Piles and pile construction methods
The pile design with a widened section and expansion joint addresses the issue of enlarged foundations by enhancing horizontal resistance and reducing construction costs.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- KAWASAKI JUKOGYO KK
- Filing Date
- 2021-11-11
- Publication Date
- 2026-06-24
AI Technical Summary
Existing enlarged-head piles, while effective in withstanding large horizontal forces, result in unnecessarily large foundations, increasing construction costs due to the enlarged pile head and foundation joint area.
A pile design featuring a widened section continuous with the pile head and a smaller-diameter extension, joined to a foundation with an expansion joint to manage horizontal forces, reducing the need for a larger foundation size.
The pile design effectively withstands large horizontal forces while minimizing the foundation size, reducing construction costs and ease of construction.
Smart Images
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Abstract
Description
Technical Field
[0001] This specification discloses a pile and a method for constructing the pile.
Background Art
[0002] For the installation of buildings such as buildings and equipment, a foundation and piles that support the foundation are used. By these piles supporting the foundation, a building can be constructed stably on soft ground. As an example of such a pile, there is an enlarged-head pile with a large pile head diameter. This enlarged-head pile is disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 61-98824).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] The pile of Patent Document 1 can withstand a large horizontal force by increasing the pile head diameter. On the other hand, by increasing the pile head diameter, the joint area between the pile head and the foundation is large. In this enlarged-head pile, the foundation becomes large. For example, when a precast pile is joined to the pile cap of the foundation, the width of the pile cap is set to 2.5Dh or more according to the pile construction method with respect to the outer diameter Dh of the pile head. Thus, the relationship between the outer diameter of the pile head and the width of the pile cap is defined. The use of such an enlarged-head pile may enlarge the foundation more than necessary. This enlargement of the foundation increases the construction cost.
[0005] What the applicant intends is to provide a pile that can withstand a large horizontal force and suppress the enlargement of the foundation, and a method for constructing this pile.
Means for Solving the Problems
[0006] A preferred pile has a pile head and a widened portion that is continuous with the pile head and wider than the pile head.
[0007] The preferred method for constructing piles is: A pile having a pile head and a widened section continuous with the pile head and wider than the pile head is buried in the ground. The foundation is connected to the pile head. [Effects of the Invention]
[0008] This pile, with its widened section, can withstand large horizontal forces while also preventing the need for a larger foundation. Furthermore, this pile can be easily constructed using a specific construction method. [Brief explanation of the drawing]
[0009] [Figure 1] Figure 1 is a conceptual diagram showing a pile according to one embodiment, along with a foundation and a structure. [Figure 2] Figure 2 is a magnified view of a portion of the pile shown in Figure 1. [Figure 3] Figure 3 is a magnified view of the pile shown in Figure 1, along with the pile cap, which is part of the foundation. [Figure 4] Figure 4 is an explanatory diagram showing the pile in Figure 1 and the distribution of the magnitude of the horizontal resistance force when the pile is subjected to a horizontal force. [Figure 5] Figure 5 is an explanatory diagram showing a pile of uniform diameter as a comparative example, and the distribution of the magnitude of the horizontal resistance force when the pile is subjected to a horizontal force. [Modes for carrying out the invention]
[0010] Preferred embodiments will be described in detail below, with reference to drawings as appropriate.
[0011] Figure 1 shows multiple piles 2 together with the foundation 4 and the structure 6. The ground 8 on which the structure 6 is installed includes a soft surface layer 8A and a firm supporting layer 8B. Each pile 2 is embedded in the ground 8. In other words, each pile 2 is embedded underground. The piles 2 are joined to the foundation 4 and extend down to the supporting layer 8B.
[0012] Pile 2 has a widened section 12, an expansion joint 16, and a small-diameter pile 18. The widened section 12 is fixed to the small-diameter pile 18. This fixing creates a pile head 10 that extends from the widened section 12 to the foundation 4, and an extension section 14 that extends from the widened section 12 into the ground. The pile head 10 is joined to the foundation 4. The widened section 12 is wider than the pile head 10. The extension section 14 extends to the supporting ground 8B. The extension section 14 is narrower than the widened section 12. The expansion joint 16 is located between the foundation 4 and the widened section 12 and is positioned on the outer circumference of the pile head 10.
[0013] As shown in Figure 2, the widening section 12 is fixed to a cylindrical small-diameter pile 18. This small-diameter pile 18 is, for example, a steel pipe. The small-diameter pile 18 is illustrative and not particularly limited. The small-diameter pile 18 may have, for example, a hollow cylindrical shape or a solid cylindrical shape, or its cross-sectional outer shape may be polygonal. The small-diameter pile 18 may also be made of concrete. In this pile 2, the extension section 14 and the pile head 10 are formed by the small-diameter pile 18, and the outer diameter of the extension section 14 and the outer diameter of the pile head 10 are the same. The relationship between the outer diameter of the extension section 14 and the outer diameter of the pile head 10 is illustrative and not particularly limited. The outer diameter of the extension section 14 may be larger than the outer diameter of the pile head 10, the same as the outer diameter of the widening section 12, or even larger than the outer diameter of the widening section 12.
[0014] The widened section 12 has a cylindrical large-diameter pile 20 and concrete 22 as a fixing material. This concrete 22 fixes the large-diameter pile 20 to the small-diameter pile 18. This fixing material does not need to be concrete 22, as long as it can fix the large-diameter pile 20 to the small-diameter pile 18. Other examples of this fixing material include grout, mortar, and resin. The large-diameter pile 20 is, for example, a steel pipe, but is not particularly limited. Also, the widened section 12 does not necessarily require concrete 22. The large-diameter pile 20 may be directly fixed to the small-diameter pile 18. Furthermore, the large-diameter pile 20 may be made entirely of concrete instead of being a steel pipe. In addition, the cross-sectional shape of the widened section 12 is not limited to a circle, but may be polygonal.
[0015] The expansion joint 16 consists of an expandable and contractible material that can expand and contract in response to external forces between the foundation 4 and the widened section 12. The expansion joint 16 consists of a member that can suppress the transmission of stress generated by external forces to the foundation 4, the pile head 10, and the foundation 4. This expansion joint 16 is made of, for example, Styrofoam (registered trademark) or other expanded polystyrene, but is not particularly limited. This expansion joint 16 only needs to be able to suppress the direct transmission of force between the foundation 4 and the widened section 12. Note that this pile 2 does not necessarily require an expansion joint 16. A soft surface ground layer 8A may be interposed between the foundation 4 and the widened section 12.
[0016] The construction method for pile 2 will now be explained with reference to Figures 1 and 2. First, a small-diameter pile 18 is embedded in the ground 8 (STEP 1). In this step (STEP 1), the small-diameter pile 18 penetrates the surface ground 8A and is supported by the supporting ground 8B. However, the small-diameter pile 18 does not necessarily have to reach the supporting ground 8B. The small-diameter pile 18 may be supported by the surface ground 8A without penetrating it.
[0017] Next, the large-diameter pile 20 is embedded in the surface ground 8A with the small-diameter pile 18 positioned radially inward (STEP2). In this step (STEP2), the upper end of the large-diameter pile 20 is positioned deeper than the upper end of the small-diameter pile 18. Concrete 22 (see FIG. 2) is placed in the radial gap between the large-diameter pile 20 and the small-diameter pile 18. In this way, the pile 2 having the pile head 10 and the widened portion 12 is formed.
[0018] An expansion 16 is formed on the outer periphery of the pile head 10 overlapping the widened portion 12 (STEP3). In this step (SETP3), for example, styrofoam (registered trademark) is wound around the outer periphery of the pile head 10 to form the expansion 16.
[0019] After this step (STEP3), the foundation 4 is formed (STEP4). This foundation 4 is joined to the pile head 10 (the upper end portion of the small-diameter pile 18) of the pile 2. Thereby, in FIG. 1, the foundation 4 is supported by the supporting ground 8B through the pile 2. After this step (STEP4), a building 6 is constructed on the foundation 4 (STEP5).
[0020] In this step (STEP1) and step (STEP2), the small-diameter pile 18 and the large-diameter pile 20 are individually embedded, but the construction method of the pile 2 is not limited to this. The pile 2 having the widened portion 12 may be prepared in advance. Instead of steps (STEP1) and (STEP2), the pile 2 prepared as a ready-made pile may be embedded in the ground 8.
[0021] Also, the embedding method of this pile 2 is not particularly limited. Examples of this embedding method include the impact method, the bored pile method, the pre-boring method, the steel pipe soil cement pile method, and the rotary pile method. Furthermore, this embedding method may be the cast-in-place pile method of constructing a reinforced concrete anti-body in a hole excavated on-site. Furthermore, as this embedding method, these methods may be combined.
[0022] [[ID=第十九]] Figure 3 shows the pile head 10 of pile 2 joined to the pile cap 24, which is part of the foundation 4. Although not shown in Figure 1, the foundation 4 includes the pile cap 24. Pile 2 is joined to the pile cap 24.
[0023] In Figure 3, the double-headed arrow Dh represents the diameter of the pile head 10. The double-headed arrow W represents the width of the pile cap 24. The dashed line Lc represents the center line between the pile 2 (pile head 10) and the pile cap 24. The double-headed arrow H represents the distance between the pile cap 24 and the widened section 12. In this pile 2, the distance H is also the height of the expansion joint 16, but the height of the expansion joint 16 is not limited to this.
[0024] In precast piles, the width W of the pile cap 24 is determined by the diameter Dh of the pile head 10, as specified in the Building Foundation Structure Design Guidelines (Architectural Institute of Japan), etc. For example, in this pile cap 24, half the width W ((1 / 2)W) is set to be 1.25 times or more the diameter Dh. Therefore, the width W of this pile cap 24 is set to be 2.5Dh or more.
[0025] Figure 4 shows a pile 2 embedded in uniform ground and the distribution of the magnitude of the horizontal resistance force of the ground when pile 2 is subjected to a horizontal force. Arrow A in Figure 4 represents the axial direction of pile 2, and symbol F represents the magnitude of the horizontal resistance force in the axial direction of pile 2. This horizontal resistance force acts in the horizontal direction. Pile 2 has a widened section 12. The widened section 12 has a larger diameter than the pile head 10 and the extended section 14. Therefore, this widened section 12 can obtain a larger horizontal resistance force than the pile head 10 and the extended section 14.
[0026] Figure 5 shows a pile 32 of uniform diameter embedded in uniform ground, and the distribution of the magnitude of the horizontal resistance force of the ground when the pile 32 is subjected to a horizontal force. The outer diameter of this pile 32 is the same as that of the small-diameter pile 18. Arrow A in Figure 5 represents the axial direction of the pile 32, and symbol F represents the magnitude of the bearing force in the axial direction of the pile 32. This pile 32 has no widened section 12 and has a uniform outer diameter in the axial direction. A uniform horizontal resistance force in the axial direction can be obtained with this pile 32.
[0027] As is clear from Figures 4 and 5, pile 2, supported by the ground 8, exerts a large horizontal resistance force due to pile 32. By having a widened section 12, pile 2 can increase the horizontal resistance force (horizontal spring) which depends on the hardness of the ground 8 and the pile diameter. Compared to pile 32, pile 2 can withstand larger horizontal forces and reduce horizontal displacement.
[0028] On the other hand, in this pile 2, the pile head 10, which has a smaller diameter than the widened section 12, is joined to the pile cap 24. This pile 2 can be joined to a pile cap 24 that fits the outer diameter of the pile head 10, while still having a widened section 12. This pile 2 can reduce the edge distance of the pile cap 24 to which it is joined (width (1 / 2)W in Figure 3). This pile 2 has a small joining area with the pile cap 24. This pile 2 can suppress the need to enlarge the pile cap 24.
[0029] This applies not only to the pile cap 24, but also, for example, when the pile 2 is joined to another flat foundation, the contact area with this other foundation is small. The pitch at which multiple piles 2 are lined up can also be made smaller compared to that of enlarged-head piles joined with large-diameter pile heads. As a result, the size of the pile 2 can be suppressed not only for the pile cap 24, but also for other foundations.
[0030] This pile 2 does not necessarily have to have an expansion joint 16. However, by interposing the expansion joint 16 in this pile 2, the intrusion of rocks, stones, etc., between the widened section 12 and the foundation 4 is suppressed. This expansion joint 16 more reliably suppresses the direct transmission of force between the widened section 12 and the foundation 4. From this viewpoint, it is preferable that the pile 2 has an expansion joint 16.
[0031] In this pile 2, the length of the widened section 12 is shorter than the length of the extended section 14. The extended section 14, which has a smaller outer diameter than the widened section 12, extends down to the supporting ground 8B. Compared to the case where the large-diameter pile 20 forming the widened section 12 is extended down to the supporting ground 8B, this pile 2 is easier to bury and reduces the amount of excavated soil generated during burying. This construction method of pile 2 contributes to reducing construction costs.
[0032] [Disclosure items] Each of the following items is a disclosure of a preferred embodiment.
[0033] [Item 1] A pile 2 having a pile head 10 and a widened section 12 that is continuous with the pile head 10 and is wider than the pile head 10.
[0034] [Item 2] Pile 2 of item 1, having an expansion joint 16 located between the foundation 4 and the widened section 12 and on the outer circumference of the pile head 10.
[0035] [Item 3] A pile 2 having a pile head 10 and a widened section 12 that is continuous with the pile head 10 and wider than the pile head 10 is buried in the ground. The foundation 4 is connected to the pile head 10. Installation method for pile 2.
[0036] [Item 4] The pile 2 is buried in the ground. A small-diameter pile 18, including the pile head 10 and having a width smaller than the widened section 12, is buried in the ground. The large-diameter pile 20, including the widened section 12, is buried in the ground with the small-diameter pile 18 positioned radially inward, and the upper end of the large-diameter pile 20 positioned deeper than the upper end of the small-diameter pile 18. The construction method for pile 2 of item 3, including the construction method for item 3. [Industrial applicability]
[0037] The aforementioned pile 2 can be widely applied to structures supported by piles, such as buildings and equipment. [Explanation of Symbols]
[0038] 2...Pile 4...Fundamentals 6...Buildings 8...Ground 10...Pile head 12. Widening section 14...Extension part 16.. Expansion 18. Small diameter stakes 20. Large-diameter piles
Claims
[Claim 1] A pile having a pile head and a widened section continuous with the pile head and wider than the pile head is buried in the ground. The foundation is joined to the pile head with the foundation and the upper end of the widened section separated. The aforementioned piles are buried in the ground. A small-diameter pile, including the pile head and having a width smaller than the widened section, is buried in the ground. The large-diameter pile included in the widened section is buried in the ground with the small-diameter pile positioned radially inward, the upper end of the large-diameter pile positioned deeper than the upper end of the small-diameter pile, and the upper end of the widened section separated from the foundation. A method for constructing piles, including [specific details omitted].