, which increases the outer surface area of the pile body 11, thereby increasing the friction between the pile body 11 and the soil. Specifically, the pitch m of the groove 13 is equal.
[0037] Furthermore, the outer area of the groove 13 accounts for 1 / 6 to 1 / 2 of the side surface area of the pile body 11.
[0038] Please combine Figure 1 and Figure 2 Let A be the starting point of the groove 13 and B be the ending point. Preferably, starting point A and ending point B are located on the same plane. Starting point A is connected to or has a distance from the end face of one end of the pile body 11. Let H1 be the distance from starting point A to the end face of the pile body 11, which is 30 cm.
[0039] Please combine Figure 2 and Figure 3 The cross-section of the groove 13 is trapezoidal. The outer vertical length of the cross-section of the groove 13 is set as a, the inner vertical length is set as b, and the depth of the groove 13 is set as l. Among them, since the net thickness of the protective layer of the stressed steel bars of the precast spiral pile 1 in the construction standard is not less than 3 cm, and no additional anti-cracking measures are required when the thickness of the concrete protective layer of the longitudinal steel bars is not greater than 5 cm, and the allowable deviation of the protective layer thickness construction is ±0.5 cm, so the depth k of the groove 13 needs to satisfy 0 < l ≤ 3 cm. The trapezoidal cross-section will play a serrated role during the downward construction process, cutting the soil layer, and the cut soil can be better backfilled into the groove 13, thereby further enhancing the friction of the precast spiral pile 1. If the cross-section of the groove 13 is rectangular, that is, the inner and outer vertical lengths of the cross-section of the groove 13 are equal, it is difficult for the cut soil to be backfilled into the groove 13. If there is a gap between the groove 13 and the soil layer, the contact area between the soil and the groove 13 decreases, resulting in a decrease in friction.
[0040] The cross-section of the groove 13 is preferably an isosceles trapezoid, the inclination angle of the groove 13 is 5° - 60°, and the ratio of the outer vertical length a of the groove 13 to the net length m - a between adjacent threads is 1 / 5 - 1. For the convenience of explanation, the cross-section of the groove 13 is taken as an isosceles trapezoid for illustration. The soil layer at the construction site will be divided into i layers according to the specific actual construction situation, and the depth of the i-th layer of soil is set as l i The diameter of the selected pile body 11 is set as D, and the diameter D of the pile body 11 is a general industry friction pile specification. The side friction resistance value of the construction site is set as Q sk provided by the geological exploration personnel. The pitch is set as m. The pitch m, the outer vertical length a of the groove 13, and the inner vertical length b of the groove 13 are the main factors affecting the precast spiral pile 1. The pile side bearing capacity of the precast spiral pile is mainly provided by the shear force between the soil in the groove 13 and the outer soil. Too small pitch m will increase the number of threads, reducing the soil shear area and thus reducing the ultimate bearing capacity. When the pitch m is too large, only part of the soil in the groove 13 undergoes shear failure, and the shear strength of the soil around the pile body 11 cannot be fully exerted, reducing the ultimate bearing capacity. Therefore, selecting the optimal pitch m can maximize the ultimate bearing capacity of the precast spiral pile. Increasing the outer vertical length a and the inner vertical length b can significantly improve the bearing capacity. The bearing capacity includes side friction resistance and end resistance. In this utility model, only the side friction resistance is considered.
[0041] According to the formula for the standard value of the ultimate side friction resistance of a single pile, the side friction resistance value Q of the traditional friction pile is obtained sk = πD * ∑(q sik *l i) Equation (1), the side friction resistance value Q of the precast screw pile 1 in the present invention is derived from the above Equation (1) and the Pythagorean theorem sk The formula is:
[0042]
[0043] Where, l i is the depth of the i-th soil layer, l is the depth of the groove 13, a is the vertical length outside the groove 13, b is the vertical length inside the groove 13, S0 is the single-loop length of the groove 13, S ni is the length of the groove 13 in the i-th soil layer, q Sik is the standard value of the ultimate side friction resistance of the i-th soil layer.
[0044] The length S of the groove 13 in the i-th layer ni The formula is
[0045] Where, m is the pitch and D is the diameter of the pile body 11.
[0046] Specifically, when the installation environment and installation position of the precast screw pile 1 are determined, Q sk 、l i 、q Sik Take a definite value. When the values of the above-mentioned numerical values are determined, in order to obtain better side friction resistance and improve the bearing capacity of the precast screw pile 1, in the above-mentioned Equations (2) and (3), the structural configuration of the precast screw pile 1 is: 0 < a - b < 4 cm, 0 < l ≤ 3 cm, 25 < m < 60 cm. Preferably, a - b = 2 cm, a = 10 cm, m = 40 cm, l = 2 cm. The groove 13 shown in the above embodiment is continuously spirally distributed on the outer peripheral surface of the pile body 11. In other embodiments, the groove 13 may also be discontinuously spirally distributed on the outer peripheral surface of the pile body 11.
[0047] Please combine Figure 1 、 Figure 4 、 Figure 5 and Figure 6This utility model also provides a helical pile mold 2 for producing the precast helical pile 1. The helical pile mold 2 includes a first module 21 and a second module 22. The first module 21 and the second module 22 are the same size. The inner sides of the first module 21 and the second module 22 are respectively provided with a first protrusion 211 and a second protrusion 221. The first protrusion 211 and the second protrusion 221 are helical protrusions. After being assembled, the first protrusion 211 and the second protrusion 221 are the same as the groove 13. Material is injected into the first module 21 and the second module 22 respectively. After the material solidifies, the first module 21 and the second module 22 are assembled, and the joint is bonded and cured. Then the precast helical pile 1 is demolded. Alternatively, the first module 21 and the second module 22 can be assembled and fixed first, and then the material is injected into them. After curing, the material is demolded. Preferably, the inner sides of the first module 21 and the second module 22 are rough surfaces, thereby increasing the friction of the precast helical pile 1.
[0048] This invention can effectively reduce the occurrence of pile head cracking due to stress concentration during the construction of precast helical piles, increase the contact surface area of precast helical piles, and increase the bearing capacity by deriving and selecting values through reasonable formulas.
[0049] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.
Claims
1. A precast helical pile, characterized in that, include, pile body; The groove is a single spiral groove, which is distributed spirally on the outer circumferential surface of the pile body; The groove starts at point A and ends at point B. Point A is connected to the end face of one end of the pile or is at a distance from the end face of one end of the pile, and point B is at a distance from the end face of the other end of the pile.
2. A precast helical pile as described in claim 1, characterized in that, The distance from the termination point B to the end face of the other end of the pile is defined as H2, 30cm. <H2≤200cm。 3. A precast helical pile as described in claim 2, characterized in that, The distance from the starting point A to the end face of one end of the pile is defined as H1, 30cm. <H1≤500cm。 4. A precast helical pile as described in claim 1, characterized in that, The groove has a trapezoidal cross-section, and the vertical length of the outer side of the groove's cross-section is greater than the vertical length of the inner side of the groove's cross-section.
5. A precast helical pile as described in claim 4, characterized in that, The groove has an isosceles trapezoidal cross-section, and its depth is set to l, 0. <l≤3cm。 6. A precast helical pile as described in claim 5, characterized in that, The vertical length of the outer side of the cross-section of the groove is denoted as 'a', and the vertical length of the inner side is denoted as 'b'. <a―b<4cm。 7. A precast helical pile as described in claim 6, characterized in that, The pitch m of the grooves is equal.
8. A precast helical pile as described in claim 7, characterized in that, The side friction resistance value Q of the precast helical pile sk The formula is: The length of the groove in the i-th layer 9. A precast helical pile as described in claim 8, characterized in that, The pitch m ranges from 25. <m<60cm。 10. A precast helical pile as described in claim 9, characterized in that, a-b=2cm, a=10cm, m=40cm, l=2cm.
11. A precast helical pile as described in claim 7, characterized in that, The outer area of the groove accounts for 1 / 6 to 1 / 2 of the surface area of the side of the pile.
12. A precast helical pile as described in claim 7, characterized in that, The inclination angle of the groove is 5°-60°.
13. A precast helical pile as described in claim 7, characterized in that, The ratio of the outer vertical length a of the groove to the net length ma between adjacent threads is 1 / 5-1.
14. A precast helical pile as described in claim 1, characterized in that, It also includes a through hole, which is coaxially arranged with the pile body and penetrates the pile body.
15. A precast helical pile as described in claim 1, characterized in that, The grooves are continuously spiraled and distributed on the outer circumferential surface of the pile.
16. A precast helical pile as described in claim 1, characterized in that, The grooves are intermittently spiraling and distributed on the outer circumferential surface of the pile.
17. A precast helical pile as described in claim 1, characterized in that, The starting point A and the ending point B are located on the same plane.
18. A spiral pile mold, characterized in that, Used for producing prefabricated helical piles as described in any one of claims 1-17 above.
19. A spiral pile mold as described in claim 18, characterized in that, It includes a first module, a second module, a first protrusion, and a second protrusion. The first module and the second module are the same size. The first protrusion and the second protrusion are respectively disposed on the inner side of the first module and the second module. When the first protrusion and the second protrusion are assembled, they are the same as the groove.