Hang basic structure

Abstract

To provide a pile foundation structure and its construction method which can secure required clearance between precast concrete foundation members and foundation pile heads even if foundation pile positions are shifted.SOLUTION: A pile foundation structure 1 includes foundation piles 10 and precast concrete foundation members 20 provided on the foundation piles 10 . The pile heads 11 of the foundation piles 10 protrude upward from the ground surface 2, and the bottom surfaces of the foundation members 20 are formed with recesses 22 in which the pile heads 11 of the foundation piles 10 are accommodated. And the pile foundation structure 1 includes level adjustment members 40 provided on the discarded concrete layer 3 around the foundation piles 10 and supporting the foundation members 20, cover members 30 made of concrete covering the pile heads 11 of the foundation piles 10 and filling parts 42 formed by filling non-shrinkable grout material between the cover members 30 and the recesses 22 of the base member 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pile foundation structure including a foundation pile and a precast concrete foundation member provided on the foundation pile.

Background Art

[0002] Conventionally, a precast concrete foundation member is placed on a foundation pile, and a filler is filled in the gap between the foundation pile and the foundation member to integrate the foundation pile and the foundation member (see Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a pile foundation structure and a construction method thereof that can adjust the clearance between the precast concrete foundation member and the pile head of the foundation pile even when the position of the foundation pile is displaced.

Means for Solving the Problems

[0005] The inventors of the present invention have arrived at the present invention by focusing on the fact that, as a pile foundation structure in which a precast concrete foundation member is installed on the pile head of a foundation pile, a cover member is constructed from a cement-based material so as to cover the pile head of the foundation pile, with the position of the top and sides determined so as to ensure a predetermined clearance between it and the recess of the foundation member to be installed in a later process, and then the foundation member is installed and a filler material is filled between the cover member and the recess of the foundation member, so that even if the height or horizontal position of the foundation pile is shifted due to construction errors, these construction errors can be absorbed by joining the foundation pile and the foundation member via the cover member. The pile foundation structure of the first invention (for example, the pile foundation structure 1 described later) is a pile foundation structure comprising a foundation pile (for example, the foundation pile 10 described later) and a precast concrete foundation member (for example, the foundation member 20 described later) provided on the foundation pile, wherein the pile head of the foundation pile (for example, the pile head 11 described later) protrudes upward from the ground surface (for example, the ground surface 2 described later), and a recess (for example, the recess 22 described later) is formed on the lower surface of the foundation member in which the pile head of the foundation pile is accommodated, and the ground surface around the foundation pile or on the ground surface The foundation member is characterized by comprising: a leveling material (e.g., leveling material 40 described later) provided on a lean concrete layer (e.g., lean concrete layer 3 described later) to support the foundation member; a cover member (e.g., cover member 30 described later) made of a cement-based material (e.g., concrete described later) to cover the pile head of the foundation pile; and a filling portion (e.g., filling portion 42 described later) formed by filling a filler material between the cover member and the recess of the foundation member, wherein the foundation member is joined to the foundation pile via the filling portion and the cover member.

[0006] The underside of the precast concrete foundation member has a recess formed to accommodate the pile head of the foundation pile. Conventionally, if the position of the foundation pile shifted, the gap (clearance) between this recess in the foundation member and the pile head of the foundation pile could become excessive. In this case, filling this gap with filler material would require a large amount of filler material, which increased the construction cost of the pile foundation structure. Therefore, according to this invention, a cover member is constructed to cover the pile head of the foundation pile. At this time, the position of the top surface and side surface of the cover member is constructed so as to ensure a predetermined clearance between it and the recess of the foundation member to be attached in a later step. Next, a leveling material is installed on the ground surface around the foundation pile or on the lean concrete layer on the ground surface, and the foundation member is placed on this leveling material. This ensures a predetermined clearance between the top surface and side surface of the cover member and the recess of the foundation member. After that, a filler material is filled into this gap to form a filled section, and the foundation member is joined to the foundation pile via the filled section and the cover member. Thus, even if the height or horizontal position of the foundation pile is shifted due to construction errors, the cover member can absorb the construction errors and adjust the clearance between the precast concrete foundation member and the pile head of the foundation pile. As a result, the amount of filler material to be filled into this clearance can be reduced, and the pile foundation structure can be constructed at a low cost.

[0007] The pile foundation structure of the second invention is characterized in that the pile head of the foundation pile is covered with a pile head cap (for example, a pile head cap 31 described later) to form a gap on the side surface of the pile head, and the cover member is formed by pouring a cement-based material onto the pile head cap.

[0008] According to this invention, by forming a gap on the side of the pile head with the pile head cap, the foundation pile and the foundation member are semi-rigidly connected, ensuring structural stability during earthquakes. Therefore, by using this pile head cap as a bottom formwork and pouring cement-based material on top of the pile head cap, the cover member can be constructed efficiently, and the foundation pile and the foundation member are semi-rigidly connected, ensuring structural stability during earthquakes.

[0009] The third invention is a method for constructing a pile foundation structure comprising a foundation pile and a precast concrete foundation member provided on the foundation pile, and is characterized by comprising the steps of: constructing a cover member made of a cement-based material so as to cover the pile head of the foundation pile that protrudes upward from the ground surface (for example, steps S1 and S2 described later); installing a leveling material on the ground surface or on a lean concrete layer on the ground surface to adjust the height position of the foundation member (for example, step S3 described later); preparing a foundation member having a recess formed on its lower surface, placing the foundation member on the leveling material, and accommodating the cover member provided on the pile head of the foundation pile in the recess of the foundation member (for example, step S4 described later); and filling a filling material (for example, a non-shrink grout material described later) between the cover member and the recess of the foundation member to form a filling section, thereby joining the foundation member to the foundation pile via the filling section and the cover member (for example, step S5 described later).

[0010] According to this invention, a cover member is constructed to cover the pile head of the foundation pile. At this time, the position of the top surface and side surface of the cover member is constructed so as to ensure a predetermined clearance between it and the recess of the foundation member to be attached in a later step. Next, a leveling material is installed on the ground surface around the foundation pile or on the lean concrete layer on the ground surface, and the foundation member is placed on this leveling material. This ensures a predetermined clearance between the top surface and side surface of the cover member and the recess of the foundation member. After that, a filler material is filled into this gap to form a filled section, and the foundation member is joined to the foundation pile via the filled section and the cover member. Therefore, even if the height or horizontal position of the foundation pile is shifted due to construction errors, the cover member can absorb the construction errors and adjust the clearance between the precast concrete foundation member and the pile head of the foundation pile. As a result, the amount of filler material to be filled into this clearance can be reduced, and the pile foundation structure can be constructed at a low cost. Furthermore, since the cover member is constructed by pouring concrete before installing the foundation member, unlike the case where the cover member is constructed by filling the gap between the pile head of the foundation pile and the recess of the foundation member with concrete after the foundation member has been installed, a relatively thin and planar cover member can be constructed around the pile head. [Effects of the Invention]

[0011] According to the present invention, even if the position of the foundation pile is misaligned, a pile foundation structure and a method for constructing the same can be provided, which allows for adjustment of the clearance between the precast concrete foundation member and the pile head of the foundation pile by providing a cover member that covers the pile head. [Brief explanation of the drawing]

[0012] [Figure 1] This is a longitudinal cross-sectional view of a pile foundation structure according to the first embodiment of the present invention. [Figure 2] Figure 1 is a cross-sectional view AA of the pile foundation structure according to the first embodiment. [Figure 3] Figure 1 is a partially enlarged view of the pile foundation structure according to the first embodiment. [Figure 4] This is a flowchart of the construction method for the pile foundation structure according to the first embodiment. [Figure 5] This is an explanatory diagram of the construction method of the pile foundation structure according to the first embodiment (Part 1: The state in which a pile head cap is placed over the pile head of the foundation pile and a lean concrete layer is formed). [Figure 6] This is an explanatory diagram of the construction method of the pile foundation structure according to the first embodiment (part 2: state in which concrete has been poured on top of the pile head cap to construct the cover member). [Figure 7] This is an explanatory diagram of the construction method of the pile foundation structure according to the first embodiment (part 3: state with leveling material placed on top of the lean concrete layer). [Figure 8] This is a longitudinal cross-sectional view of a pile foundation structure according to a second embodiment of the present invention. [Modes for carrying out the invention]

[0013] The present invention relates to a pile foundation structure that connects a foundation pile to a precast concrete foundation member. Specifically, a cover member made of cement-based material is constructed on the pile head of the foundation pile, and at this time, a predetermined clearance is ensured between the cover member and the recess of the foundation member to be installed in a later step. After that, the foundation member is installed, and a filling portion is provided between the cover member and the recess of the foundation member. The first embodiment is a pile foundation structure in which the foundation pile and the foundation member are semi-rigidly connected by providing a gap between the side surface of the pile head of the foundation pile and the recess (cover member) of the foundation member. The second embodiment is a pile foundation structure in which the foundation pile and the foundation member are rigidly connected by not providing a gap between the pile head of the foundation pile and the recess (cover member) of the foundation member. Embodiments of the present invention will be described below with reference to the drawings. In the following description of embodiments, identical components will be denoted by the same reference numerals, and their descriptions will be omitted or simplified. [First Embodiment] Figure 1 is a longitudinal cross-sectional view of a pile foundation structure 1 according to the first embodiment of the present invention. Figure 2 is a cross-sectional view AA of the pile foundation structure 1 in Figure 1. Figure 3 is a partially enlarged view of the pile foundation structure 1 in Figure 1. The pile foundation structure 1 comprises a precast concrete foundation pile 10 and a precast concrete foundation member 20 installed on top of the foundation pile 10. The foundation piles 10 have pile heads 11 that protrude upward from the ground surface 2. Crushed stone is laid on top of this ground surface 2, and concrete is poured on top of this crushed stone to form a lean concrete layer 3. A cover member 30 made of concrete, a cement-based material, is provided on top of the pile head 11 of the foundation pile 10, covering the top and sides of the pile head 11. Specifically, a pile head cap 31 is placed over the pile head 11 of the foundation pile 10. The pile head cap 31 comprises a cap body 32 that covers the top surface of the pile head 11, and a wall portion 33 that extends downward from the periphery of the cap body 32 and covers the sides of the pile head 11. A gap S is formed between this wall portion 33 and the sides of the pile head 11. Concrete, a cement-based material, is poured on top of the pile head cap 31 to form the cover member 30.

[0014] The base member 20 serves as a footing, and the foundation beam 4 and the column 5 are attached to this base member 20. A recess 22 for accommodating the pile head 11 of the foundation pile 10 is formed on the lower surface 21 of the base member 20. This recess 22 is composed of a bottom surface (upper surface) 23 and a wall surface 24 around the bottom surface 23. The base member 20 is provided with a grout injection pipe 25 extending from the outside to the central portion of the bottom surface 23 of the recess 22 and a grout discharge pipe 26 extending from the peripheral edge portion of the bottom surface 23 of the recess 22 to the outside. On top of the waste concrete layer 3, a level adjusting material 40 with an adjustable upper surface height is arranged. This level adjusting material is formed by laminating thin metal plates, and the height position of the upper surface can be adjusted by changing the number of thin plates to be laminated. Also, around the lid member 30 on top of the waste concrete layer 3, an elastic deformable resin-made anti-slip gasket 41 is arranged.

[0015] The base member 20 is placed on the level adjusting material 40, and thereby, the base member 20 is supported by the level adjusting material 40. At this time, the lid member 30 is accommodated in the recess 22 of the base member 20, and the lower surface 21 of the base member 20 crushes the anti-slip gasket 41 on the waste concrete layer 3. The clearance between the upper surface of the lid member 30 and the bottom surface 23 of the recess 22 is d1, and the clearance between the side surface of the lid member 30 and the wall surface 24 of the recess 22 is d2. Between the lid member 30 and the recess 22 of the base member 20, a non-shrinking grout material is filled using the grout injection pipe 25 and the grout discharge pipe 26, and a filling portion 42 is formed. Thereby, the base member 20 is joined to the foundation pile 10 through the filling portion 42 and the lid member 30.

[0016] Hereinafter, the construction method of the pile foundation structure 1 will be described while referring to the flowchart of FIG. 4. As an initial state, it is assumed that the foundation pile 10 protrudes upward from the ground surface 2. In step S1, as shown in Figure 5, a pile head cap 31 is placed over the pile head 11 of the foundation pile 10. This creates a gap S between the wall portion 33 and the side surface of the pile head 11. Next, crushed stone is laid on the ground surface 2, and then concrete is poured to form a lean concrete layer 3. When forming the lean concrete layer 3, the wall portion 33 of the pile head cap 31 is used as a side formwork (formwork on the pile head 11 side) for laying the crushed stone and pouring the concrete.

[0017] In step S2, as shown in Figure 6, the pile head cap 31 is used as the bottom formwork, and concrete is poured on top of the pile head cap 31 to construct the lid member 30. Here, the positions of the top surface and sides of the lid member 30 are determined so as to ensure predetermined clearances d1 and d2 between them and the recesses 22 of the foundation member 20 to be installed in a later step. Then, according to the determined position of the sides, side formwork 34 is erected on the lean concrete layer 3, and concrete is poured inside the side formwork 34 up to the determined height of the top surface of the lid member 30.

[0018] In step S3, as shown in Figure 7, a leveling material 40 is placed on top of the lean concrete layer 3 to adjust the height of the foundation member 20. Also, a grout-stopping gasket 41 is placed around the lid member 30 on top of the lean concrete layer 3. In step S4, the foundation member 20 is placed on the leveling material 40, as shown by the arrow in Figure 7. As a result, as shown in Figure 1, the cover member 30 provided on the pile head 11 of the foundation pile 10 is accommodated in the recess 22 of the foundation member 20, and clearances d1 and d2 are secured between the cover member 30 and the recess 22 of the foundation member 20. In addition, the lower surface 21 of the foundation member 20 crushes the grout-stopping gasket 41 on the lean concrete layer 3.

[0019] In step S5, as shown in Figure 1, a non-shrink grout material is filled between the lid member 30 and the recess 22 of the foundation member 20 to form a filled section 42. Specifically, the non-shrink grout material is injected into the recess 22 from the outside through the grout injection pipe 25. This injection of the non-shrink grout material is continued until it can be confirmed that the non-shrink grout material is discharged to the outside through the grout discharge pipe 26. In this way, the foundation member 20 is joined to the foundation pile 10 via the filled section 42 and the lid member 30.

[0020] This embodiment provides the following effects. (1) A cover member 30 is constructed to cover the pile head 11 of the foundation pile 10. At this time, the position of the upper surface and side surfaces of the cover member 30 is constructed so as to secure predetermined clearances d1 and d2 between it and the recess 22 of the foundation member 20. Next, a leveling material 40 is placed on the lean concrete layer 3 on the ground surface 2 around the foundation pile 10, and the foundation member 20 is placed on this leveling material 40. This ensures predetermined clearances d1 and d2 between the upper surface and side surfaces of the cover member 30 and the recess 22 of the foundation member 20. After that, non-shrink grout material is filled into the gap of these clearances d1 and d2 to form a filled section 42, thereby joining the foundation member 20 to the foundation pile 10 via the filled section 42 and the cover member 30. Therefore, even if the height or horizontal position of the foundation pile 10 is shifted due to construction errors, the cover member 30 can absorb the construction errors and ensure predetermined clearances d1 and d2 between the precast concrete foundation member 20 and the pile head 11 of the foundation pile 10. As a result, the amount of non-shrink grout material to be filled into this clearance can be reduced, allowing the pile foundation structure 1 to be constructed at a low cost.

[0021] (2) By forming a gap S on the side surface of the pile head 11 with the pile head cap 31, the foundation pile 10 and the foundation member 20 are semi-rigidly connected, ensuring structural stability during earthquakes. Therefore, by using the pile head cap 31 as a bottom formwork and pouring concrete on top of the pile head cap 31, the cover member 30 can be constructed efficiently, and the foundation pile 10 and the foundation member 20 are semi-rigidly connected, ensuring structural stability during earthquakes.

[0022] [Second Embodiment] Figure 8 is a longitudinal cross-sectional view of the pile foundation structure 1A according to the second embodiment of the present invention. In this embodiment, there is no gap around the pile head 11 of the foundation pile 10, and the foundation pile 10 and the foundation member 20 are rigidly connected, which is different from the first embodiment. In other words, the pile head 11 of the foundation pile 10 is not provided with a pile head cap. Instead, a bottom formwork, which is a sacrificial formwork (not shown), is erected on top of the pile head 11, and concrete, which is a cement-based material, is poured in place on top of this bottom formwork to provide a cover member 30A. As a result, the cover member 30A is in close contact with the side surface of the pile head 11 of the foundation pile 10. According to this embodiment, in addition to the effect of (1) described above, the following effects are obtained. (3) By rigidly connecting the foundation pile 10 and the foundation member 20 via the cover member 30 and the filling portion 42 without leaving a gap around the pile head 11 of the foundation pile 10, excellent structural stability can be ensured.

[0023] Furthermore, the present invention is not limited to the embodiments described above, and any modifications, improvements, etc., that can achieve the objectives of the present invention are included within the scope of the present invention. In the embodiments described above, no reinforcing bars or steel materials are placed between the foundation pile 10 and the foundation member 20. However, the invention is not limited to this, and vertical reinforcing bars may be provided as pull-out resistance members for the foundation pile 10, with one end of the vertical reinforcing bar anchored inside the foundation pile 10 and the other end anchored to the foundation member 20 or extending upward through the foundation member 20. Furthermore, in the embodiments described above, reinforcing bars or steel materials are not embedded inside the foundation member 20. However, the invention is not limited to this, and reinforcing bars or steel materials corresponding to the main beam reinforcement of the foundation beam or the main column reinforcement of the column material may be embedded inside the foundation member 20. Furthermore, in the embodiments described above, the leveling material 40 was constructed by laminating thin metal plates, but it is not limited to this, and mortar boards may be used as the leveling material, or cement-based self-leveling material may be mixed at the construction site and leveled with a trowel or other tool to form the leveling material.

[0024] Furthermore, although the lid member 30 was formed of concrete in the above-described embodiment, it is not limited to this and may be formed of mortar or fiber-reinforced concrete. Furthermore, in each of the embodiments described above, the cover member 30 was formed by pouring concrete on-site, but it is not limited to this, and may be made of precast concrete. In this case, for example, the cover member 30 is manufactured in a factory according to the displacement dimension of the pile head 11 of the foundation pile 10, transported to the site, and installed on the pile head 11 of the foundation pile 10. Furthermore, in the above-described embodiment, in step S3, as shown in Figure 7, the grout-stopping gasket 41 was placed on the lean concrete layer 3 before the foundation member 20 was placed. However, it is also possible to place the grout-stopping gasket without placing it, by providing the grout-stopping gasket 41 or a protrusion equivalent to the grout-stopping gasket 41 on the bottom surface of the foundation member 20, and then placing the foundation member 20 in this state. [Explanation of Symbols]

[0025] S... Gap around the foundation pile d1... Clearance between the top surface of the cover member and the bottom surface of the recess d2…Clearance between the side surface of the lid member and the wall surface of the recess 1, 1A...Pile foundation structure 2...Ground surface 3...Lean concrete layer 4...Foundation beam 5...Column 10...Foundation pile 11...Pile cap 20...Foundation member 21...Underside of foundation member 22...Recess 23...Bottom surface of recess 24...Wall surface of recess 25...Grout injection pipe 26...Grout discharge pipe 30, 30A... Cover member 31... Pile head cap 32... Cap body 33... Wall section 34... Side formwork 40...Leveling material 41...Slag-blocking gasket 42...Filling section

Claims

1. A pile foundation structure comprising foundation piles and precast concrete foundation members provided on the foundation piles, The pile head of the foundation pile protrudes upward from the ground surface, A recess for accommodating the head of the foundation pile is formed on the lower surface of the foundation member, A level adjustment member that is provided on the ground surface around the foundation pile or on a basal concrete layer on the ground surface and supports the foundation member; A cover member made of a cement-based material that covers the head of the foundation pile; a filling portion formed by filling a filler material between the cover member and the recessed portion of the base member, A pile foundation structure characterized in that the foundation member is joined to the foundation pile via the filling portion and the cover member.

2. The pile head of the foundation pile is covered with a pile head cap to form a gap on the side of the pile head, 2. The pile foundation structure according to claim 1, wherein the cover member is formed by pouring a cement-based material onto the pile head cap.

3. A method for constructing a pile foundation structure comprising foundation piles and precast concrete foundation members provided on the foundation piles, A step of constructing a cover member made of a cement-based material so as to cover the head of the foundation pile protruding upward from the ground surface; a step of installing a level adjustment material on the ground surface or a basal concrete layer on the ground surface to adjust the height position of the foundation member; A step of preparing a foundation member having a recess formed on its lower surface, placing the foundation member on the level adjustment material, and accommodating a cover member provided on the pile head of the foundation pile in the recess of the foundation member; A method for constructing a pile foundation structure, comprising a step of filling a filler material between the cover member and the recess of the foundation member to form a filling section, and joining the foundation member to the foundation pile via the filling section and the cover member.

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