JP5480745B2 - Reinforcement method for existing foundations for structures - Google Patents

Description

  The present invention relates to a method for reinforcing an existing foundation for a structure, in particular, in an existing foundation for a structure having an existing footing constructed on a pile, a steel sheet pile wall is constructed around the existing footing, and the inner side of the steel sheet pile wall A steel pipe pile is driven into the ground in the valley, and the steel sheet pile wall and the steel pipe pile are integrated. A new footing is constructed between the steel sheet pile wall and the existing footing, and the steel sheet pile wall and the steel pipe pile and the existing footing are integrated. It is related with the reinforcement method of the existing foundation for structures which can reinforce an existing foundation firmly.

  Usually, as shown in FIG. 7, the foundation 21 of the structure includes a pile 23 constructed in the ground 22 and a reinforced concrete footing 24 constructed on the pile 23. The construction of the foundation 21 has conventionally had the following background.

  (1) As shown in FIG. 8, the connecting method of the pile 23 and the footing 24 is a method of fixing the anchor reinforcing bar 25 extended from the head of the pile 23 to the concrete of the footing 24, and as shown in FIG. In addition, there is a method of embedding the upper portion of the pile 23 in the footing 24 as it is. In any method, the pile 23 needs to be securely fixed to the footing 24. Therefore, as shown by (L1) in FIG. 8 and FIG. More than 23 radial dimensions (L2) had to be separated.

  (2) Generally, the footing 24 is constructed to a depth of about 0.5 m to 3.0 m from the ground surface. Therefore, the ground 22 for constructing the foundation 21 is excavated wider than the actual dimensions of the footing 24 to be constructed. In general, after installing the outer mold in the hole, concrete is placed in the outer mold and backfilled.

  (3) In designing the foundation 21 described above, the pile 23 has a characteristic that it is superior to the rigidity in the axial direction over the rigidity in the horizontal direction. If the position of the pile 23 is arranged as far as possible from the center of the pier, the rotational rigidity of the foundation 21 can be improved as a whole. That is, if the piles 23 are arranged in this way, the foundation 21 can be rationally and economically constructed.

  (4) Conventionally, a sheet pile foundation method using a steel sheet pile for temporary earth retaining work during ground excavation is known. According to the sheet pile foundation method, the outer formwork of the above (2) can be made unnecessary, so that the excavation area of the ground can be reduced. For example, in Patent Document 1 (Japanese Patent No. 4300166), as shown in FIG. 10, the strength of the foundation 21 is improved by integrating the steel sheet pile wall 26 and the footing 24 with a perforated steel plate 27 or the like. Structural foundations are disclosed. Moreover, in patent document 2 (Unexamined-Japanese-Patent No. 2008-240356), as shown in FIG. 11, the footing 24 by which the bridge pier 28 is built supported by the pile 23, and the ground around the pile 23 are constructed | assembled. There is disclosed a structural foundation in which a pile 23 and a steel sheet pile wall 26 are integrated via a footing 24.

Japanese Patent No. 43001666 JP 2008-240356 A

  For example, when a structure such as a bridge is constructed in a narrow place such as an urban area, the site width of the pier (the site width including the range that can be leased at the time of construction) becomes very narrow. As a result, due to the reasons (1) and (2) above, the construction position of the pile 23 could not be sufficiently separated from the pier center. That is, as shown in FIG. 12, in order to construct the pier 28 in a narrow place, for example, after the pile 23 is constructed in the ground 22, a steel sheet pile is placed in the ground 22 near the boundary of the construction site of the foundation 21. The steel sheet pile wall 26 as a retaining wall is constructed by driving in. Next, after excavating the ground 22 in the steel sheet pile wall 26 to a predetermined depth, an outer space 30 is constructed by providing a work space 29 inside the steel sheet pile wall 26. Next, concrete is placed in the outer mold 30 to construct the footing 24 and backfill. Then, the pier 28 is constructed on the footing 24. The steel sheet pile wall 26 may be removed after the foundation 21 is constructed.

  In this way, the pier 28 is constructed, but since it is necessary to provide a working space 29 inside the steel sheet pile 26, the dimensions of the footing 24 are smaller than the excavation hole. Therefore, for the reason (3) above, the distance (L2) between the center position of the pier 28 and the center position of the pile 23 cannot be separated, and the advantageous axial rigidity of the pile 23 is effectively utilized. I can't. As a result, the rotational rigidity of the foundation 21 cannot be increased as a whole. That is, the foundation 21 cannot be rationally and economically constructed.

  As shown in FIG. 12, this problem can be solved by increasing the horizontal rigidity by increasing the diameter (R2) of the pile 23, but this greatly increases the construction cost.

  In addition, according to the foundation for structures shown in FIG. 10 disclosed in the above-mentioned Patent Document 1, the footing 24 can be constructed up to the boundary of the construction site of the structure, but this foundation 21 uses a pile. Therefore, there is no idea that the pile and the steel sheet pile wall 26 are integrated.

  Further, according to the structural foundation shown in FIG. 11 disclosed in Patent Document 2, the periphery of the pile 23 is surrounded by the steel sheet pile wall 26, and the pile 23 and the steel sheet pile wall 26 are integrated. Although the pile 23 can be reinforced, the foundation for this structure has the center position of the pier 28 and the center position of the pile 23 because the pile 23 is not driven into the ground in the inner valley of the steel sheet pile wall 26. The distance (L2) between the two cannot be separated.

  Accordingly, an object of the present invention is to construct a steel sheet pile wall around an existing footing in an existing foundation for a structure having an existing footing constructed on a pile, and a steel pipe pile on the ground in the inner valley portion of the steel sheet pile wall. The steel sheet pile wall and steel pipe pile are integrated, a new footing is constructed between the steel sheet pile wall and the existing footing, and the existing foundation is constructed by integrating the steel sheet pile wall and steel pipe pile with the existing footing. An object of the present invention is to provide a method for reinforcing an existing foundation for a structure that can be reinforced strongly.

  The present invention is characterized by the following.

  The invention according to claim 1 is a method of reinforcing an existing foundation for a structure including an existing footing constructed on a pile, and a plurality of concavo-convex steel sheet piles are viewed in a plan view around the existing footing. Building a steel sheet pile wall composed of those connected to each other, excavating the ground between the steel sheet pile wall and the existing footing, driving a steel pipe pile into the ground in the inner valley of the steel sheet pile wall, A steel sheet pile wall and the steel pipe pile are integrated by a connecting means, and a new footing is constructed by placing concrete between the steel sheet pile wall and the existing footing, and the steel sheet pile wall and the steel pipe pile and the new construction It is characterized in that the footing is integrated by an integration means.

  Invention of Claim 2 is the reinforcement method of the existing foundation for structures of Claim 1, After constructing the said steel sheet pile wall, it excavates the ground in the said steel sheet pile wall, Then, the said steel pipe Instead of driving a pile, the steel pipe pile is driven, the steel sheet pile wall is constructed, and then the ground in the steel sheet pile wall is excavated.

  Invention of Claim 3 is the construction method of the foundation for structures of Claim 1, After constructing | assembling the said steel sheet pile wall, it excavates the ground in the said steel sheet pile wall, Then, the said steel pipe pile Instead of driving the steel sheet pile, the steel sheet pile wall is constructed, the steel pipe pile is driven, and then the ground in the steel sheet pile wall is excavated.

  Invention of Claim 4 is a reinforcement method of the existing foundation for structures as described in any one of Claim 1 to 3, The said steel pipe pile is a diameter which fits in the said inner trough part of the said steel sheet pile wall. It has the characteristic in having.

  The invention according to claim 5 is characterized in that, in the reinforcing method for an existing foundation for a structure according to any one of claims 1 to 4, the connecting means is made of welding. is there.

  Invention of Claim 6 is a reinforcement method of the existing foundation for structures as described in any one of Claim 1 to 4, The said connection means connects the said steel pipe pile and the said steel sheet pile wall. It is characterized by comprising a connecting member.

  The invention according to claim 7 is the method for reinforcing an existing foundation for a structure according to any one of claims 1 to 6, wherein the integration means is a plurality of pieces fixed to the steel pipe pile. The steel pipe pile and the new footing are characterized by being integrated when the concrete of the new footing enters the opening of the plate material.

  The invention according to claim 8 is the method for reinforcing an existing foundation for a structure according to any one of claims 1 to 6, wherein the integration means includes a plurality of openings formed in the steel pipe pile. The steel pipe pile and the existing footing are characterized in that the concrete of the new footing is integrated by entering into the opening of the steel pipe pile.

According to the present invention, the following effects are brought about.
(1) As a steel sheet pile, for example, a U-shaped steel sheet pile is used, and a steel pipe pile is used as the pile, whereby the pile and the steel sheet pile wall can be firmly integrated.
(2) A steel sheet pile wall is constructed in the ground closest to the site boundary of the construction site of the existing foundation, a steel pipe pile is driven into the ground in the inner valley of the steel sheet pile wall, and the steel sheet pile wall is integrated. By constructing a new footing between the existing footing and the existing footing, the position of the pile can be arranged far away from the center of the structure on the footing. As a result, the advantageous axial rigidity of the pile can be effectively utilized.
(3) Since the advantageous axial rigidity of the pile can be utilized effectively, the diameter of the steel pipe pile can be reduced, and as a result, the cost required for reinforcing the foundation can be reduced.
(4) With the above effects, it is possible to reinforce the existing foundation for structures reasonably and economically.

It is a schematic sectional drawing which shows the existing foundation for structures reinforced by the reinforcement method of this invention. It is the sectional view on the AA line of FIG. It is a front view which shows the integration means of the steel pipe pile and new footing in the reinforcement method of this invention. It is a front view which shows another integrated means of the steel pipe pile and new footing in the reinforcement method of this invention. It is a front view which shows another integration means of the steel pipe pile and new footing in the reinforcement method of this invention. It is a schematic sectional drawing which shows the reinforcement method of this invention, (a) is a figure which shows the state which constructed the steel sheet pile wall in the ground, (b) excavated the ground between the steel sheet pile wall and the existing footing The figure which shows a state, (c) is a figure which shows the state which nailed the steel pipe pile in the ground in the inner side trough part of a steel sheet pile wall, (d) is concrete placing between the steel sheet pile wall and the existing footing. It is a figure which shows the state which constructed | assembled the new footing. It is a schematic sectional drawing which shows the foundation which consists of a pile and the footing constructed | assembled on the pile. It is a schematic sectional drawing which shows the combined state of a pile and a footing by anchoring the anchor reinforcement extended from the head of the pile to concrete of footing. It is a schematic sectional drawing which shows the combined state of the pile and footing by embedding the upper part of a pile in a footing as it is. It is a schematic sectional drawing which shows the foundation for structures disclosed by patent document 1. It is a schematic sectional drawing which shows the foundation for structures disclosed by patent document 2. FIG. It is a schematic sectional drawing which shows the foundation for structures constructed in the narrow place.

  One embodiment of the method for reinforcing an existing foundation for a structure according to the present invention will be described with reference to the drawings.

  1 is a schematic cross-sectional view showing an existing foundation for a structure reinforced by the reinforcing method of the present invention, FIG. 2 is a cross-sectional view taken along line AA of FIG. 1, and FIGS. 3 to 5 are reinforcing methods of the present invention. It is a front view which shows the integration means of the steel pipe pile and newly installed footing.

  In FIG. 1, reference numeral 1 denotes an existing foundation, which is composed of a pile 3 constructed on the ground 2 and an existing footing 4 constructed on the pile 3. Reference numeral 5 denotes a steel sheet pile wall constructed around the existing footing 4. As shown in FIG. 2, the steel sheet pile wall 5 is composed of a plurality of concave and convex steel sheet piles, for example, U-shaped steel sheet piles 5a connected to each other such that the plan view is corrugated, For example, it is constructed in the ground 2 closest to the site boundary of the bridge pier 6 (indicated by a two-dot chain line in FIGS. 1 and 2). In addition, when the steel sheet pile wall 5 in the case of construction of the existing foundation 1 is not removed, the existing steel sheet pile wall is used as it is.

  Reference numeral 7 denotes a steel pipe pile driven into the ground in the inner valley (C) of the steel sheet pile wall 5. As shown in FIG. 2, the steel pipe pile 7 has a diameter (R1) that fits in the inner valley (C). Thus, by making the diameter (R1) of the steel pipe pile 7 small enough to fit in the inner trough (C) of the steel sheet pile wall 5, the center of the pier 6 on the existing footing 4 will be described later. On the other hand, the position of the steel pipe pile 7 can be arranged far away, and as a result, the advantageous axial rigidity of the steel pipe pile 7 can be effectively utilized. The head portion of the steel pipe pile 7 and the steel sheet pile wall 5 are firmly connected to each other through connecting means described later.

  In addition, in this example, although the diameter (R1) of the steel pipe pile 7 has a dimension of a grade which fits in the inner trough part (C) of the steel sheet pile wall 5, a part of steel pipe pile 7 is a inner trough part ( The dimension may protrude from C).

  As the connection means, since the steel sheet pile wall 5 and the steel pipe pile 7 can be welded, there is means for directly welding them (the welding location is indicated by W in FIG. 2). As shown in FIG. 2, the steel sheet pile wall 5 and the steel pipe pile 7 may be welded via a plate-like connecting member 8. The plate-like connecting members 7 may be provided at intervals along the longitudinal direction of the steel pipe pile 3 or may be provided continuously. In the case where the plate-like connecting member 7 is provided continuously, a closed space (S) is formed by the steel pipe pile 3, the steel sheet pile wall 5 and the plate-like connecting member 8, and therefore, in this closed space (S), If the concrete at the time of constructing the new footing mentioned later is filled, the steel sheet pile wall 5 and the steel pipe pile 7 will be connected more firmly. Of course, a connecting means for directly welding the steel sheet pile wall 5 and the steel pipe pile 7 and a connecting means by the connecting member 7 may be used in combination.

  9 is a new footing constructed between the steel sheet pile wall 5 and the existing footing 4. The steel sheet pile wall 5 and the steel pipe pile 7 and the existing footing 9 are integrated by an integration means. As shown in FIG. 1, the means for integrating the steel sheet pile wall 5 and the existing footing 9 comprises a reinforcing bar 10 fixed between the steel sheet pile wall 5 and the reinforcing reinforcing bar (not shown) of the existing footing 9, and the reinforcing bar 10 is integrated by fixing with the concrete of the new footing 9. The existing footing 4 and the new footing 9 are integrated by means such as arranging reinforcing bars between them.

  As shown in FIG. 3, the means for integrating the steel pipe pile 7 and the new footing 9 includes a reinforcing bar 12 arranged between the steel pipe pile 7 and the reinforcing reinforcing bar (not shown) of the new footing 9. The pile 7 and the new footing 9 are integrated by fixing the reinforcing bar 12 to the concrete of the new footing 9.

  As shown in FIG. 4, the integration means may be a plate material 11 made of a steel plate having a plurality of openings 11 a welded to the steel pipe pile 7 along its longitudinal direction. When the concrete of the new footing 9 enters the opening 11a of the plate member 11, the steel pipe pile 7 and the new footing 9 are integrated.

  The integration means may be a plurality of openings 7a formed in the steel pipe pile 7, as shown in FIG. When the concrete of the new footing 9 enters the opening 7a of the steel pipe pile 7, the steel pipe pile 7 and the new footing 9 are integrated.

  As an integration means, as shown by a two-dot chain line in FIG. 4, the reinforcing bar 13 may be fixed between the opening 11a of the plate 11 and the reinforcing bar (not shown) in the new footing 9. 5, a rebar 14 may be fixed between the opening 7 a of the steel pipe pile 7 and a reinforcing bar (not shown) of the new footing 9 as indicated by a two-dot chain line. Thus, the steel pipe pile 7 and the new footing 9 can be integrated more firmly by arranging the reinforcing bar 13 or the reinforcing bar 14 and fixing it to the concrete of the new footing 9.

  In this way, the steel sheet pile wall 5 is constructed so as to surround the existing footing 4 in the ground 2 near the site boundary of the construction site of the existing foundation 1, and in the ground of the inner trough (C) of the steel sheet pile wall 5. The steel pipe pile 7 is driven in and integrated with the steel sheet pile wall 5, and a new footing 9 is constructed between the steel sheet pile wall 5 and the existing footing 4, and the steel sheet pile wall 5 and the steel pipe pile 7 are integrated with the new footing 9. By doing so, it is possible to add the existing footing 4 to the nearest site boundary, and the steel pipe pile 7 can be arranged far away from the center of the pier 6 on the existing footing 4. That is, in FIG. 1, the distance between the center position of the pier 6 and the center position of the steel pipe pile 7 is indicated by (L1), and the distance between the center position of the pier 6 and the center position of the existing pile 3 is (L2). However, since (L1) is longer than (L2), the advantageous axial rigidity of the steel pipe pile 7 can be effectively utilized.

  Moreover, since the advantageous axial rigidity which the steel pipe pile 7 has can be utilized effectively, the diameter of the steel pipe pile 7 can be made thin, As a result, the cost required for reinforcement of the existing foundation 1 can be reduced. it can. That is, in FIG. 1, although the diameter of the steel pipe pile 7 is shown by (R1) and the diameter of the existing pile 3 is shown by (R2), (R1) is thinner than (R2).

  Due to the above effects, the existing foundation 1 for structures can be reinforced reasonably and economically.

  Next, a method for reinforcing an existing foundation for a structure according to the present invention will be described with reference to the drawings.

  FIG. 6: is a schematic sectional drawing which shows the reinforcement method of this invention, (a) is a figure which shows the state which constructed | assembled the steel sheet pile wall in the ground, (b) is between a steel sheet pile wall and the existing footing. The figure which shows the state which excavated the ground, (c) is a figure which shows the state which driven the steel pipe pile into the ground in the inner side valley part of a steel sheet pile wall, (d) is concrete between a steel sheet pile wall and an existing footing. It is a figure which shows the state which laid and newly constructed the footing.

  First, as shown to Fig.6 (a), the steel sheet pile wall 5 which consists of what connected the some U-shaped steel sheet pile 5a around the existing footing 4 so that a planar view may become a waveform is constructed | assembled.

  Next, the ground 2 between the steel sheet pile wall 5 and the existing footing 4 is excavated as shown in FIG.

  Next, as shown in FIG. 5C, the steel pipe pile 7 is driven into the ground 2 in the inner valley portion (C) of the steel sheet pile wall 5, and the head of the steel pipe pile 7 and the steel sheet pile wall 5 are described above. They are integrated by connecting means.

  Next, as shown in FIG. 2D, a new footing reinforcing bar 10 is arranged between the steel sheet pile wall 5 and the existing footing 4, and concrete is placed to construct a new footing 9. At this time, the existing footing 4 and the new footing 9 are firmly integrated by means such as arranging reinforcing bars (not shown) between them, and the steel sheet pile wall 5 and the steel pipe pile 7 and the new footing 9. Are integrated by the integration means described above.

  In this way, the existing foundation for the structure can be reinforced strongly.

  In the reinforcing example, the steel sheet pile wall 5 is first constructed, then the ground 2 in the steel sheet pile wall 5 is excavated, and then the steel pipe pile 7 is driven. Even if the wall 5 is constructed and then the ground 2 in the steel sheet pile wall 5 is excavated, or after the steel sheet pile wall 5 is constructed, the steel pipe pile 7 is driven, and then the ground 2 in the steel sheet pile wall 5 is You may drill.

  As described above, according to the present invention, as a steel sheet pile, for example, a U-shaped steel sheet pile can be used, and a steel pipe pile can be used as a pile, whereby the pile and the steel sheet pile wall can be firmly integrated. Become. In addition, a steel sheet pile wall is built around the existing footing, a steel pipe pile is driven into the ground in the inner valley of the steel sheet pile wall, the steel sheet pile wall and the steel pipe pile are integrated, and the steel sheet pile wall and the existing footing are It is possible to reinforce the existing foundation reasonably and economically by constructing a new footing and integrating the steel sheet pile wall and steel pipe pile with the existing footing.

1: Existing foundation 2: Ground 3: Pile 4: Existing footing 5: Steel sheet pile wall 5a: Steel sheet pile 6: Bridge pier 7: Steel pipe pile 7a: Opening 8: Plate-like connecting member 9: New footing 10: Reinforcing bar 11: Plate material 11a : Opening 12: Reinforcing bar 13: Reinforcing bar 14: Reinforcing bar 21: Foundation 22: Ground 23: Pile 24: Footing 25: Anchor reinforcing bar 26: Steel sheet pile wall 27: Perforated steel sheet 28: Pier 29: Work space 30: Outer formwork

Claims (8)

In the method of reinforcing an existing foundation for a structure with an existing footing built on a pile,
Around the existing footing, a steel sheet pile wall composed of a plurality of concavo-convex steel sheet piles connected to each other in a plan view is constructed, and the ground between the steel sheet pile wall and the existing footing After excavation, a steel pipe pile is driven into the ground in the inner valley of the steel sheet pile wall, the steel sheet pile wall and the steel pipe pile are integrated by connecting means, and concrete is driven between the steel sheet pile wall and the existing footing. A method for reinforcing an existing foundation for a structure, comprising: constructing a new footing, and integrating the steel sheet pile wall and the steel pipe pile and the new footing by an integration means.   After building the steel sheet pile wall, excavating the ground in the steel sheet pile wall, and then driving the steel pipe pile instead of driving the steel pipe pile, then building the steel sheet pile wall, then the steel The method for reinforcing an existing foundation for a structure according to claim 1, wherein the ground in the sheet pile wall is excavated.   After constructing the steel sheet pile wall, excavating the ground in the steel sheet pile wall, then, instead of driving the steel pipe pile, after constructing the steel sheet pile wall, driving the steel pipe pile, then the steel sheet pile The method for reinforcing an existing foundation for a structure according to claim 1, wherein the ground in the wall is excavated.   The method for reinforcing an existing foundation for a structure according to any one of claims 1 to 3, wherein the steel pipe pile has a diameter that fits in the inner valley portion of the steel sheet pile wall. .   The said connection means consists of welding, The reinforcement method of the existing foundation for structures as described in any one of Claim 1 to 4 characterized by the above-mentioned.   The said connection means consists of a connection member which connects the said steel pipe pile and the said steel sheet pile wall, The reinforcement of the existing foundation for structures as described in any one of Claim 1 to 4 characterized by the above-mentioned. Method.   The integration means comprises a plate material fixed to the steel pipe pile and formed with a plurality of openings, and the steel pipe pile and the new footing are formed by the concrete of the new footing entering the opening of the plate material. The method for reinforcing an existing foundation for a structure according to any one of claims 1 to 6, wherein the foundation is integrated.   The integration means includes a plurality of openings formed in the steel pipe pile, and the steel pipe pile and the existing footing are integrated when the concrete of the new footing enters the opening of the steel pipe pile. The method for reinforcing an existing foundation for a structure according to any one of claims 1 to 6, wherein:

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