JPH09287154A - Stabilizing method of ground under existing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent rocking or differential settlement of a tank installed on the ground during an earthquake, by providing netted reinforcements at the outside from the perpendicularly surrounding area right under an existing structure and connecting the reinforcements to the foundation. SOLUTION: A plurality of reinforcements 3 are driven at a position separated by a specified distance from an existing structure 1, in the peripheral ground of the existing structure 1 to form a netted reinforcements 4. In this time, the reinforcements are not only diagonally arranged toward the outside of the structure 1 from the perpendicularly lower direction but also arranged so as to incline against the radial direction of the structure 1. And further, the reinforcements are driven to cross each other. Thereafter, the foundation 7 of the structure 1 is widened to sufficiently cover the upper end 8 of the reinforcements 4, with reinforced concrete and the foundation 7 is connected to the upper end 8 of the reinforcements 4. In this way, even when a horizontal external force acts on the structure 1, a tensile resistant force is brought in the reinforcements 4 to withstand the horizontal force and hence, the shearing deformation of the peripheral ground of the structure 1 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coping with liquefaction during an earthquake by improving the ground on which an existing structure such as a ground tank of a crude oil storage facility is installed.

[0002]

Generally, when the ground supporting the aboveground tank is liquefied during an earthquake, the ground at the center of the aboveground tank tends to be difficult to liquefy due to the holding effect due to the weight of the aboveground tank. In addition to the above pressing effect not acting on the ground, the ground around this peripheral portion tends to be particularly easily deformed by the rotation (rocking) of the ground tank about the horizontal axis. For this reason, as a countermeasure against liquefaction of the ground where existing structures such as above-ground tanks are provided, a highly rigid cylindrical wall that reaches up to a solid support ground layer is formed around the structure. There is a way. However, due to liquefaction or injection of contents into the ground tank during an earthquake, the subsidence of the ground directly under the ground tank is large in the central part of the ground tank and small in the peripheral part, so that the ground tank body may be distorted. On the other hand, there is also a measure to strengthen the ground directly below the ground tank by inserting a rod-shaped reinforcing material into the ground diagonally from the periphery of the ground tank toward the center, but at the peripheral part of the ground tank which is the weakest point during liquefaction. There is a problem that the ground is not strengthened. In view of the above circumstances, the present invention has an object of intensively strengthening the ground around the above-ground tank, which is a weak point, and an object of the present invention is to prevent rocking or uneven settlement of the above-ground tank during an earthquake. To do.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned problems. In the ground on which an existing structure is provided, the ground structure is arranged so as to surround the existing structure and extends from the vertically downward direction toward the outside. To provide a method for strengthening an existing structure base plate, which is characterized in that a reticulated reinforcing material is provided, and the upper end of the reinforced reinforcing material is connected to the foundation of the existing structure. is there. As described above, in the present invention, the braided reinforcing bar is provided from the vertically downward direction toward the outside in the arrangement surrounding the existing braided structure, and the braided braided reinforcing bar is connected to the foundation part, so that the existing structural body during an earthquake On the other hand, even if a horizontal external force that causes rocking is applied, tensile resistance of the rebar reinforcing material occurs, and shear deformation of the surrounding ground is suppressed.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in detail based on the embodiments shown in FIGS. In the figure, 1 is an existing structure such as a ground tank. In the present invention, first, in the ground 2 around the existing structure 1, a route pile or the like is located at a position 2 to 3 m away from the existing structure 1. A plurality of reinforcing bars 3 are driven in. The reinforcing bar 3 is driven obliquely from the vertically downward direction toward the outside of the existing structure, and is inclined so as to incline with respect to the radial direction of the existing structure 1. A net-shaped reinforcing bar reinforcing member 4 is provided so as to intersect with each other, and the reinforcing bar 3 expands the diameter obliquely downward. As shown in FIG. 1, in this example, the reinforcing bars 3 are driven into the outermost side, the innermost side, and the spaces between the outermost side and the innermost side, respectively, and the reticulated reinforcing bar 4 is a triple layer arranged in concentric circles. There is. In the present invention, the reticulated reinforcing bar 4
Can be single, double, and quadruple or more, but is not limited thereto. In the example, the reticulated reinforcing bar material is triple, and in FIG. 2, only the outermost rebar reinforcing material is shown in order to facilitate the illustration.

In FIG. 1, reference numeral 5 denotes a liquefaction layer having a depth at which liquefaction occurs during an earthquake, and the lower end of each rebar material 3 constituting the reticulated reinforcing bar 4 reaches the lower part of the liquefaction layer 5. It is driven to the depth, the lower end of each reinforcing bar, that is,
The lower end 6 of the braided reinforcing bar 4 is a fixing means (not shown).
It is fixed to the ground by. Then, after the braided reinforcing bar 4 is provided, the existing structure 1 is provided on the ground surface side.
The base portion 7 of No. 1 is expanded to a size that covers the upper end 8 of the braided reinforcing bar 4 by reinforced concrete construction, and the base portion 7 and the upper end 8 of the braided reinforcing bar 4 are connected and integrated to construct. Complete. When connecting the expanded base portion 6 and the reticulated reinforcing bar 4, a required tensile force may be applied.

[0006]

As described above, according to the method for strengthening an existing structure underlayer of the present invention, the ground on which the existing structure is provided is arranged so as to surround the existing structure so that the ground is directed outward from the vertically downward direction. It is characterized by providing a braided reinforcing bar, and connecting the upper end of the braided reinforcing bar to the foundation of the existing structure, and a horizontal external force that causes rocking to the existing structure during an earthquake. No matter which direction it is applied, a tensile resistance is generated in the braided reinforcing bar, and the horizontal external force is resisted. Therefore, even in the event of an earthquake, shear deformation of the ground around the existing structure will be suppressed, the ground around the existing structure will be strengthened, and rocking and uneven settlement will not occur. It plays.

[Brief description of drawings]

FIG. 1 is an explanatory side view showing an embodiment of a method for strengthening an existing structure foundation board according to the present invention.

FIG. 2 is an explanatory view showing the reticulated reinforcing bar reinforcing material of the embodiment from obliquely above.

[Explanation of symbols]

 1 ... Existing structure 2 ... Ground 4 ... Reinforcing bar reinforcement 5 ... Liquefied layer 7 ... Foundation

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Yoshiaki Yoshimi, 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Akira Otsuki 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Incorporated (72) Inventor Masayoshi Sato 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Corporation

Claims (1)

[Claims] 1. A ground rebar reinforcing material is provided on the ground where the existing structure is provided so as to surround the existing structure from the vertically downward direction toward the outside, and the upper end of the rebar reinforcing material is provided at the existing structure. A method for strengthening an existing structure baseboard, which is characterized in that it is connected to the foundation of an object.