JP5587725B2 - 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, a steel sheet pile wall is constructed around an existing foundation constructed on a vertical pile, and a slant pile is formed on the ground between the existing foundation and the steel sheet pile wall. It is constructed so as to be in contact with the inner peak of the sheet pile wall, and the existing foundation for the structure can be rationally and economically reinforced by connecting the inclined pile and the inner peak of the steel sheet pile wall. It relates to a reinforcing method.

  In recent years, in preparation for disasters such as earthquakes, construction has been carried out to reinforce existing foundations of structures such as piers. An example of a conventional method for reinforcing an existing foundation for a structure will be described with reference to the drawings.

  FIG. 3 is a plan view showing a conventional reinforcing method, and FIG. 4 is a cross-sectional view taken along line AA of FIG.

  3 and 4, 10 is a vertical pile constructed in the ground 11, 12 is an existing footing as an existing foundation constructed on the vertical pile 10, and 13 is a structure constructed on the existing footing 12. A pier as an object, 14 is an additional footing added to the existing footing 12, 15 is a diagonal pile constructed on the ground 11 below the additional footing 14, and 16 is a formwork for constructing the additional footing 14, Reference numeral 17 denotes a steel sheet pile wall constructed on the ground 11 around the formwork 16.

  The existing footing 12 is reinforced as follows by a conventional method of reinforcing an existing foundation for a structure.

  First, the steel sheet pile wall 17 is constructed in the ground 11 around the existing footing 12. The steel sheet pile wall 17 is constructed by, for example, driving a plurality of U-shaped steel sheet piles into the ground 11 while connecting each other.

  Next, the ground 11 in the steel sheet pile wall 17 is excavated to a predetermined depth, and the slant pile 15 is constructed on the ground 11 in the steel sheet pile wall 17.

  Next, in FIG. 4, the formwork 16 is constructed on the ground 11 at the site boundary indicated by the alternate long and short dash line, and concrete is placed in the space between the existing footing 12 and the formwork 16 to construct the additional footing 14. At this time, the existing footing 12 and the additional footing 14, and the head of the oblique pile 15 and the additional footing 14 are coupled by a reinforcing bar (not shown) or the like. Thereafter, the steel sheet pile wall 17 and the formwork 16 are removed and backfilled.

  In this way, the existing footing 12 is reinforced.

  In addition, an example of the foundation structure which combined the vertical pile and the diagonal pile is disclosed by patent document 1 (Unexamined-Japanese-Patent No. 2006-348526).

  According to this foundation structure, a foundation structure with excellent axial rigidity and horizontal rigidity can be constructed by combining a vertical pile with excellent axial rigidity and a diagonal pile with excellent horizontal rigidity. Can do.

JP 2006-348526 A JP 2008-240356 A

  As described above, according to the conventional method for reinforcing an existing foundation for a structure, the existing foundation can be reinforced so that both axial rigidity and horizontal rigidity are excellent, but there are the following problems.

  (1) As a method of connecting the head of the slant pile 15 and the additional footing 14, as shown in FIGS. 5 and 6, a method of fixing the anchor reinforcing bar 18 extended from the head of the slant pile 15 to the footing 14 is added. There is a method of increasing the angled pile 15 itself and embedding it in the footing 14. FIG. 5 is a plan view showing a joint portion between the oblique pile and the additional footing in the former method, and FIG. 6 is a cross-sectional view taken along line BB in FIG.

  However, in order to reliably add the slant pile 15 to the footing 14, any of the above methods increases the outer edge of the slant pile 15 as shown by (L1) in FIG. Must be sufficiently separated from Usually, this separation distance (L1) is about 250 mm or more than the radius of the inclined pile 5 (when the inclined pile diameter is 500 mm or more).

  Thus, since it is necessary to increase the outer edge of the diagonal pile 15 and to fully separate from the end part of the footing 14, the distance (L2) (refer FIG. 6) between the bridge pier 13 and the diagonal pile 15 cannot be separated largely. . As a result, since the effect of increasing the horizontal rigidity of the slant pile 15 cannot be effectively utilized, the rotational rigidity of the footing after repair cannot be sufficiently increased. In order to increase the horizontal rigidity of the slant pile 15, the pile diameter of the slant pile 15 may be increased, but this entails huge construction costs. For this reason, the existing footing 12 cannot be rationally and economically reinforced.

  (2) It is difficult to integrate the slant pile 15 and the additional footing 14. That is, when the anchor reinforcing bar 18 of the diagonal pile 15 is increased and fixed to the footing 14, it is necessary to arrange the anchor reinforcing bar 18 while avoiding the reinforcing bar 19 arranged in the additional footing 14. Since 18 is arranged diagonally, it is difficult to arrange the bars while avoiding the reinforcing bars 19 arranged in the additional footing 14.

  Therefore, the object of the present invention is to construct a steel sheet pile wall on the ground as close as possible to the site boundary around the existing foundation, construct a steel pipe slant pile so as to contact the inner mountain part of the steel sheet pile wall, By connecting the sheet pile wall and the diagonal pile by welding, etc., and constructing the diagonal pile apart from the site boundary with respect to the structure on the existing foundation, the horizontal rigidity of the diagonal pile is increased. An object of the present invention is to provide a method for reinforcing an existing foundation for a structure, which makes it possible to reduce the diameter of a slant pile and thus reinforce the existing foundation rationally and economically.

  Another object of the present invention is to easily and reliably connect an additional foundation and an inclined pile constructed between the existing foundation and the steel sheet pile wall by joining the steel sheet pile wall and the inclined pile by welding or the like. It is providing the reinforcement method of the existing foundation for structures which can be integrated.

  The present invention has been made to achieve the above object, and is characterized by the following.

  The invention according to claim 1 is a steel sheet pile wall comprising a plurality of concavo-convex steel sheet piles connected to each other so as to have a corrugated plan view on the ground as close as possible to the site boundary around the existing foundation. Then, a steel pipe diagonal pile is constructed so as to contact the inner crest of the steel sheet pile wall on the ground in the steel sheet pile wall, and then the ground between the existing foundation and the steel sheet pile wall is constructed. Excavating, and then connecting the steel sheet pile wall and the slant pile, then adding concrete by placing concrete in the space between the steel sheet pile wall and the existing foundation, and adding the additional foundation And the existing foundation are integrated, and the additional foundation and the head of the inclined pile are integrated.

  The invention according to claim 2 is characterized in that, in the method for reinforcing an existing foundation for structure according to claim 1, the steel sheet pile wall and the oblique pile are fixed by welding.

  Invention of Claim 3 is the reinforcement method of the existing foundation for structures of Claim 1 or 2, Comprising: The said steel sheet pile wall is constructed | assembled in planar view rectangular shape, and the said slant pile is built in the said steel sheet pile wall It is characterized by being built in a square shape on the ground.

  The invention according to claim 4 is the method for reinforcing an existing foundation for a structure according to any one of claims 1 to 3, wherein a steel pipe slant pile is attached to the ground in the steel sheet pile wall. Instead of excavating the ground between the existing foundation and the steel sheet pile wall, after excavating the ground between the existing foundation and the steel sheet pile wall, It is characterized in that a steel pipe slant pile is constructed on the ground in the steel sheet pile wall so as to be in contact with the inner mountain portion of the steel sheet pile wall.

  According to the present invention, the following effects are brought about.

  (1) A steel sheet pile wall is constructed on the ground as close as possible to the site boundary around the existing foundation, and a steel pipe pile pile is constructed so as to contact the inner mountain of the steel sheet pile wall. By connecting them with welding or the like, the slant pile can be constructed with the site boundary fully separated from the structure on the existing foundation, so that the horizontal rigidity of the slant pile can be increased. Therefore, since the diameter of the inclined pile can be reduced accordingly, the existing foundation can be reinforced reasonably and economically.

  (2) By connecting the steel sheet pile wall and the inclined pile by welding or the like, the additional foundation and the inclined pile constructed between the existing foundation and the steel sheet pile wall can be integrated easily and reliably. .

  (3) Since it is possible to reduce the diameter of the inclined pile, it is possible to construct the inclined pile and integrate the inclined pile and the steel sheet pile wall even in a narrow space between the steel sheet pile wall and the existing foundation. it can.

It is a top view which shows the existing foundation for structures reinforced by the reinforcement method of this invention. It is CC sectional view taken on the line of FIG. It is a top view which shows the conventional reinforcement method. FIG. 4 is a sectional view taken along line AA in FIG. 3. It is a top view which shows the coupling | bond part of a diagonal pile and additional footing. FIG. 6 is a sectional view taken along line B-B in FIG. 5.

  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.

  FIG. 1 is a plan view showing an existing foundation for a structure reinforced by the reinforcing method of the present invention, and FIG. 2 is a cross-sectional view taken along the line CC in FIG.

  In FIG. 1 and FIG. 2, 1 is a vertical pile constructed in the ground 2, and 3 is an existing footing as an existing foundation constructed on the vertical pile 1. The existing foundation may be an existing underground beam other than the existing footing 3.

  4 is a pier as a structure constructed on the existing footing 3, and 5 is a steel sheet pile wall constructed in a rectangular shape in plan view on the ground 2 around the existing footing 3. The steel sheet pile wall 5 is composed of, for example, a plurality of U-shaped steel sheet piles connected to each other so as to have a waveform in plan view. In FIG. Has been built. In addition, the reinforcement structure of the foundation which combines a steel sheet pile wall and a vertical pile and makes a steel sheet pile wall bear horizontal rigidity is disclosed by patent document 2 (Unexamined-Japanese-Patent No. 2008-240356).

  6 is a steel pipe slant pile constructed on the ground 2 between the existing footing 3 and the steel sheet pile wall 5. The diagonal piles 6 are constructed in a square shape, two on each of a pair of opposing surfaces of the steel sheet pile wall 5. In addition, the diagonal pile 6 may be constructed | assembled on each surface of the steel sheet pile wall 5, and 1 or 3 or more may be sufficient as it. The diagonal pile 6 is constructed so as to be in contact with the inner mountain portion 5A of the steel sheet pile wall 5, and is coupled to the inner mountain portion 5A by welding or the like. The head of the slant pile 6 is embedded in an additional footing, which will be described later, and is integrated with the additional footing.

  Reference numeral 7 denotes an additional footing constructed between the existing footing 3 and the steel sheet pile wall 5. The existing footing 3 and the additional footing 7 are firmly integrated by a reinforcing bar (not shown) or the like.

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

  First, a plurality of U-shaped steel sheet piles are driven into the ground 2 as close as possible to the site boundary around the existing footing 3 so that the plan view is corrugated, and the rectangular steel sheet pile in plan view Build the wall 5.

  Next, the slant pile 6 is constructed on the ground 2 in the steel sheet pile wall 5 so as to contact the inner mountain portion 5 </ b> A of the steel sheet pile wall 5. The slant pile 6 is constructed at a height at which its head is embedded in an additional footing described later. In addition, the diagonal piles 6 are constructed in a square shape, two on each of a pair of opposing surfaces of the steel sheet pile wall 5. The diagonal pile 6 may be constructed on each surface of the steel sheet pile wall 5 or may be one.

  Next, after excavating the ground 2 between the existing footing 3 and the steel sheet pile wall 5, the inner mountain portion 5 </ b> A of the steel sheet pile wall 5 and the oblique pile 6 are joined by welding or the like.

  In this way, the steel sheet pile wall 5 is constructed on the ground 2 as close as possible to the site boundary, and the slant pile 6 is constructed so as to contact the inner mountain portion 5A of the steel sheet pile wall 5 and joined, thereby existing footing. Since the slant pile 6 can be constructed with the land boundary fully separated from the pier 4 on the top 3, the horizontal rigidity of the slant pile 6 can be increased. Therefore, the diameter of the diagonal pile 6 can be reduced accordingly, and the rotational rigidity of the footing after repair can be sufficiently increased even if the diagonal pile 6 is reduced in diameter. That is, the existing footing 3 can be reinforced reasonably and economically.

  In addition, by joining the inner mountain portion 5A of the steel sheet pile wall 5 and the oblique pile 6 by welding or the like, the later-described additional footing and the oblique pile 6 can be integrated easily and reliably.

  Furthermore, since it becomes possible to reduce the diameter of the slant pile 6, the construction of the slant pile 6 and the integration of the slant pile 6 and the steel sheet pile wall 5 in a narrow space between the steel sheet pile wall 5 and the existing footing 3 are possible. Can be easily achieved.

  When the oblique pile 6 is constructed in this way, concrete is placed in the space between the steel sheet pile wall 5 and the existing footing 3 to increase the number of footings 7. The additional footing 7 and the existing footing 3 are firmly integrated by a reinforcing bar (not shown) or the like. The inclined pile 6 and the additional footing 7 are integrated by increasing the head of the inclined pile 6 and embedding it in the footing 7, but the inclined pile 6 is integrated with the steel sheet pile wall 5 by welding or the like. The slant pile 6 and the additional footing 7 are more firmly integrated.

  In the above example, the ground pile between the existing footing 3 and the steel sheet pile wall 5 is constructed after the slant pile 6 is constructed on the ground 2 in the steel sheet pile wall 5 so as to contact the inner mountain portion 5A of the steel sheet pile wall 5. 2, but after excavating the ground 2 between the existing footing 3 and the steel sheet pile wall 5, the slant pile 6 is placed on the inner pile 5 </ b> A of the steel sheet pile wall 5 on the ground in the steel sheet pile wall 5. You may build so that it may touch.

  As described above, according to the present invention, a steel sheet pile wall is constructed on the ground as close as possible to the site boundary around the existing foundation, and the steel pipe slant pile is in contact with the inner mountain portion of the steel sheet pile wall. By connecting the steel sheet pile wall and the oblique pile by welding or the like, the advantages of the construction method using the oblique pile and the steel sheet pile wall are utilized as they are, and further, the following effects are brought about.

  (1) Since the slant pile can be constructed away from the site boundary with respect to the structure on the existing foundation, the horizontal rigidity of the slant pile can be increased. Therefore, since the diameter of the inclined pile can be reduced accordingly, the existing foundation can be reinforced reasonably and economically.

  (2) By connecting the steel sheet pile wall and the inclined pile by welding or the like, the additional foundation and the inclined pile constructed between the existing foundation and the steel sheet pile wall can be integrated easily and reliably. .

  (3) Since it is possible to reduce the diameter of the inclined pile, it is easy to construct the inclined pile and integrate the inclined pile and the steel sheet pile wall even in a narrow space between the steel sheet pile wall and the existing foundation. be able to.

1: Vertical pile 2: Ground 3: Existing footing 4: Bridge pier 5: Steel sheet pile wall 5A: Inner mountain 6: Diagonal pile 7: Additional footing 10: Vertical pile 11: Ground 12: Existing footing 13: Pier 14: Additional footing 15: Diagonal pile 16: Form 17: Steel sheet pile wall 18: Anchor rebar 19: Rebar

Claims (4)

  A steel sheet pile wall constructed by connecting a plurality of concavo-convex steel sheet piles to each other so as to have a corrugated plan view is constructed on the ground as close as possible to the site boundary around the existing foundation, and then the steel sheet pile A steel pipe slant pile is constructed on the ground in the wall so as to contact the inner mountain portion of the steel sheet pile wall, then excavating the ground between the existing foundation and the steel sheet pile wall, and then the steel sheet pile wall And the slant pile, then, concrete is placed in the space between the steel sheet pile wall and the existing foundation to increase the additional foundation, and the additional foundation and the existing foundation are integrated. And the reinforcement method of the existing foundation for structures characterized by integrating the said additional foundation and the head of the said slanting pile.   The method for reinforcing an existing foundation for a structure according to claim 1, wherein the steel sheet pile wall and the oblique pile are fixed by welding or the like.   The structure according to claim 1 or 2, wherein the steel sheet pile wall is constructed in a rectangular shape in plan view, and the oblique pile is constructed in a square shape on the ground in the steel sheet pile wall. Reinforcement method of existing foundation.   Instead of excavating the ground between the existing foundation and the steel sheet pile wall, instead of excavating the ground between the existing foundation and the steel sheet pile wall after constructing a steel pipe slant pile on the ground in the steel sheet pile wall After excavating the ground between a foundation and the steel sheet pile wall, a steel pipe oblique pile is constructed in contact with the inner mountain portion of the steel sheet pile wall in the ground in the steel sheet pile wall. Item 4. The method for reinforcing an existing foundation for a structure according to any one of Items 1 to 3.

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