Joint structure

Abstract

To provide a joint structure capable of more reliably filling a filling material which has a joint where concrete members are joined together by filling a recess with a filler with a convex part formed on the upper end of a lower concrete member inserted into the recess formed on the lower surface of an upper concrete member.SOLUTION: A joint structure 1 for joining a footing 2 and a pile 3 includes: a recess 21 of a square in plan view formed in the lower face of the footing 2; an injection hole 22 extending from the top face of the footing 2 to the center of the recess 212; multiple air holes 23 extending from the top face of the footing 2 to the recess 21; a square-shaped pile head 31 that is inserted into the recess 21; and a filling material 4 that is filled from the injection hole 22 into a gap between the recess 21 and the pile head 31. The air hole 23 opens directly above the area that is inside the periphery of the pile head 31 and outside a circle inscribed in the periphery of the pile head 31.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a joining structure between concrete members.

Background Art

[0002] In construction work, precast members may be used for the purpose of shortening the construction period. It is common for precast members to be joined to other concrete members formed by in-situ concrete or other precast members via mortar or the like. For example, as shown in FIG. 5, as a joining structure 100 between a precast footing member 120 and a concrete pile, a recess 121 is formed on the bottom surface of the footing member 120, and in a state where the pile head (protrusion 131) is inserted into the recess 121, a filler 140 such as mortar may be filled in the gap between the recess 121 of the footing member 120 and the pile head 131 (see, for example, Patent Document 1). In such a joining structure 100, since the filling state of the filler 140 in the recess 121 cannot be visually confirmed, the filler 140 is injected from an injection hole 122 formed near the center of the recess 121, and the discharge of the filler 140 is confirmed from a plurality of air holes 123 formed near the edge (corner) of the recess 121, and it has generally been considered that the filling is completed. The filler material 140 injected through the injection hole 122 formed near the center of the recess 121 spreads concentrically on the upper surface of the protrusion 131, as shown in Figure 6(a), reaches the edge of the protrusion 131, and flows down from the edge of the protrusion 131, as shown in Figure 6(b). The filler material 140 that flows down from the edge of the protrusion 131 flows between the inner wall surface of the recess 121 and the side surface of the protrusion 131, as shown in Figure 6(c). If the protrusion 131 is rectangular, the filler material 140 reaches all four sides of the protrusion 131 and flows down, then flows between the inner wall surface of the recess 121 and the side surface of the protrusion 131 to reach the air hole 123. Therefore, the filler material 140 does not necessarily spread across the entire upper surface of the protrusion 131 before flowing down. Even if discharge of the filler material 140 from the air holes 123 formed on the edge of the recess 121 is confirmed, there is a risk that unfilled areas (air pockets) may occur in the central part (region 133) of the air holes 123. Consequently, there is no easy way to determine when the filler material 140 has completed filling the gap between the protrusion 131 and the recess 121. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-186154 [Overview of the project] [Problems that the invention aims to solve]

[0004] From this perspective, the object of the present invention is to propose a joint structure that enables more reliable filling of a filler material in a joint between concrete members, in which a protrusion formed on the upper end of a lower concrete member is inserted into a recess formed on the lower surface of an upper concrete member, and a filler material is filled into the recess. [Means for solving the problem]

[0005] To solve the aforementioned problems, the present invention provides a joining structure for joining an upper concrete member disposed on the upper side and a lower concrete member disposed on the lower side, comprising a square-shaped recess in plan view formed on the lower surface of the upper concrete member, and extending from the side or top surface of the upper concrete member to the center of the recess. 1 The structure comprises an injection hole, a plurality of air holes extending from the side or top surface of the upper concrete member to the recess, a square-shaped protrusion in plan view that is inserted into the recess formed on the upper part of the lower concrete member, and a filler material that fills the gap between the recess and the protrusion from the injection hole. The air holes open on the inside of the periphery of the protrusion and directly above the region outside the circle inscribed in the periphery of the protrusion. Furthermore, when point P is the vertex of the square in plan view of the protrusion, and point A is the intersection of the line connecting the center O of the protrusion and point P with the circle inscribed on the periphery of the protrusion, it is desirable that the air vent be located within a rectangular area whose diagonal is the line connecting point P and point A, and more preferably located near point B, which is the midpoint between point P and point A.

[0006] When constructing such a joint structure, the filler injected from near the center of the recess spreads concentrically on the upper surface of the protrusion, flows down from each side of the protrusion, reaches the inner wall surface of the recess, and then flows between the inner wall surface of the recess and the side surface of the protrusion. The air holes are formed on the side of the vertices of the square in plan view of the protrusion, and in the area outside the concentrically spreading filler, so it is difficult for unfilled areas to form. In other words, by forming air holes in a position where the filler is unlikely to wrap around, and by confirming the outflow of the filler from these air holes, it is possible to prevent the formation of unfilled areas (air pockets). [Effects of the Invention]

[0007] According to the joining structure of the present invention, in a joint where concrete members are joined together by inserting a protrusion formed on the upper end of a lower concrete member into a recess formed on the lower surface of an upper concrete member and then filling the recess with a filler, it becomes possible to more reliably fill the filler. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows a joint structure according to an embodiment of the present invention, where (a) is a cross-sectional view and (b) is a cross-sectional view of (a) AA. [Figure 2] This is an explanatory diagram of the location where air vents are formed. [Figure 3] This is a cross-sectional view showing a method for constructing a pile foundation structure, where (a) is the pile construction process, (b) is the pile head treatment process, and (c) is the foundation placement process and joining process. [Figure 4] This diagram illustrates the injection process of the filling material, where (a) is the initial injection stage, (b) is the stage when the filling material has reached all four sides of the pile head, and (c) is the stage when the filling material is flowing through the gap between the side surface of the pile head and the inner surface of the recess. [Figure 5] This is a cross-sectional view showing an example of a conventional joint structure. [Figure 6] This diagram illustrates the filling status of the filling material in a conventional joint structure, where (a) is the initial injection stage, (b) is the stage when the filling material has reached all four sides of the pile head, and (c) is the situation when the filling material is flowing through the gap between the side surface of the pile head and the inner surface of the recess. [Modes for carrying out the invention]

[0009] This embodiment describes a case in which the pile head 31 of a pile (lower concrete member) 3 and a precast footing (upper concrete member) 2 are joined in a pile foundation structure. Figure 1 shows the joining structure 1 between the footing 2 and the pile 3. In this embodiment, the case in which the pile head 31 and the cap member 32 of the pile 3 constitute a protrusion that is inserted into the recess 21 of the footing 2 is described. As shown in Figures 1(a) and (b), a square-shaped recess 21 is formed on the lower surface of the footing 2 in plan view. The footing 2 also has an injection hole 22 and a number of air holes 23. The injection hole 22 is formed to extend from the side surface of the footing 2 to the recess 21. The air holes 23 are also formed to extend from the side surface of the footing 2 to the recess 21. The upper end (protrusion) of the pile 3 is insertable into the recess 21 and has a square shape in plan view. The pile head 31 protrudes from the floor surface 5 on which the footing 2 is placed. In this embodiment, the pile head 31 has a square-shaped cap member 32 in plan view that can be inserted into the recess 21 as a pile head treatment. The joint structure 1 is formed by inserting the pile head 31 (cap member 32) into the recess 21 and filling the gap between the recess 21 and the pile head 31 (cap member 32) with a filler material 4 injected through the injection hole 22. The filler material 4 can be any material that is fluid and suitable for sealing gaps and exhibits a predetermined strength after hardening; for example, non-shrink mortar can be used.

[0010] In this embodiment, the injection hole 22 is formed near the center of the recess 21. Figure 2 shows the location where the air holes 23 are formed. As shown in Figure 2, the air holes 23 are located on the inside of the periphery of the cap member 32 (pile head 31) and open directly above the region 33 outside the circle C that is inscribed in the periphery of the cap member 32. Let P be the vertex (angle) of the cap member 32 (pile head 31), and let A be the intersection of the line L connecting the center O of the cap member 32 and point P and the circle C inscribed on the periphery of the pile head 31 (the intersection point in the upper right of the paper in Figure 2). Then, an air hole 23 is provided near point B, which is the midpoint between point P and point A. In this embodiment, point B is provided within the region of a rectangle E with the line connecting point P and point A as its diagonal, more specifically, at the midpoint of point P and point A (the center of rectangle E). In this case, if the coordinates of point P are (0,0) and the length of one side of the cap member 32 is D, then the coordinates of point A are (D(2-2 0.5 ) / 4,D(2-2 0.5 ) / 4), the coordinates of point B are (D(2-2 0.5 ) / 8,D(2-2 0.5 ) / 8)

[0011] The following describes a method for constructing a pile foundation structure using the joint structure 1 of this embodiment. The method for constructing a pile foundation structure according to this embodiment includes a pile construction step, a pile head treatment step, a foundation placement step, and a joining step. Figure 3 shows the work process for constructing a pile foundation structure. The pile construction process is a process of constructing pile 3 as shown in Fig. 3(a). In this embodiment, pile 3 is constructed by pressing a cylindrical precast member into the ground G, but the type and construction method of pile 3 are not limited. The pressing of pile 3 is performed using a rotary pressing device (not shown). After the construction of pile 3 is completed, the ground surface GL around the pile head 31 is dug down to expose the pile head 31 and to level the unevenness of the ground surface GL (the bedding surface). Note that when the construction of pile 3 is stopped at the position where the pile head 31 is exposed, it is not necessary to dig down the ground surface GL.

[0012] The pile head treatment process is a process of forming a cap member 32 on the pile head 31 of pile 3 as shown in Fig. 3(b). The cap member 32 is formed in a state of covering the pile head 31 so as to be in close contact with the lower surface of the cap member 32. The cap member 32 is a block-shaped member having a rectangular shape in plan view with a size that can be inserted into the recess 21, and a frustum-shaped depression into which the pile head 31 can be inserted is formed on the bottom surface. After forming the cap member 32 on the pile head 31, the ground material (crushed stone, earth and sand, etc.) 51 is spread evenly around the lower end of the cap member 32 to close the gap between the lower end edge of the cap member 32 and the ground surface G0 and to temporarily fix the cap member 32. After temporarily fixing the cap member 32, leveling concrete 52 is placed as necessary.

[0013] The foundation installation process is a process of installing the footing 2 made of a precast concrete member as shown in Fig. 3(c). The footing 2 is installed from above the pile head 31 so as to cover the cap member 32 (pile head 31) in the recess 21.

[0014] The joining process is a process of joining the pile head 31 and the footing 2. The joining of the pile head 31 and the footing 2 is performed by injecting the filling material 4 from the injection hole 22 and filling the gap between the recess 21 and the cap member 32 (pile head 31) as shown in FIG. 3(c). As the filling material 4 is injected, the air in the gap between the recess 21 and the cap member 32 is exhausted from the air holes 23. When the gap between the recess 21 and the cap member 32 is filled with the filling material 4, the filling material 4 is discharged from the air holes 23. When the discharge of the filling material 4 is confirmed from all the air holes 23, it is considered that the recess 21 is filled with the filling material 4, and the injection of the filling material 4 is terminated. In addition, as shown in FIG. 4(a), the filling material 4 injected from the injection hole 22 spreads concentrically on the upper surface of the pile 3 (cap member 32), and then reaches the edge (side) of the cap member 32 as shown in FIG. 4(b). When the filling material 4 reaches the edge of the cap member 32, it flows down from the edge (four sides) of the cap member into the gap (groove T) between the side surface of the cap member 32 and the inner wall surface of the recess 21. Then, the filling material 4 that has flowed down into the gap (groove T) flows through the gap (groove T) between the inner wall surface of the recess 21 and the side surface of the cap member 32 as shown in FIG. 4(c). When the gap (groove T) between the inner wall surface of the recess 21 and the side surface of the cap member 32 is filled with the filling material 4, the filling material 4 that has overflowed from the gap (groove T) is inside the inner periphery of the upper surface of the cap member 32 (pile head 31) and outside the circle C (see FIG. 2) that is inscribed in the periphery of the cap member 32 (pile head 31), and the inside of the recess 21 is filled with the filling material 4 (see FIG. 1).

[0015] In the joining structure 1 of the present embodiment, since the air holes 23 are formed in a region outside the filling material 4 that spreads concentrically and is closer to the center than the apex (corner) of the pile head (protrusion) 31, it is difficult to form an unfilled portion. That is, since the air holes 23 are formed at positions where it is difficult for the filling material 4 to wrap around, by confirming the outflow of the filling material 4 from the air holes 23, it is possible to prevent the formation of unfilled portions (air pockets).

[0016] The present invention is not limited to the above-described embodiments, and each of the above-described components can be appropriately changed without departing from the spirit of the present invention. For example, although the above embodiment described the case of joining a footing 2 and a pile 3, the object to which the joint structure 1 of the present invention can be constructed is not limited to pile foundation structures, but can also be applied to joint structures between other concrete members. For example, it may be used to join precast column members in the construction of columns using precast members. Furthermore, in the above embodiment, the injection holes 22 and air holes 23 were formed so as to extend from the side surface of the footing 2 to the recess 21, but the injection holes 22 and air holes 23 may also be formed so as to extend from the top surface of the footing 2 to the recess 21. Furthermore, the location of the air vents 23 is not limited to being on the inside of the periphery of the pile head 31 and opening directly above the region outside the circle inscribed in the periphery of the pile head 31. It is preferable to provide the air vents 23 within a rectangular region with the line connecting point P and point A as its diagonal. The protrusion of the lower concrete member that is inserted into the recess 21 of the upper concrete is not limited to a cap member, but may also be a projection formed on the upper surface of the lower concrete member. The cap member 32 may be provided as needed. Furthermore, the lower surface of the cap member 32 does not necessarily need to have a frustoconical recess; for example, a columnar recess may be formed. [Explanation of Symbols]

[0017] 1 Joint structure 2. Footing (Upper concrete member) 21 Recess 22 Injection hole 23 air vents 3. Piles (lower concrete members) 31. Pile head (protruding part) 32 Cap component (protruding part) 33 areas 4 Filling material 5 Floor-mounted surface C yen E rectangle G Ground GL ground surface L straight line T-groove (gap)

Claims

1. A joining structure that connects an upper concrete member located on the upper side and a lower concrete member located on the lower side, A square-shaped recess in plan view is formed on the lower surface of the upper concrete member, A single injection hole extending from the side or top surface of the upper concrete member to the center of the recess, Multiple air holes extending from the side or top surface of the upper concrete member to the recess, A square-shaped protrusion in plan view is inserted into the recess formed on the upper part of the lower concrete member, The system comprises a filler material that is filled into the gap between the recess and the protrusion through the injection hole, The joint structure is characterized in that the air vent is located inside the periphery of the protrusion and is open directly above the region outside the circle inscribed in the periphery of the protrusion.

2. Let P be the vertex of the square in plan view of the convex portion, and let A be the intersection of the line connecting the center O of the convex portion and point P, and the circle inscribed on the periphery of the convex portion. The joining structure according to claim 1, characterized in that the air vent is provided within a rectangular region whose diagonal is the straight line connecting point P and point A.

3. A joining structure for joining an upper concrete member disposed on the upper side and a lower concrete member disposed on the lower side, A square-shaped recess in plan view is formed on the lower surface of the upper concrete member, An injection hole extending from the side or top surface of the upper concrete member to the center of the recess, Multiple air holes extending from the side or top surface of the upper concrete member to the recess, A square-shaped protrusion in plan view is inserted into the recess formed on the upper part of the lower concrete member, The system comprises a filler material that is filled into the gap between the recess and the protrusion through the injection hole, The air vent is located on the inner side of the periphery of the protrusion and directly above the region outside the circle inscribed within the periphery of the protrusion. A joining structure characterized in that, when point P is the vertex of the square in plan view of the protrusion, and point A is the intersection of the line connecting the center O of the protrusion and point P with a circle inscribed on the periphery of the protrusion, the air hole is provided within a rectangular region with the line connecting point P and point A as its diagonal, and is located near point B, which is the midpoint between point P and point A.

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