JP2002115260A - Extension method for basement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for enabling the inexpensive short-term extension of a basement while reducing the generation of noise, vibration, dust, concrete fragments, etc. SOLUTION: In a pile foundation-type structure, a cut-off earth retaining wall 7 is formed under an underground exterior wall 1, which is the remainder of an existing building, an earth retaining pile inserting hole is dug from the inside of the exterior wall 1 in the footing beam 3A of a batholith 3 and the wall 7 so as to install an earth retaining pile 8, and the existing building is supported by a plurality of foundation piles 9. When a bottom surface 6 to be excavated is located in a relatively shallow position, most of the batholith 3 except the section of the footing beam 3A, which is supported by the foundation piles 9, is demolished for removal. Excavation is carried out from the demolished and removed section to as deep a position as the bottom surface 6 for he purpose of enlarging an underground space (When the bottom surface 6 is located in a deep position, the pile 8 is supported by timbering), wherein a new batholith 5, a second-basement floor 4 comprising the footing beam 3A and a new underground external wall 1A disposed inside the pile 8 are constructed, and the unnecessary foundation piles 9 are removed so as to extend a third basement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for expanding a basement floor under an existing building.

[0002]

2. Description of the Related Art In urban areas such as city centers where land prices are high, the number of people who wish to expand the basement floor in addition to the ground floor when rebuilding a building has increased in recent years. In response to such demands, all existing basement floors were conventionally dismantled and removed, backfilled with earth and sand, etc., and vacant land was rebuilt. Excavation and construction of the underground structure were carried out in the same procedure.

[0003]

However, according to the above-mentioned conventional construction method, noise, vibration, and noise are generated when the existing basement floor is dismantled.
Dust is generated, industrial waste (concrete waste) is generated due to the dismantling of the existing basement floor, and construction work such as arranging, compacting, compacting, etc. of backfill soil that will be dug up immediately is required. There were problems such as an increase in the construction period and a significant increase in the construction period, and an increase in earth pressure due to disturbance of the in-situ ground due to the demolition of the existing basement floor. there were.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and a first invention is a mountain retaining wall provided with a waterproof property below an underground outer wall of an existing building. Forming a pile, and arranging a pile on the inside of the retaining wall or inside the retaining wall, and when the existing building has a pile foundation, remove the bottom except for the foundation beam connected to the foundation pile. Demolition and removal, when the existing building is a direct foundation without foundation piles, cast a temporary foundation pile, dismantle and remove the bottom except for the temporary foundation pile, excavate from the removed bottom part, and basement floor This is a basement floor extension method characterized by forming an extension space and adding a basement floor to that part.

According to a second aspect of the present invention, there is provided a method of extending an underground floor according to the first aspect, wherein the excavation is carried out by supporting a pile retaining pile with a support.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. In this case, as shown in FIG. 6, this is an example in which a third basement is added below a second basement.

[First Embodiment] A first embodiment of the present invention will be described with reference to FIGS. The underground floor extension method according to the first embodiment is effective when an underground floor having a relatively low ceiling is further extended below the underground floor (for example, the second basement floor) of an existing building whose top floor has been demolished. It is.

As shown in FIG. 1 (B) and the like, a mountain retaining wall 7 having waterproofness is provided under the underground outer wall 1 left by the existing building.
To form The mountain retaining wall 7 is formed at an appropriate interval (for example, _m interval) on the underground outer wall 1 itself or on the outside of the underground outer wall 1 from an improving agent injection hole (not shown) having a depth at the lower end of the underground outer wall 1. For example, a ground improvement agent (hardening agent) such as cement or mortar is injected to a position deeper than the planned bottom 6 to be excavated by a method such as high-pressure jet grout, and is hardened to form below the underground outer wall 1 and wider than the underground outer wall 1. I do. The ground improvement agent may be inserted and installed in a later step, for example, at a portion deeper than the lower end of the mountain retaining pile 8 made of H-shaped steel, the width thereof may be narrowed and injected.

[0009] Then, from just inside the underground outer wall 1, a pier pile insertion hole having a depth exceeding the planned excavation bottom surface 6 is formed in the foundation beam 3A of the bottom 3 of the existing building and the reinforced wall 7 formed below the foundation beam 3A. Digging, there is a retaining pile 8 made of, for example, H-section steel
And the gap is filled with soil mortar (not shown) to fix the mountain retaining pile 8 to the mountain retaining wall 7.

[0010] The connection between the retaining pile 8 and the foundation beam 3 is as follows.
For example, this is performed as shown in FIG.

When the existing building to be added is a pile foundation type structure supported by a plurality of foundation piles 9 and the planned bottom 6 to be excavated is relatively shallow, the foundation beam 3A supported by the foundation piles 9 is formed. Most of the bottom 3 is dismantled and removed, leaving the part, and the underground space is expanded by immediately excavating from that part to the depth of the bottom 6 to be excavated. A second basement floor 4 including beams 3A,
New underground outer wall 1 placed inside H-shaped steel retaining pile 8
In addition to building A, unnecessary foundation piles 9 are removed and the third basement floor is expanded (see FIG. 2).

Further, when the existing building to be added is a direct foundation type structure which is not supported by the foundation pile 9 and the bottom surface 6 to be excavated is relatively shallow, as shown in FIG. After placing the pile 9A, most of the bottom plate 3 is dismantled and removed, excluding the portion of the foundation beam 3A supported by the temporary foundation pile A9, and excavation is immediately performed from the portion to the depth of the planned bottom 6 to be excavated. The space is expanded, and a bottom plate 5 and a second basement floor 4 including a foundation beam 3A are newly added thereto as in FIG.
And a new underground outer wall 1A to build a third basement floor (the retaining pile 8 is provided immediately inside the retaining wall 7 in this case).

[Second Embodiment] A second embodiment of the present invention will be described with reference to FIG. The basement floor extension method according to the second embodiment is an effective extension method when an underground floor with an even higher ceiling is added below the basement floor (for example, the second basement floor) of an existing building whose top floor has been demolished. .

When the third basement floor with a high ceiling is added below the second basement floor, the position of the bottom surface 6 to be excavated is deepened, so that the excavation pile 8 has a longer portion exposed by excavation and is easily bent. Therefore, as shown in FIG. 5 (A), for example, as shown in FIG. 5 (A), a pier pile 8 provided immediately inside the pier wall 7 is excavated while being supported and reinforced by a ring supporter 10 suspended from the second basement floor 4. As shown in FIG. 5B, the excavation is performed while being supported and reinforced by the diagonally cut beam 11, and as shown in FIG. 5C, the excavation is performed while being supported and reinforced by the cut beam 12 of the island construction method. Do not bend to the basement side during construction.

As shown in FIG. 5 and the like, after excavation while supporting and reinforcing the pile retaining pile 8, most of the bottom plate 3 is removed except for the portion of the foundation beam 3A supported by the temporary foundation pile 9A (or the foundation 9). Demolition and removal, excavation from that part to the depth of the planned bottom 6 to expand the underground space, using the same method as in the past, the base 5, the second basement floor 4 including the foundation beam 3A, and the pile retaining pile In addition to constructing a new underground outer wall 1A to be disposed inside the base 8 and removing unnecessary temporary foundation piles 9A (or foundation piles 9), the third basement floor is expanded (see FIG. 2).

Since the present invention is not limited to the above embodiment, various modifications can be made without departing from the spirit of the present invention.

For example, a pumping well (hole) may be provided to pump up the groundwater, and the groundwater level may be lowered below the planned bottom surface 6 for drilling. Also, this pumping of groundwater may be performed before injecting the soil conditioner into the ground,
It may be performed after the mountain retaining pile 8 is installed.

After the groundwater is lowered to the existing foundation beam position, a part of the existing floor can be dismantled and the ground under the existing floor can be excavated underwater. After excavation in water, concrete is poured into the bottom, and then the groundwater is lowered to the level of the concrete in the basement to create a basement.

[0019]

As described above, the present invention is a method of expanding an underground floor while leaving most of the underground floor of an existing building. Compared to the conventional method of constructing the basement floor, noise, vibration,
Low dust generation, low generation of industrial waste (concrete waste), no need to arrange backfill soil, compaction, compaction, etc., greatly reducing costs and shortening the construction period There is a remarkable effect that the increase of the earth pressure due to the disturbance of the in-situ ground is small.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a first embodiment, and FIG.
Is a plan view, and (B) is a sectional view.

FIG. 2 is an explanatory diagram showing a basement floor added according to the first embodiment.

FIG. 3 is an explanatory diagram when an extension is performed using a temporary foundation pile in the first embodiment.

FIG. 4 is an explanatory diagram showing a connection point between a foundation beam and a retaining pile according to the first embodiment.

FIG. 5 is an explanatory view showing a second embodiment, and FIG.
Is an illustration in which the retaining pile is supported by a ring support pile,
(B) is an explanatory view in which the retaining pile is supported by diagonally cut beams,
(C) is an explanatory view in which the mountain retaining pile is supported by the cut beam of the island construction method.

FIG. 6 is an explanatory diagram showing an outline of an extension.

[Explanation of symbols]

 Reference Signs List 1 (existing) underground outer wall 1A (new) underground outer wall 2 (existing) 1st floor underground 3 (existing) bottom 3A foundation beam 4 (new) 2nd floor underground 5 (new) bottom 6 Excavated bottom 7 mountain retaining wall 8 retaining Pile 9 Foundation pile 9A Temporary foundation pile 10 Ring support 11 Diagonally cut beam 12 Cut beam of island method

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Miji Asaka 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Corporation F-term (reference) 2D047 AA01 AB08 2E176 AA01 AA07 BB32 BB36

Claims (2)

[Claims] 1. A mountain retaining wall having waterproofness is formed below an underground outer wall of an existing building, and a mountain retaining pile is disposed inside the mountain retaining wall or at a portion inside the mountain retaining wall. When the foundation is provided, the bottom excluding the foundation beam connected to the foundation pile is dismantled and removed, and when the existing building is a direct foundation without foundation pile, the temporary foundation pile is cast and then A basement floor extension method characterized by dismantling and removing the bottom part except for the above-mentioned part, excavating from the removed bottom part part to form an underground floor extension space, and adding an underground floor to that part. 2. The method according to claim 1, wherein the excavation is carried out by supporting the pile retaining pile with a support after the bottom portion is dismantled and removed.