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 formed in a lower face of the footing 2; an injection hole 22 extending from the side face of the footing 2 to the center of the recess 21; multiple air holes 23 extending from a side face of the footing 2 to the recess 21; a cap member 32 which is inserted into the recess 21 formed in a pile head 31 of the pile 3; and a filler 4 that is filled from the injection hole 22 into a gap between the recess 21 and the cap member 32. The cap member 32 has an octagonal shape in plan view.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. Precast members are generally 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. 7, 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 portion (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 portion 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. Generally, it was considered that the filling was 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 8(a), reaches the edge of the protrusion 131, and flows down from the edge of the protrusion 131, as shown in Figure 8(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 8(c). On the other hand, the filler material 140 does not necessarily spread across the entire upper surface of the protrusion 131 before flowing down. When the filler material 140 flows down from the edge of the protrusion 131, it is presumed to follow the same route. Therefore, especially when the upper surface of the protrusion 131 is rectangular in plan view, even if the discharge of the filler material 140 from the air hole 123 formed on the edge of the recess 121 is confirmed, there is a risk that unfilled areas may remain near the center of the air hole 123, and there is no easy way to determine when the filler material 140 has been filled into 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 recess 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; a plurality of air holes extending from the side or top surface of the upper concrete member to the recess; a protrusion formed on the upper part of the lower concrete member and inserted into the recess; and a filler material that fills the gap between the recess and the protrusion from the injection hole. The protrusion has five or more corners in a plan view. Furthermore, the recess is Having the same number of corners as the aforementioned protrusions In the case of a polygonal shape in plan view, it is desirable that the air holes open near each corner of the recess. Furthermore, in the case of a circular shape in plan view, it is desirable that the air holes open near the intersection of the extension of the line connecting the planar center of the upper surface of the convex portion and each corner of the convex portion with the circumference of the inner wall of the recess.

[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 convex portion, flows down from each side of the convex portion, 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 convex portion. If the planar shape of the convex portion is a polygon with five or more sides, the filler flows down from more sides than in the case of a quadrilateral, and divides in multiple directions to flow into the gap between the inner wall surface of the recess and the side surface of the convex portion, making it difficult for unfilled areas to form. Furthermore, if the recess has a polygonal shape with the same number of corners as the protrusion, the amount of filler can be minimized, which is therefore rational. [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 the joint structure of the first embodiment, where (a) is a cross-sectional view and (b) is a cross-sectional view AA of (a). [Figure 2] 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 3] This is an explanatory diagram showing the injection status of the filling material in the first embodiment, where (a) is the initial injection stage, (b) is the stage when the filling material has reached all eight 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. [Figure 4] This figure shows the joint structure of the second embodiment, where (a) is a cross-sectional view and (b) is a cross-sectional view of (a) AA. [Figure 5] This is an explanatory diagram of the location of the air vents in the joint structure of the second embodiment. [Figure 6] This is an explanatory diagram showing the injection of filler material into a recess in the second embodiment, where (a) is the initial injection stage, (b) is the stage when the filler material has reached all eight sides of the pile head, and (c) is the state in which the filler material is flowing through the gap between the side surface of the pile head and the inner surface of the recess. [Figure 7] This is a cross-sectional view showing an example of a conventional joint structure. [Figure 8] This diagram illustrates the filling of the filler material within a recess in a conventional joint structure, where (a) is the initial injection stage, (b) is the stage when the filler material has reached all four sides of the pile head, and (c) is the situation when the filler 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] <First Embodiment> In the first embodiment, 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 will be described. Figure 1 shows the joining structure 1 between the footing 2 and the pile 3. In this embodiment, a case will be described 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. As shown in Figures 1(a) and (b), a recess 21 with a regular octagonal shape in plan view is formed on the lower surface of the footing 2. 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 of the footing 2 to the center of the recess 21. The number of air holes 23 are also formed to extend from the side of the footing 2 to the recess 21. Each air hole 23 opens near a corner of the recess 21.

[0010] The upper end (protrusion) of the pile 3 is insertable into the recess 21 and has a regular octagonal 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 cap member 32 that is insertable into the recess 21 and has a regular octagonal shape in plan view. 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.

[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 2 shows the work process for constructing a pile foundation structure. The pile construction process is the process of constructing piles 3, as shown in Figure 2(a). In this embodiment, piles 3 are constructed by pressing cylindrical precast members into the ground G, but the type of pile 3 and the construction method are not limited. The piles 3 are pressed in using a rotary press-in device (not shown). Once the construction of pile 3 is complete, the ground level (GL) around the pile head 31 is excavated to expose the pile head 31, and any unevenness in the ground level (GL) is leveled. However, if the construction of pile 3 is stopped at the point where the pile head 31 is exposed, it is not necessary to excavate the ground level (GL).

[0012] As shown in Fig. 2(b), the pile head treatment step is a step of forming a cap member 32 on the pile head portion 31 of the pile 3. The cap member 32 is formed in a state of covering the pile head portion 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 regular octagon shape in plan view with a size that can be inserted into the recess 21, and a truncated cone-shaped depression into which the pile head portion 31 can be inserted is formed on the bottom surface. After forming the cap member 32, the ground material (crushed stone, earth and sand, etc.) 51 is spread around the lower end portion of the cap member 32 to close the gap between the lower end edge of the cap member 32 and the ground surface GL and temporarily fix the cap member 32. After temporarily fixing the cap member 32, leveling concrete 52 is placed as required.

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

[0014] The joining step is a step of joining the pile head portion 31 and the footing 2. The joining of the pile head portion 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 portion 31) as shown in Fig. 2(c). Along with the injection of the filling material 4, 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 assumed that the recess 21 is filled with the filling material 4, and the injection of the filling material 4 is terminated. Fig. 3 shows the injection state of the filling material 4. As shown in Fig. 3(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. 3(b). When the filling material 4 reaches the edge of the cap member 32, it flows down from the edge (each side) of the cap member 32 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 flowing 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. 3(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 overflowing from the gap (groove T) flows into the region inside the peripheral edge of the upper surface of the cap member 32 (pile head 31) and outside the circle inscribed in the peripheral edge 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] According to the joining structure 1 of the present embodiment, since the planar shape of the pile head 31 (the upper part of the lower concrete member) is octagonal, the filling material 4 is divided in multiple directions and flows into the gap between the inner wall surface of the recess 21 and the side surface of the pile head 31. As a result, it is difficult to form an unfilled portion compared to the case where the planar shape of the upper part of the lower concrete member is square. In addition, since the recess 21 has the same number of corners as the pile head 31 (cap member 32), the amount of the filling material 4 can be minimized, which is reasonable.

[0016] <Second Embodiment> In the second embodiment, as in the first embodiment, in the pile foundation structure, the case of joining the pile head 31 of the pile (lower concrete member) 3 and the precast footing (upper concrete member) 2 will be described. Fig. 4 shows the joining structure 1 of the second embodiment. As shown in Figures 4(a) and (b), a circular 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 of the footing 2 to the center of the recess 21. The number of air holes 23 is also formed to extend from the side of the footing 2 to the recess 21.

[0017] The pile head 31 (protruding portion) of the pile 3 is insertable into the recess 21 and has a regular octagonal 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 is provided with a cap member 32 that has a regular octagonal shape in plan view and is insertable 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 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.

[0018] Figure 5 shows the locations where the air holes 23 are formed. As shown in Figure 5, the air holes 23 are formed in the region along the edge of the recess 21 (the region between the edge (inner wall) of the recess 21 and the edge (outer circumference) of the pile head 31). The air holes 23 open on the extension of the line L that radially connects the planar center O of the upper surface of the pile head 31 (cap member 32) and the corner of the cap member 32, and near the intersection of the circumference of the inner wall of the recess 21 and line L.

[0019] 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. The details of the pile construction process, pile head treatment process, and foundation installation process are the same as those shown in the first embodiment, so a detailed explanation is omitted (see Figure 2).

[0020] The joining process involves joining the pile head 31 to the footing 2. The joining of the pile head 31 to the footing 2 is performed by injecting filler material 4 through injection holes 22 to fill the gap between the recess 21 and the cap member 32 (pile head 31) with filler material 4 (see Figure 2(c)). As the filler material 4 is injected, the air in the gap between the recess 21 and the cap member 32 is exhausted through air holes 23. Once the gap between the recess 21 and the cap member 32 is filled with filler material 4, the filler material 4 is discharged from the air holes 23. Once it is confirmed that the filler material 4 has been discharged from all air holes 23, it is assumed that the recess 21 has been filled with filler material 4, and the injection of filler material 4 is terminated. Figure 6 shows the injection process of the filler material 4. As shown in Figure 6(a), the filler 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 Figure 6(b). When the filler material 4 reaches the edge of the cap member 32, it flows down from the edge (each side) of the cap member 32 into the gap (groove T) between the side surface of the cap member 32 and the inner wall surface of the recess 21. The filler material 4 that has flowed down into the gap (groove T) then 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 Figure 6(c). When the filler material 4 is filled into the gap (groove T) between the inner wall surface of the recess 21 and the side surface of the cap member 32, the filler material 4 that overflows from the gap (groove T) flows into the area inside the upper peripheral edge of the cap member 32 (pile head 31) and the area outside the circle inscribed in the peripheral edge of the cap member 32 (pile head 31), and the inside of the recess 21 is filled with the filler material 4 (see Figure 1).

[0021] According to the joint structure 1 of this embodiment, since the planar shape of the pile head 31 is octagonal, the filler material 4 is divided in multiple directions and flows into the gap between the inner wall surface of the recess 21 and the side surface of the pile head 31. As a result, it is less likely for unfilled areas to form compared to the case where the planar shape of the upper part of the lower concrete member is square.

[0022] The present invention is not limited to the embodiments described above, and each of the above-described components can be modified as appropriate 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. 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. The planar shape of the pile head 31 (cap member 32) is not limited to an octagonal shape, as long as it is a polygonal shape having five or more corners. [Explanation of Symbols]

[0023] 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 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 recess 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 protrusion 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 aforementioned protrusion is a polygonal shape having five or more corners in a plan view, The recess has a polygonal shape with the same number of corners as the convex portion, A joining structure characterized in that the air holes are open near each corner of the recess.

2. 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 recess 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 protrusion 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 aforementioned protrusion is a polygonal shape having five or more corners in a plan view, The recess is circular in shape when viewed from above. A joining structure characterized in that the air vent opens near the intersection point of the extension of the line connecting the planar center of the upper surface of the protrusion and each corner of the protrusion with the circumference of the inner wall of the recess.

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