JPH09184144A - Construction method for base isolation pit for existing building - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction method capable of reducing the period of construction work and the construction cost. SOLUTION: Ground surrounding an existing building 2 is excavated and a dry area 10 is formed. Also, the earth immediately below the bottom of a structural body of the existing building is excavated for forming an underground space communicating with the lower portion of the dry area 10, and upper portions of existing piles 6 buried in earth from the bottom portion of the structural body are exposed. Then, new piles 34 are buried in the lower ground of the dry area 10. Next, a footing 38 is formed together with new piles 34 in one united body in the lower ground of the dry area 10, and a retaining wall 40 surrounding the side walls of the structural body is built together with the upper portion of a footing 38 in one united body. Next, a pressure- withstanding slab 42 increasing the contact area with underground earth is formed in the underground space. In this case, existing piles 6 are penetrated through the pressure-withstanding slab 42 without connection with the slab. An enlarged diameter portion 46 is formed in one united body around the outer periphery at the top of the existing pile 6 and are contacted with the top surface of the pressure-withstanding slab 42.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing a seismic isolation pit so as to surround a lower part of a body and a side wall of a body of an existing building in a seismic isolation method for an existing building.

[0002]

2. Description of the Related Art In recent years, various seismic isolation construction methods have been developed which have a structure in which the seismic force at the time of earthquake occurrence is not directly transmitted to the building and reduce the shaking of the building as much as possible to prevent the destruction of the building. By the way, in the seismic isolation method of installing a new seismic isolation device in an existing building, a pit is formed so as to surround the lower part of the body of the existing building.

A conventional pit construction method is shown in FIG.
This will be described with reference to FIG. FIG. 10 shows an existing building 2 for which the seismic isolation method is used.
Is supported by a plurality of support piles (hereinafter referred to as existing piles) 6 that reach the support ground 4 from the lower frame body 2a.
When performing the seismic isolation construction method for the existing building 2, first, the mountain retaining wall 8 is embedded so as to surround the side wall 2b of the body of the existing building 2. Then, the soil between the mountain retaining wall 8 and the body side wall 2b is excavated to form the dry area 10, and the body lower portion 2a is formed.
The soil at the bottom is excavated to form an underground space 12 continuous with the dry area 10. And the mountain stop wall 8 of the underground space 12
A new support pile (hereinafter referred to as a new pile) 14 is buried in the underground ground on the side.

Then, as shown in FIG. 11, the footing 1 is integrally formed with the upper part of the new pile 14 at the lower part of the dry area 10.
6 to form the dry area 1 so as to surround the side wall 2b of the body.
The retaining wall 18 is formed in the inside. Then, the pit 22 is constructed by forming the pressure plate 20 integrated with the footing 16 and the existing pile 6 on the underground ground of the underground space 12. And
A seismic isolation device 24 is provided between the upper surface of the pressure plate 20 and the lower body 2a.
After installing, the pile head of the existing pile 6 is cut and the foundation lower part 2
Cut the edge between a and the existing pile 6.

[0005]

By the way, in the pit 22 having the above structure, the new pile 14 buried under the footing 16 supports the weight of the footing 16, the retaining wall 18 and the pressure plate 20. , Earth pressure applied to the retaining wall 18,
Although the structure is such that the water pressure applied to the pressure plate 20 is also supported, the water pressure applied to the pressure plate 20 cannot be reliably supported because the distance L between the new piles 14 is long as shown in FIG. Therefore, the conventional pit 22 has
The thickness dimension T of 0 is set to be large and the heavy pressure plate 20 is constructed to withstand water pressure.

However, if the heavy-duty pressure plate 20 is used, the weight of the existing piles 6 will be increased, and the thickness dimension T of the pressure plate 20 must be increased to form the deep underground space 12 of the underground ground H. I won't. Therefore, since the mountain retaining wall 8 must be buried deeply and a large amount of earth and sand must be excavated, the construction period will be greatly increased. Moreover, a large amount of concrete is required by increasing the wall thickness dimension T of the pressure plate 20. Therefore, it is difficult for the conventional technology to reduce the construction period and the construction cost.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a seismic isolation pit construction method for an existing building which can shorten the construction period and the construction cost. .

[0008]

A method for constructing a seismic isolation pit for an existing building according to claim 1 of the present invention comprises a step of forming a dry area by excavating the ground around the existing building, and a lower part of the skeleton of the existing building. Along with to form an underground space that communicates with the lower part of the dry area by cutting off the ground directly below the skeleton, and exposing the upper part of the existing pile in this underground space,
The step of burying the new pile in the lower ground of the dry area, and forming the footing integrally with the new pile in the lower ground of the dry area, and the retaining wall surrounding the side wall of the skeleton in the dry area to the upper part of the footing. And a step of integrally forming with, in the underground space, cut the edge with the existing pile,
In addition to forming a pressure-resistant plate with an increased contact area with the underground ground, a step of connecting the pressure-resistant plate and the footing, and a diameter-expanded portion integrally formed on the outer periphery of the upper portion of the existing pile, A step of abutting a portion on the upper surface of the pressure-resistant plate to prevent the pressure-resistant plate from rising due to water pressure.

According to a second aspect of the present invention, there is provided a method of constructing a seismic isolation pit for an existing building, which comprises a step of excavating a ground around the existing building to form a dry area, and a step of forming a dry area on the lower part of the structure along the lower part of the structure. Rooting the ground directly below to form an underground space communicating with the lower part of the dry area, exposing the upper part of the existing pile to this underground space, and burying new footing piles in the lower ground of the dry area Together with the step of burying a plurality of new pressure plate new piles at a predetermined interval in the underground ground of the underground space, and forming footings integrally with the new footing piles in the lower ground of the dry area, A step of integrally forming a retaining wall surrounding a side wall of the skeleton in a dry area with the upper part of the footing, and cutting the edge with the existing pile in the underground space and burying the pressure plate in the underground ground To form a pressure-resistant version new pile integral, a construction method that includes a step of connecting the this-voltage version footing.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the pit construction method of the present invention will be described below with reference to the drawings. The same components as those shown in FIGS. 10 and 11 are designated by the same reference numerals, and the description thereof will be omitted. The first embodiment will be described with reference to FIGS. 1 to 8.

First, as shown in FIG. 1, the existing building 2
A mountain stop wall 8 that also serves as a water stop is buried in the soil around the. Then, after the burying of the mountain retaining wall 8 is completed, the existing building 2
The soil between the skeleton side wall 2b and the cliff wall 8 is excavated to form a dry area 10, and a crossbeam 30 is installed between the skeleton side wall 2b and the cliff wall 8. Then, the soil is excavated in the horizontal direction from the bottom of the dry area 18 toward the existing building 2, the root of the existing building 2 is cut directly below the lower part 2a of the existing building 2, and the lower surface of the lower part of the structure 2a is used as a ceiling to extend horizontally. Then, the underground space 32 exposing the upper part of each existing pile 6 is formed. At this time, the underground space 32 is formed so that the depth of the underground ground 32b located below the lower frame body 2a is shallower than that of the underground ground 32a on the mountain retaining wall 8 side.

Then, as shown in FIG. 2, the first new pile 34 made of reinforced concrete is buried in the underground ground 32a on the mountain retaining wall 8 side. In addition, from the first new pile 34 to the underground ground 3
The second new pile 36 of reinforced concrete is buried on the 2b side. Next, the reinforcing bars for footing are laid on the underground ground 32a, the reinforcing bars for the retaining wall are reinforced inside the dry rear 10, and the reinforcing bars for the pressure plate are laid on the underground ground 32b, and then the reinforcing bars for the footing and the retaining wall. By placing concrete on the reinforcing bar, as shown in FIG. 3, a footing 38 integrated with the first new pile 34 and the second new pile 36 is formed on the underground soil 32a, and a retaining wall 40 is formed in the dry area 10. Form. Then, after the footing 38 and the retaining wall 40 are completely solidified,
Concrete is placed on the reinforcing bar for pressure plate, and the underground ground 32b
A pressure resistant plate 42 having a small thickness T ₁ is formed on the upper surface.

Here, FIG. 4 shows a detailed structure of a circled portion indicated by reference numeral A in FIG. Reference numeral 38a,
Reference numeral 38b indicates a reinforcing bar for footing, and reference numerals 42a and 42b indicate reinforcing bars for a pressure plate. Among these reinforcing bars, the reinforcing bar for footing 38a and the reinforcing bar for a pressure plate 42a are connected in advance by a joint means such as a screw joint or a sleeve joint. Has been done.

FIG. 5 shows the detailed structure of the circled portion B in FIG. 3, in which the penetrating portion of the existing pile 6 into the pressure plate 42 is elastically deformable, for example, made of rigid rubber or the like. A ring-shaped insulating material 44 is externally fitted. In addition, the elliptical mark portion indicated by reference numeral C in FIG. 3 has the same structure as that in FIG. 5, that is, the insulating material 44 is externally fitted to the penetrating portion of the existing pile 6 into the footing 38.

Next, as shown in FIG. 6, footing 3
8 and the upper surface of the pressure plate 42, the expanded diameter portion 46 integrated with the existing pile 6 is formed. That is, FIG. 7 shows the expanded diameter portion 46 formed on the pressure resistant plate 42. When chemical anchoring is performed on the outer peripheral surface of the existing pile 6, that is, a plurality of holes are formed in the existing pile 6,
A plurality of anchor streaks 46a are inserted and fixed in these holes together with a resin and a curing accelerator. And existing pile 6
Reinforcing bars 46b, 4 connected to anchor bar 46a
Arrange 6c. Then, by placing concrete on these reinforcing bars 46b and 46c, the outer diameter is expanded from the existing pile 6, and the expanded diameter portion 46 that is in contact with the upper surface of the pressure plate 42 is formed.

Next, although not shown, a hydraulic jack is installed between the pressure plate 42 and the lower part of the frame 2a to support the vertical load of the existing building 2. Then, the tip end portion of the existing pile 6 extending from each expanded diameter portion 46 to the lower body portion 2a is disassembled, and as shown in FIG. 8, seismic isolation is performed between the expanded diameter portion 46 and the lower body portion 2a. The device 48 is installed. The seismic isolation device 48 employs, for example, an isolator in which a plurality of steel plates and rubber sheets are alternately laminated to form a columnar shape.

Then, the support of the existing building 2 by the above-mentioned hydraulic jack is released, and the vertical load of the existing building 2 is introduced into the existing pile 6 via the seismic isolation device 48. As a result, a pit 50 surrounding the lower part of the body 2a of the existing building 2 and having the seismic isolation device 48 installed is constructed. Even if seismic force is transmitted to the existing piles 6 when an earthquake occurs, the existing building 2 is retained within the retaining wall 40. The seismic isolation device 48 absorbs the seismic force while performing the displacement operation in the horizontal direction, and reduces the shaking of the existing building 2 as much as possible.

Therefore, this embodiment can obtain the following operational effects. That is, in the pit 50 of the present embodiment, the insulating material 44 is externally fitted to the penetrating portion of the existing pile 6 penetrating the pressure plate 42 to cut the edges of the pressure plate 42 and the existing pile 6. Since the weight of No. 2 is directly supported by the underground soil 32b, the supporting force received by the second new pile 36 can be reduced, and the weight burden on the existing pile 6 does not increase.

The first new pile 34 buried on the side of the retaining wall 8 supports the weight of the retaining wall 40 and the footing 38, and the second new pile 36 applies the earth pressure and the footing 38 to the retaining wall 40. Support the weight of. Further, even if water pressure is applied from the lower surface side of the pressure plate 42 (arrow indicated by symbol P ₁ in FIG. 8), the enlarged diameter portion 46 integrally formed on the upper portion of the existing pile 6 contacts the upper surface of the pressure plate 42, and Since the plate 42 is prevented from rising, the lightweight pressure-resistant plate 42, that is, the thickness T ₁ of the pressure-resistant plate 42 can be set small. This allows
The underground ground 32b becomes a shallow underground space 32, and the mountain retaining wall 8
Does not have to be buried to a deeper position, and the amount of excavated soil can be reduced. Further, the pressure plate 42 can be formed with a small amount of concrete. Therefore,
This embodiment can shorten the construction period and the construction cost.

Next, FIG. 9 shows a second embodiment of the present invention. The same components as those of the first embodiment shown in FIGS. 1 to 8 are designated by the same reference numerals. And its description is omitted. In the present embodiment, after the underground space 32 is formed, a plurality of new pressure-resistant plate piles 52 are buried at predetermined intervals over the entire area of the underground ground where the pressure-resistant plates are formed. Then, a pressure plate 54 integrated with the upper ends of the new pressure plate piles 52 is formed.

Here, as in the first embodiment, the circled portion indicated by reference symbol B in the drawing is an elastically deformable ring-shaped member made of, for example, rigid rubber, in the penetrating portion of the existing pile 6 into the pressure plate 54. Insulation material 44 is externally fitted. Further, in the present embodiment, the expanded diameter portion 46 is not formed on the upper portion of the existing pile 6. According to the above structure, the insulating material 44 is fitted on the penetrating portion of the existing pile 6 penetrating the pressure plate 54 to cut the edges of the pressure plate 54 and the existing pile 6, and the weight of the pressure plate 54 is newly provided for the pressure plate. Since the piles 52 support, the supporting force received by the existing piles 6 can be reduced.

Further, even if the water pressure P ₂ is applied from the lower surface side of the pressure plate 54, the new pressure plate piles 52 integrated and embedded in the pressure plate 54 prevent the pressure plate 54 from rising. The pressure plate can be made lighter, and the pressure plate 5
The thickness T _{2 of} 4 can be set small. As a result, as in the first embodiment, the underground space 3 having a shallow underground ground
2, it is not necessary to bury the mountain retaining wall 8 to a deep position, and the amount of excavated soil can be reduced. Further, since the pressure plate 54 can be formed with a small amount of concrete, it is possible to shorten the construction period and the construction cost.

In the first and second embodiments, the seismic isolation device 48 is installed between the upper part of the existing pile 6 and the lower part 2a of the skeleton, but the invention is not limited to this. The seismic isolation device 48 may be installed between the lower body 2a and the lower body 2a. Further, in each of the embodiments, the mountain retaining wall 8 is embedded in the soil around the existing building 2 in order to form the dry area 10, but the gist of the present invention is not limited to this, and for example, the mountain retaining wall 8 is used. Alternatively, a TUD pile (wall-shaped pile) may be embedded, and this TUD pile may be used as a part of the retaining wall structure.

In the above embodiment, the lower part 2a of the skeleton of the existing building 2 has been described as a flat shape. However, in the case where a lower part of the skeleton having an uneven bottom surface is formed, the lower part of the skeleton is formed. The ground beneath the bottom of the uneven surface is cut off to form an underground space.

[0025]

As described above, according to the method for constructing a seismic isolation pit for an existing building according to claim 1, the existing pile penetrates the pressure-resistant plate with its edge cut, and the weight of the pressure-resistant plate is the underground ground. Since it directly supports the new pile, it is possible to reduce the support force received by the new pile, and the weight load of the existing pile is not increased.

Further, even if water pressure is applied from the lower surface side of the pressure plate, the expanded portion integrally formed on the upper part of the existing pile prevents the pressure plate from rising, so that the pressure plate is lightweight, that is, the thickness of the pressure plate. Can be set thin. This allows
The amount of excavated soil is small because it is only necessary to form a small underground space with a shallow depth of underground ground. Further, since it is only necessary to form a pressure plate having a small thickness, the amount of concrete used is reduced. Therefore, the present invention can shorten the construction period and the construction cost.

According to the method for constructing a seismic isolation pit for an existing building according to claim 2, the existing pile is cut off from the pressure plate, and the weight of the pressure plate is supported by a plurality of new piles for pressure plates. Therefore, it does not increase the weight burden of the existing piles. And even if water pressure is applied from the lower surface side of the pressure plate, the new pressure plate sill buried in the ground prevents the pressure plate from rising, so the thickness of the light pressure plate, that is, the thickness of the pressure plate is set thin. be able to. As a result, similar to the effect of the first aspect, it is possible to provide a seismic isolation pit construction method for an existing building, which can shorten the construction period and the construction cost.

[Brief description of the drawings]

FIG. 1 is a view showing a state in which a dry area and an underground space are formed around an existing building in the present invention.

FIG. 2 is a diagram showing a state in which a new pile is buried in the underground ground in the dry area in the first embodiment of the present invention.

FIG. 3 is a view showing a state in which a footing, a retaining wall and a pressure plate are formed in the first embodiment.

FIG. 4 is a diagram showing a structure of a connecting portion of a footing and a pressure plate.

FIG. 5 is a view showing the structure of an existing pile that penetrates the pressure plate with its edge cut.

FIG. 6 is a view showing a state in which a diameter-expanded portion is integrally formed on an upper portion of an existing pile.

FIG. 7 is a diagram specifically showing the structure of the expanded diameter portion.

FIG. 8 is a diagram showing a state where a seismic isolation device is installed in the pit of the first embodiment.

FIG. 9 is a view showing a state in which a seismic isolation device is installed in a pit according to the second embodiment.

FIG. 10 is a diagram showing a state where a dry area and an underground space are formed around an existing building in a conventional seismic isolation pit construction method.

FIG. 11 is a diagram showing a structure of a conventional seismic isolation pit.

[Explanation of symbols]

 2 Existing building 2a Lower part of frame 2b Side wall of structure 6 Existing pile 10 Dry area 32 Underground space 32a, 32b Underground ground 34 New pile (New pile for footing) 36 New pile 38 Footing 40 Retaining wall 42, 54 Pressure plate 46 Expanding part 48 Seismic Isolation Device 50 Pits 52 New Pile for Pressure Plate

Claims (2)

[Claims] 1. A method of constructing a seismic isolation pit so as to surround a lower part of a body and a side wall of a body of the existing building when a seismic isolation device is newly installed in the existing building, which comprises excavating a ground around the existing building. And forming a dry area, and along the lower part of the frame of the existing building, roots the ground directly below the lower part of the structure to form an underground space communicating with the lower part of the dry area, and existing in this underground space Exposing the upper part of the pile, embedding a new pile in the ground below the dry area, forming footing integrally with the new pile in the ground below the dry area, in the dry area The step of integrally forming a retaining wall surrounding the side wall of the body with the upper part of the footing, and forming a pressure plate in the underground space by cutting the edge with the existing pile and increasing the contact area with the underground ground. You Along with the step of connecting the pressure plate and the footing, a diameter-expanded portion is integrally formed on the outer periphery of the upper part of the existing pile, and the pressure-expansion portion is brought into contact with the upper surface of the pressure plate to cause the pressure resistance by water pressure. A method for constructing a seismic isolation pit for an existing building, which comprises a step of preventing the plate from rising. 2. A method of constructing a seismic isolation pit so as to surround a lower part of a body and a side wall of a body of the existing building when a seismic isolation device is newly installed in the existing building. And forming a dry area, and along the lower part of the frame of the existing building, roots the ground directly below the lower part of the structure to form an underground space communicating with the lower part of the dry area, and existing in this underground space The step of exposing the upper part of the pile, and burying new footing piles in the ground below the dry area, and burying a plurality of new pressure piles at a predetermined interval in the underground ground of the underground space. And the step of forming a footing integrally with the new footing pile on the lower ground of the dry area, in the dry area,
A step of integrally forming a retaining wall surrounding a side wall of the body with the upper portion of the footing, cutting an edge with the existing pile in the underground space, and integrally forming a pressure plate with a new pressure plate for a pressure plate embedded in the underground ground And a step of connecting the pressure resistant plate and the footing together with each other, and a method for constructing a seismic isolation pit for an existing building.