JP2014025309A - Construction method for new foundation, and temporary support plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction method for a new foundation that hardly causes a material loss.SOLUTION: A construction method for a new foundation includes: an excavation step of excavating ground under an existing foundation 1 to a leveling work surface 2 of the new foundation 40; an installation step of installing a temporary support plate 10 on the leveling work surface 2 and installing a temporary support column 20 and an expansion jack 30 on the temporary support plate 10; a press-in step of pushing a frame-like rib plate 12, which is formed on the undersurface of the temporary support plate 10, into the leveling work surface 2 by extending the expansion jack 30; and a foundation new-construction step of constructing the new foundation 40 in the state of supporting the existing foundation 1 by the temporary support plate 10, the temporary support column 20 and the expansion jack 30.

Description

  The present invention relates to a new foundation construction method and a temporary support plate.

In seismic isolation work that installs a seismic isolation device at the bottom of an existing building, after excavating the lower part of the existing building to form a work space, a new foundation is formed, and the space between this new foundation and the existing foundation The seismic isolation device is installed between the new foundation and the existing foundation in a state where the temporary support is attached and the existing foundation is temporarily supported (for example, see Patent Document 1).
By the way, when the ground strength is high (when a solid foundation is employed or when the number of piles is small), as shown in FIG. In some cases, the new foundation 101 is constructed after temporarily supporting the existing foundation 100 with the support bundle 111 formed by assembling 110 or the like in a cross-beam shape.

JP-A-9-302703

  In the above-described configuration, when a new foundation is constructed below the existing foundation, the support bundle 111 is buried, but since the support bundle 111 uses a lot of H-shaped steel, There was a problem of increased loss.

  This invention solves the said problem, and makes it a subject to provide the construction method and temporary support plate of a new foundation with little material loss.

  In order to solve the above-mentioned problem, the invention according to claim 1 includes an excavation process for excavating the ground under the existing foundation to the flooring surface of the new foundation, and a temporary support plate is installed on the flooring surface. An installation step of installing a temporary support column and a telescopic jack on the temporary support plate, and extending the telescopic jack to push a frame-shaped rib plate formed on the lower surface of the temporary support plate into the flooring surface A new foundation construction method comprising: a press-fitting step; and a foundation new construction step for constructing a new foundation in a state where the existing foundation is supported by the temporary support plate, the temporary support pillar, and the telescopic jack. It is.

  According to such a method, since a fixed installation area can be secured with the temporary support plate, the support force of the existing foundation can be held on the flooring surface. Moreover, since only the temporary support plate and the lower part of the temporary support pillar need be buried in the new foundation, material loss can be reduced as compared with the conventional support bundle.

  The invention which concerns on Claim 2 is a temporary support plate installed in the flooring surface formed by excavating the ground under the existing foundation, Comprising: The top plate part and the rib plate suspended from the lower surface of the said top plate part And a temporary support plate.

  According to such a temporary support plate, since the rib plate bites into the support ground and can be reliably grounded with the ground, the temporary support pillar installed on the temporary support plate can be stably supported. . Further, by providing the temporary support pillar on the temporary support plate, the backfilling member can be made smaller and the material loss can be reduced.

  The invention according to claim 3 is characterized in that the top plate portion has a square shape, and a temporary support column is welded to an intersection of diagonal lines of the top plate portion. According to such a configuration, since the temporary support plate and the temporary support pillar are connected in advance and integrated, the installation work is completed simply by installing the temporary support plate on the flooring surface.

  According to the present invention, it is possible to provide a method for constructing a new foundation of an existing building and a temporary support plate that are easy to construct and have little material loss.

It is a transverse cross section showing the foundation foundation reinforcement structure constituted by the construction method of the new foundation concerning the embodiment of the present invention. It is the figure which showed the temporary support plate which concerns on embodiment of this invention, Comprising: (a) is a top view, (b) is sectional drawing. (A) And (b) is the cross-sectional view which showed each construction step of the construction method of the new foundation of this embodiment. (A) And (b) is the cross-sectional view which showed each construction step of the construction method of the new foundation of this embodiment. (A) And (b) is the cross-sectional view which showed each construction step of the construction method of the new foundation of this embodiment. It is the cross-sectional view which showed the conventional temporary support structure under a foundation.

  As shown in FIG. 1, a temporary support plate 10 according to an embodiment of the present invention is a structural material installed on a flooring surface 2 formed by excavating the ground below an existing foundation 1. On the temporary support plate 10, a temporary support column 20 and an extendable jack 30 are provided.

  As shown in FIG. 2, the temporary support plate 10 includes a top plate portion 11 and a rib plate 12. The top plate portion 11 has a square shape in plan view. The top plate portion 11 is made of a steel plate material. The top plate 11 is formed to a thickness that can maintain strength. A plurality of through holes 14 are formed in the top plate portion 11 for filling a space 13 (see FIG. 2) surrounded by the top plate portion 11 and the rib plate 12 with a filler. In the present embodiment, the filler is mortar M1 (see FIG. 1). A plurality of spaces 13 are formed, and the through holes 14 are formed for each space 13. Note that the through hole 14 at the position where the temporary support pillar 20 is provided is formed to be offset so as not to interfere with the temporary support pillar 20.

  The rib plate 12 is made of a steel plate material. The rib plate 12 is suspended from the lower surface of the top plate portion 11. The rib plate 12 serves as a reinforcing rib that reinforces the temporary support plate 10. The lower part of the rib plate 12 bites into the ground of the flooring surface 2. The rib plate 12 includes an outer frame portion 15 and an inner frame portion 16. The outer frame portion 15 is provided to hang from the peripheral edge portion of the top plate portion 11. The outer frame portion 15 is formed in a cylindrical shape having a square cross section. The upper end portion of the outer frame portion 15 is closed by the top plate portion 11. The lower end portion of the outer frame portion 15 is open. The inner frame portion 16 divides the space inside the outer frame portion 15 into a plurality of spaces 13. The inner frame portion 16 is assembled in a lattice shape inside the outer frame portion 15.

  The temporary support column 20 is made of, for example, an H-section steel. The temporary support column 20 is welded and fixed to the upper surface of the temporary support plate 10 (the upper surface of the top plate portion 11). The center of gravity of the cross section of the temporary support pillar 20 (the center of the web 21a) is disposed at the center of the top plate 11, that is, at the intersection of diagonal lines. The flange 21 b of the temporary support pillar 20 is disposed above the inner frame portion 16. In addition, the temporary support pillar 20 is not limited to H-section steel, For example, the thing of other shapes, such as a round steel pipe, a square steel pipe, and I-shaped steel, may be sufficient.

  As shown in FIG. 1, the temporary support column 20 has a height dimension slightly larger than the height dimension of the new foundation 40 constructed on the flooring surface 2. That is, when the new foundation 40 is constructed, the upper end portion of the temporary support column 20 protrudes from the upper end surface of the new foundation 40.

  The telescopic jack 30 stretches between the floor mounting surface 2 and the existing foundation 1 by expanding and contracting in the vertical direction and extending. The telescopic jack 30 is a hydraulic jack with a screw. Note that the type of jack is not limited to a threaded hydraulic jack. The telescopic jack 30 is fixed on the temporary support column 20 via the adjustment piece 3a. The adjustment piece 3a is a member that adjusts the height, and is made of a box-shaped steel material. The temporary support column 20 and the adjustment piece 3a are fixed by bolts and nuts (not shown). The adjustment piece 3a and the expansion jack 30 are also fixed by bolts and nuts (not shown). An adjustment piece 3 b is also provided on the telescopic jack 30. The adjustment piece 3b has the same shape as the adjustment piece 3a. The upper end of the extension jack 30 and the adjustment piece 3b are also fixed by bolts and nuts (not shown). Non-shrink mortar M2 is laid on the upper surface of the adjustment piece 3b at the upper end to enhance the adhesion with the bottom surface of the existing foundation 1.

  Next, a method for constructing a new foundation using the temporary support plate 10 having the above configuration will be described. In the present embodiment, an example in which the construction method of the new foundation is applied to a seismic isolation work in which a seismic isolation device is installed below the existing foundation 1 will be described.

  The construction method of the new foundation according to the present embodiment includes an excavation process, an installation process, a press-fitting process, a filling process, an adjustment piece installation process, a non-shrink mortar placing process, a supporting force confirmation process, and a new foundation construction. A process and a telescopic jack collecting process.

  As shown to (a) of FIG. 3, an excavation process is a process of excavating the ground below the existing foundation 1 to the flooring surface 2 of the new foundation 40. In the excavation process, the entire ground below the existing foundation 1 is not excavated together, but the existing foundation 1 is divided into areas that do not fall off and partially excavated. The other parts will be excavated sequentially after the temporary support structure under the foundation is constructed. In the excavation process, the height dimension from the flooring surface 2 to the bottom surface of the existing foundation 1 is larger than the sum of the height dimension of the new foundation 40 and the height dimension of the seismic isolation device (not shown). Excavate.

  A recess 2a is formed in the floor mounting surface 2 at a portion where the temporary support plate 10 is installed. The outer shape of the recess 2 a has a square shape that is slightly larger than the planar shape of the temporary support plate 10. The depth of the recess 2 a is approximately twice the size of the top plate 11 of the temporary support plate 10. The peripheral edge of the recess 2a is a slope 2b that is inclined obliquely (see FIG. 1).

  As shown in FIG. 3B, the installation process is a process of installing the temporary support plate 10 to which the expansion jack 30 and the temporary support pillar 20 are connected on the flooring surface 2. In the present embodiment, prior to the installation step, the temporary support body 20 and the extension jack 30 are fixed in advance on the temporary support plate 10 to form the temporary support body 5 (this step is referred to as a “preparation step”). ). In the installation process, the work is performed in a state where the expansion jack 30 is degenerated. The temporary support plate 10 is placed on the surface of the recess 2a.

  In the preparation step, only the temporary support plate 10 and the temporary support column 20 are welded, and after the temporary support plate 10 and the temporary support column 20 are installed on the flooring surface 2, the expansion jack 30 is attached to the temporary support plate 10. You may make it fix on.

As shown in FIG. 4A, in the press-fitting process, the extension jack 30 on the temporary support column 20 is extended, and the rib plate 12 (the outer frame portion 15 and the inner frame portion 16) of the temporary support plate 10 is moved. This is a step of pushing into the flooring surface 2. When the telescopic jack 30 is extended, the existing foundation 1 becomes a reaction force receiver, the temporary support pillar 20 and the temporary support plate 10 are pressed downward, and the rib plate 12 is pressed into the ground. In the press-fitting step, the rib plate 12 is pushed into the ground until the upper surface of the temporary support plate 10 becomes the same height as the flooring surface 2. At this time, earth and sand of the ground below the recess 2a enter the space 13 partitioned by the rib plate 12, but the top plate portion 11 does not reach the bottom surface of the recess 2a, so the top plate of the temporary support plate 10 A gap 17 is formed between the lower surface of the portion 11 and the bottom surface of the recess 2a.
In addition, in the press-fitting process, when sufficient support force can be obtained by grounding the top plate portion 11 to the ground, the rib plate 12 is press-fitted until the top plate portion 11 touches the ground, and the following filling step is performed. Sometimes omitted.

  As shown in FIG. 4B, the filling step is a step of filling mortar (filler) M <b> 1 into the inside of the rib plate 12 from the through hole 14 of the top plate portion 11 of the temporary support plate 10. In the mortar filling step, the mortar M1 is filled from the upper through hole 14 for each gap 17 of each space 13. The mortar M1 is filled until the mortar overflows from the through hole 14, and is filled from the surface of the recess 2a to the lower surface of the top plate portion 11 without a gap. Thereafter, curing is performed for a predetermined time until the mortar M1 develops a predetermined strength.

  By filling the gap 17 with the mortar M1, the unevenness on the bottom surface of the recess 2a can be covered. As a result, the load acting on the temporary support plate 10 can be transmitted from the entire lower surface of the top plate 11 to the entire bottom surface of the recess 2a through the mortar layer. Thereby, stable support can be performed without local concentration of load.

  As shown to (a) of FIG. 5, an adjustment piece installation process is a process of installing the adjustment piece 3b in the upper part of the expansion-contraction jack 30. As shown in FIG. In the adjustment piece installation step, first, the expansion jack 30 is retracted to secure an installation space for the adjustment piece 3b between the existing base 1 and the adjustment piece 3b. Then, the adjustment piece 3b is installed on the expansion-contraction jack 30, and it fixes with a volt | bolt nut.

  The non-shrinking mortar placing step is a step of placing the non-shrinking mortar M2 in the gap between the adjustment piece 3b and the existing foundation 1. In the non-shrinking mortar placing step, the expansion jack 30 is retracted to secure a space for placing the non-shrinking mortar M2 between the existing foundation 1. Then, a mold (not shown) is placed on the adjustment piece 3b, and the non-shrink mortar M2 is placed. Thereafter, curing is performed for a predetermined time until the non-shrinkable mortar M2 exhibits a predetermined strength.

The support force confirmation step is a step of confirming that the temporary support plate 10 is stable (support force is generated on the ground) by extending the expansion jack 30. When the telescopic jack 30 is extended, the temporary support plate 10, the temporary support column 20, and the telescopic jack 30 are stretched between the existing foundation 1 and the flooring surface 2, and the bottom of the recess 2a is pressed. Here, it is confirmed that the ground of the recess 2a is stable and the temporary support plate 10 is stable. At this time, the extension jack 30 is extended so that the pressing force is detected from the hydraulic gauge of the extension jack 30 and the support force can be confirmed to be a predetermined value. Thereby, the supporting force of the existing foundation 1 in the ground can be accurately grasped.
The temporary support 5 formed by the above steps is installed in a predetermined number by sequentially digging down the existing foundation 1.

  As shown in FIG. 5 (b), in the foundation new installation process, the new foundation 40 is constructed in a state where the existing foundation 1 is fully excavated and supported by a plurality of temporary supports 5 under the existing foundation 1. It is a process. The new foundation 40 is a foundation that is newly constructed on the flooring surface 2 and is a part in which a seismic isolation device, a jack device for correcting uneven settlement, and the like are installed (in this embodiment, a seismic isolation device). Install). In the foundation new installation process, concrete is placed after placing the formwork and placing the reinforcement. The new foundation 40 is constructed so that the position slightly lower than the upper end of the temporary support column 20 is the upper end. Thereafter, curing is performed for a predetermined time until the new foundation 40 develops a predetermined strength.

  In this embodiment, a seismic isolation device installation process is provided after the foundation new installation process. The seismic isolation device installation step is a step of installing a seismic isolation device (not shown) between the new foundation 40 and the existing foundation 1. The seismic isolation device is installed at a position suitable for seismic isolation of an existing building at a position where it does not interfere with the temporary support column 20 and the extension jack 30.

  The telescopic jack collecting step is a step of jacking down and collecting the telescopic jack 30 after installing the seismic isolation device between the existing foundation 1 and the new foundation 40. Although not shown in the drawings, in the extension jack collecting step, first, the extension jack 30 is jacked down and the building load is transferred to the seismic isolation device. Thereafter, the bolts and nuts fixing the adjustment piece 3a connected to the temporary support column 20 are loosened, and the adjustment piece 3a and the expansion jack 30, the adjustment piece 3b and the non-shrink mortar thereon are integrally removed.

  The adjustment piece 3a, the adjustment piece 3b, and the non-shrink mortar are removed from the collected members, the expansion jack 30 is taken out, and the expansion jack 30 is reused in another installation place or another construction site. The temporary support plate 10 and the temporary support pillar 20 are buried in the concrete of the new foundation 40.

  According to the construction method of the new foundation and the temporary support plate 10 as described above, as shown in FIGS. 1 and 2, the temporary support plate 10 spreads in a planar shape, so that a fixed installation area can be secured and stable. Can be secured. Further, the strength of the temporary support plate 10 is secured by the rib plate 12. Furthermore, since the ground can be grounded by filling the rib plate 12 with mortar, the load of the existing foundation 1 is applied to the bottom surface of the recess 2a (the floor mounting surface 2 where the temporary support plate 10 is installed). Can be retained. Therefore, since the existing foundation 1 can be supported with a simple structure as compared with the conventional structure (the support bundle 111 in FIG. 6), the construction becomes easy and the construction cost can be reduced.

  Furthermore, the temporary support plate 10, the temporary support pillar 20, and the expansion jack 30 are connected in advance and integrated in the preparation process to form the temporary support body 5. In the installation process, the temporary support plate 10 is attached to the flooring surface 2. The installation work is completed simply by installing, so the labor of the installation process can be reduced.

  Further, since only the temporary support plate 10 and the temporary support pillar 20 are buried in the new foundation 40, material loss can be greatly reduced as compared with the conventional support bundle 111. Furthermore, since the expansion jack 30 can be collected and reused, the construction cost can be further reduced.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not the meaning limited to the said embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably. For example, in the embodiment, the temporary support plate 10 is square in plan view, but may be other shapes such as a circle and a polygon. Moreover, the arrangement shape of the rib plate 12 is not limited to the lattice shape, and the rib plate 12 may be arranged in one direction or may be arranged in a regular triangle shape.

  Moreover, although the case where the construction method of the new foundation was applied to the seismic isolation work was taken as an example in the above embodiment, it can also be applied to constructions other than the seismic isolation work. For example, it can also be applied to repair work for uneven settlement. In this repair work, after temporarily supporting the existing foundation, the jack is installed on the new foundation to return the existing foundation to a horizontal position, and a support column for supporting the existing foundation is separately provided and fixed on the new foundation.

DESCRIPTION OF SYMBOLS 1 Existing foundation 2 Floor mounting surface 10 Temporary support plate 11 Top plate part 12 Rib plate 14 Through-hole 20 Temporary support pillar 30 Telescopic jack 40 New foundation M1 mortar (filler)

Claims (3)

An excavation process for excavating the ground under the existing foundation to the flooring surface of the new foundation;
An installation step of installing a temporary support plate on the flooring surface, and installing a temporary support column and an extension jack on the temporary support plate;
A press-fitting step of extending the telescopic jack and pushing a frame-shaped rib plate formed on the lower surface of the temporary support plate into the flooring surface;
A foundation construction process for constructing a new foundation in a state in which the existing foundation is supported by the temporary support plate, the temporary support pillar, and the telescopic jack. It is a temporary support plate installed on the flooring surface formed by excavating the ground under the existing foundation,
A temporary support plate comprising: a top plate portion; and a rib plate hanging from the lower surface of the top plate portion. The top plate has a square shape,
The temporary support plate according to claim 2, wherein a temporary support column is welded to an intersection of diagonal lines of the top plate portion.

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