JP6855365B2 - Underground structure of new building - Google Patents

Description

The present invention relates to an underground structure of a new building provided on the inner side surrounded by the existing underground skeleton or on the upper side of the existing underground skeleton.

When rebuilding an existing building into a new building, the new building is being constructed by partially leaving the foundation frame of the existing building.
For example, in Patent Document 1, the existing structure supported by the existing pile is removed leaving the existing pile and the existing foundation slab arranged on the existing pile, and backfilled on the remaining existing foundation slab. The new structure constructed by laying the material and arranging the new mat slab of the foundation of the new structure on the backfill material is disclosed.
In the configuration as disclosed in Patent Document 1, the underground outer wall of the existing structure has been removed. However, the underground outer wall of the existing structure may be left in order to be used, for example, as a retaining material or as a part of the structure of a new building.

Patent Document 2 describes a building construction method in which an existing building is removed while leaving at least an existing pile among the existing buildings, and a new building is constructed on the site of the removed existing building, and the weight of the new building is transmitted to the existing pile. Therefore, a building construction method is disclosed in which a skeleton structure composed of a large number of long members is used, the skeleton structure is installed on an existing pile, and a new building is constructed on the skeleton structure. ing.
Further, it is disclosed that the existing building will be removed while leaving the existing foundation beam, the existing bottom plate, and the existing outer wall in addition to the existing pile if it can be reused.
In Patent Document 3, the existing underground structure is partially dismantled to leave the underground outer wall and the underground basement, and the underground outer wall and the underground bottom are filled with a filler to construct the foundation ground, and a new building is constructed on the foundation ground. The configuration for constructing the underground structure of is disclosed.

In the configuration disclosed in Patent Documents 2 and 3, the vertical load borne by the newly constructed underground structure may be transmitted to the existing underground outer wall. The existing underground outer wall is not always provided on the assumption that it will bear the vertical load. For this reason, it is necessary to design a new building while considering the vertical load that can be borne by the underground outer wall, which complicates the design work.

Japanese Unexamined Patent Publication No. 2010-121372 Japanese Unexamined Patent Publication No. 2006-161476 JP-A-2015-34436

An object of the present invention is to provide an underground structure of a new building using an existing underground skeleton, which does not require complicated design work.

As an underground structure of a new building using an existing underground skeleton, the present inventors use the existing underground outer wall as a retaining wall, separate the upper end surface of the existing underground outer wall from the new underground skeleton, and the existing underground. By connecting the skeleton (existing underground outer wall or existing pressure plate) and the new underground skeleton with a bonded steel material, it is not necessary to design the existing underground outer wall as a structural member, and in the event of an earthquake, the existing underground skeleton is connected to the new underground skeleton. The present invention was made by focusing on the fact that the weight of the underground skeleton can be used as a counter weight.
The present invention employs the following means in order to solve the above problems.
That is, the underground structure of the new building of the present invention is an underground structure of a new building in which a new underground skeleton is provided on the inner side surrounded by the existing underground skeleton or on the upper side of the existing underground skeleton. The underground skeleton is configured to include an existing underground outer wall and an existing pressure plate, and there is a gap or buffer between the upper end surface of the existing underground outer wall and the new underground skeleton located above the upper end surface. It is characterized in that a material is provided.
According to such a configuration, a gap with zero rigidity or a low-rigidity cushioning material is provided between the upper end surface of the existing underground outer wall and the new underground skeleton, and the existing underground outer wall and the new underground skeleton are mechanically separated. Therefore, the vertical load of the superstructure constituting the new building is not transmitted to the existing underground outer wall, and the new building is supported only by the new underground skeleton. Therefore, when designing a new building, the existing underground outer wall can be designed without considering the burden of the vertical load of the new building, and complicated design work is not required.
In addition, since the existing underground outer wall can be used as a retaining wall at the time of construction, it is not necessary to newly install a retaining wall when constructing a new underground skeleton, the construction cost can be reduced, and the number of working days can be shortened. ..

In one aspect of the present invention, in the underground structure of the new building of the present invention, a gap or a cushioning material is provided between the inner side surface of the existing underground outer wall and the new underground skeleton.
According to such a configuration, a gap or a cushioning material is provided between the inner side surface of the existing underground outer wall and the new underground skeleton, so that the new underground skeleton can be connected to the existing underground outer wall. No vertical load or the like is transmitted, and the existing underground outer wall can be designed relatively easily as a non-structural member.

In one aspect of the present invention, in the underground structure of the new building of the present invention, a bonded steel material is installed between the existing underground outer wall and the new underground skeleton, and between the existing pressure plate and the new underground skeleton. Then, the existing underground skeleton and the new underground skeleton are joined via the joined steel material.
According to such a configuration, the existing underground skeleton and the new underground skeleton are joined via the bonded steel material, so that the weight of the existing underground skeleton including the existing underground outer wall and the existing pressure plate can be used as the counterweight of the new underground skeleton. Available. In addition, since the new underground skeleton is joined to the existing underground outer wall or the existing pressure plate via the joined steel material, the joined steel material functions as a pull-out resistance material against the overturning moment generated at the building leg when an earthquake occurs. At the same time, a bearing resistance force acts on the horizontal joint surface between the new underground skeleton and the existing pressure plate to form a resistance moment, which can suppress the rotation of the building. As a result, the seismic resistance of new buildings can be improved.

According to the present invention, it is possible to provide an underground structure of a new building using an existing underground skeleton, which does not require complicated design work.

It is sectional drawing which shows the whole structure of the new building which concerns on 1st Embodiment of this invention. It is a partially enlarged sectional view which shows a part of the underground structure part of the new building of FIG. It is explanatory drawing of the resistance mechanism of the new building which concerns on the said 1st Embodiment. It is sectional drawing which shows the whole structure of the new building which concerns on 2nd Embodiment of this invention. It is a partially enlarged sectional view which shows a part of the underground structure part of the new building of FIG. It is sectional drawing which shows the structure of the modification of the new building which concerns on 2nd Embodiment of this invention.

In the present invention, a gap or a cushioning material is provided between the existing underground outer wall and the new underground skeleton to mechanically separate the existing underground skeleton (existing underground outer wall, existing pressure plate) and the new underground skeleton with a bonded steel material. It is the underground structure of the new building that was connected. The first embodiment is an underground structure of a new building in a direct foundation type in which a new underground skeleton is provided on the upper surface of an existing pressure plate (FIGS. 1 to 2). The second embodiment and its modification are underground structures of a new building in the form of a pile foundation provided with existing piles and new piles (FIGS. 4 to 6).
Hereinafter, with reference to the attached drawings, a mode for carrying out the underground structure of the new building according to the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 shows a cross-sectional view showing the overall configuration of the new building according to the first embodiment of the present invention. FIG. 2 shows a partially enlarged cross-sectional view showing a part of the underground structure of the new building of FIG.
As shown in FIGS. 1 and 2, the new building 1A includes an underground structure portion (underground structure of the new building) 10A and a superstructure portion 20.
The superstructure portion 20 is provided on the underground structure portion 10A. The superstructure portion 20 includes a plurality of upper pillars 21 and upper beams 22 erected between the upper pillars 21 adjacent to each other.

As shown in FIGS. 1 and 2, the underground structure portion 10A has a gap S1, S2, or a buffer provided between the existing underground skeleton 30, the new underground skeleton 11A, and the existing underground skeleton and the new underground skeleton. It is composed of materials 41 and 42.
The existing underground skeleton 30 is at least a part of the foundation of the existing building, and is configured to be left in the ground G when the existing building (not shown) is demolished prior to the construction of the new building 1A.
The existing underground skeleton 30 includes an existing pressure plate 31 formed on the ground G and an existing underground outer wall 32 rising upward from the outer peripheral portion of the existing pressure plate 31. The outer peripheral surface 32f of the existing underground outer wall 32 is in contact with the surrounding ground G.
The existing pressure plate 31 and the existing underground outer wall 32 are formed of a reinforced concrete structure or the like.

The new underground skeleton 11A is provided on the inner side surrounded by the existing underground skeleton 30. The new underground skeleton 11A includes a new pressure plate 12, a new underground outer wall 13, a lower column 14, and a foundation beam 15.
The new pressure plate 12 is formed on the existing pressure plate 31 with a predetermined thickness. The new pressure plate 12 may be formed on the concrete 9 provided on the existing pressure plate 31 with a predetermined thickness.
The new underground outer wall 13 is formed so as to rise upward from the outer peripheral portion of the new pressure plate 12. As a result, the new underground skeleton 11A is provided on the upper side of the existing underground skeleton 30.
The new pressure plate 12 and the new underground outer wall 13 are formed of a reinforced concrete structure, a steel-framed reinforced concrete structure, or the like.
The lower pillar 14 extends vertically upward from the newly installed pressure plate 12. The foundation beam 15 is erected between the lower pillar 14 adjacent to each other and the new underground outer wall 13.

As shown in FIG. 2, the new underground outer wall 13 is formed so as to project upward from the upper end surface 32t of the existing underground outer wall 32. The new underground outer wall 13 has an overhanging portion 13w that projects toward the outer peripheral side above the upper end surface 32t of the existing underground outer wall 32. The overhanging portion 13w can be formed by, for example, an outer peripheral foundation beam 15w located on the outer peripheral portion of the new underground skeleton 11A.
A gap S1 is formed in the vertical direction between the upper end surface 32t of the existing underground outer wall 32 and the lower surface 13b of the overhanging portion 13w of the new underground outer wall 13 located above the upper end surface 32t.
Further, a gap S2 having a predetermined size is formed in the horizontal direction between the outer peripheral surface 13f of the new underground outer wall 13 and the inner side surface 32g of the existing underground outer wall 32.
The gaps S1 and S2 may be filled with cushioning materials 41 and 42 made of, for example, a foaming foam material such as polypropylene. Further, low-strength concrete (for example, lapple concrete), which is not expected as earth and sand or a structural material, may be arranged in the gaps S1 and S2. With the above configuration, the vertical load borne by the new underground outer wall 13 is not transmitted to the existing underground outer wall 32.

As shown in FIG. 2, a joint steel material 51 made of an adhesive post-construction anchor bar or the like is provided between the existing underground outer wall 32 and the new underground skeleton 11A. The bonded steel material 51 extends in the horizontal direction, one end thereof is driven into the existing underground outer wall 32, and the other end is buried in the new underground outer wall 13 of the new underground skeleton 11A. A plurality of joined steel materials 51 are provided at appropriate intervals in the vertical direction and the horizontal direction. Here, the bonded steel material 51 is provided with a number and materials such that the vertical load borne by the new underground outer wall 13 is not transmitted to the existing underground outer wall 32.
A bonded steel material 52 made of an adhesive post-construction anchor bar or the like is provided between the existing pressure plate 31 and the new underground skeleton 11A. The bonded steel material 52 extends in the vertical direction, the lower end thereof is driven into the existing pressure plate 31, and the upper end is embedded in the new pressure plate 12 of the new underground skeleton 11A. A plurality of joined steel materials 52 are provided at appropriate intervals in two directions orthogonal to each other in the horizontal plane (for example, a direction along the paper surface of FIG. 2 and a direction orthogonal to the paper surface of FIG. 2).

In order to construct such a new building 1A, first, the existing building (not shown) is dismantled and removed leaving the existing underground skeleton 30 in the ground G.
After that, a new underground skeleton 11A is provided on the inner side surrounded by the existing underground skeleton 30. At this time, the existing underground outer wall 32 of the existing underground skeleton 30 functions as a retaining wall, and the surrounding ground can be solidified so that the surrounding ground G does not flow into the inner side surrounded by the existing underground outer wall.
After the construction of the new underground skeleton 11A, the construction of the new building 1A is completed by constructing the superstructure portion 20 on the new underground skeleton 11A.

Next, the resistance mechanism of the underground structure of the new building of the first embodiment will be described.
In the first embodiment, the existing pressure plate 31 and the existing underground outer wall 32 constituting the existing underground skeleton 30 are left behind, and the new pressure plate 12 is provided on the upper surface of the existing pressure plate 31, and the existing underground outer wall 32 is provided. It is an underground structure 10A of a new building 1A in which a new underground outer wall 13 is constructed along the inner side surface 32g. Further, gaps S1 and S2 and cushioning materials 41 and 42 are provided between the existing underground outer wall 32 and the new underground outer wall 13 to mechanically separate the existing underground outer wall 32, the new underground outer wall 13, and the existing pressure plate. 31 and the newly installed pressure plate 12 are connected by the bonded steel materials 51 and 52.
FIG. 3 shows a schematic view of the resistance mechanism of the underground structure of the new building of the first embodiment.
In the underground structure of the new building of the first embodiment, as shown in FIG. 3, the existing pressure plate 31 and the new pressure plate 12 are joined to the overturning moment OM generated at the building leg when an earthquake occurs. The steel material 52 bears the pull-out resistance force, and the bearing resistance force acts on both horizontal joint surfaces, and the couple force mechanism forms a resistance moment RM to prevent the building 1A from tipping over.
Specifically, the bonded steel material 52 provided between the existing pressure plate 31 and the new pressure plate 12 is concentrated on both end portions in the short side direction W when the building 1A is viewed in a plan view, as shown in FIG. 52 is provided along the long side direction L of the building orthogonal to the end side direction W in the horizontal plane. The both end portions of the building 1A in the short side direction W are referred to as the building 1A in order to efficiently bear the pull-out resistance force on the bonded steel material 52 against the overturning moment OM acting on the building leg. When the vicinity of the center of the short side direction W is regarded as the rotation center line of the building, the section corresponding to 1/3 or less of the short side length of the building 1A from the building end face in the short side direction W of the building 1A to the inside of the building. Become.

In the underground structure of the new building 1A as described above, as shown in FIG. 2, the new underground skeleton 11A is provided on the inner side surrounded by the existing underground skeleton 30 and on the upper side of the existing underground skeleton 30. The existing underground skeleton 30 includes an existing underground outer wall 32 and an existing pressure plate 31, and is located between the upper end surface 32t of the existing underground outer wall 32 and the new underground skeleton 11A located above the upper end surface 32t. , The gap S1 or the cushioning material 41 is provided.
According to such a configuration, a gap S1 having zero rigidity or a low-rigidity cushioning material 41 is provided between the upper end surface 32t of the existing underground outer wall 32 and the new underground skeleton 11A, and the existing underground outer wall 32 and the new underground are provided. Since the skeleton 11A is mechanically separated, the vertical load of the superstructure 20 constituting the new building 1A is not transmitted to the existing underground outer wall 32, and the new building 1A is supported only by the new underground skeleton 11A. Will be done. Therefore, when designing the new building 1A, the existing underground outer wall 32 can be designed without considering the load of the vertical load of the new building 1A, and complicated design work is not required.
Further, at the time of construction, since the existing underground outer wall 32 can be used as a retaining wall, it is not necessary to provide a retaining wall when constructing a new underground skeleton, the construction cost can be reduced, and the number of working days can be shortened.
Therefore, it is possible to provide the underground structure portion 10A of the new building 1A using the existing underground skeleton 30, which does not require complicated design work.

In the underground structure portion 10A of the new building 1A, a gap S2 or a cushioning material 42 is provided between the inner side surface 32g of the existing underground outer wall 32 and the new underground skeleton 11A.
According to such a configuration, the gap S2 or the cushioning material 42 is provided between the inner side surface 32 g of the existing underground outer wall 32 and the new underground skeleton 11A, so that the existing underground outer wall 32 and the new underground skeleton are provided. The vertical load of the new building 1A is not transmitted to and from 11A, and the existing underground outer wall 32 can be relatively easily designed as a non-structural member.

In the underground structure portion 10A of the new building 1A, joining steel materials 51 and 52 are installed between the existing underground outer wall 32 and the new underground skeleton 11A, and between the existing pressure plate 31 and the new underground skeleton 11A. , 52, the existing underground skeleton 30 and the new underground skeleton 11A are joined.
According to such a configuration, since the existing underground skeleton 30 and the new underground skeleton 11A are joined via the bonded steel materials 51 and 52, the weight of the existing underground skeleton 30 including the existing underground outer wall 32 and the existing pressure plate 31 can be reduced. , Can be used as a counterweight for the new underground skeleton 11A. Further, since the new underground skeleton 11A and the existing underground outer wall 32 or the existing pressure plate 31 are joined via the joined steel materials 51 and 52, the joined steel material is opposed to the overturning moment OM generated in the building leg when an earthquake occurs. 51 and 52 function as pull-out resistance materials, and a bearing resistance force acts on the horizontal joint surface between the new underground skeleton 11A and the existing pressure plate 31 to form a resistance moment RM, which suppresses the rotation of the building 1A. be able to. As a result, the seismic resistance of the new building 1A can be improved.

[Second Embodiment]
Next, a second embodiment of the underground structure of the new building of the present invention will be described. The second embodiment shown below differs from the underground structure of the new building shown in the first embodiment only in that it is provided with foundation piles. Therefore, in the following description, the differences from the first embodiment will be mainly described, and the same reference numerals will be given to the configurations common to the first embodiment, and the description thereof will be omitted.
FIG. 4 shows a cross-sectional view showing the overall configuration of the new building according to the second embodiment of the present invention. FIG. 5 shows a partially enlarged cross-sectional view showing a part of the underground structure portion of the new building of FIG. In FIG. 5, the leveling concrete 9 between the existing pressure plate 31 and the new pressure plate 12 is not shown.
As shown in FIGS. 4 and 5, the new building 1B includes an underground structure portion (underground structure) 10B and an upper structure portion 20. Further, the underground structure portion 10B is composed of an existing underground skeleton 30 and a new underground skeleton 11B.
The existing underground skeleton 30 includes an existing pressure plate 31, an existing underground outer wall 32, and an existing foundation pile 35. The existing foundation pile 35 is at least a part of the foundation portion of the existing building, and is configured to be left in the ground G together with the existing pressure plate 31 and the existing underground outer wall 32 when the existing building (not shown) is demolished. ..
In the existing foundation pile 35, the pile head 35t and, more specifically, the outer peripheral surface of the pile body at the upper part of the pile are joined to the existing pressure plate 31. The existing foundation pile 35 and the existing pressure plate 31 can also be joined via a joint bar (not shown).

As shown in FIG. 4, the new underground skeleton 11B is provided on the inner side surrounded by the existing underground skeleton 30. The new underground skeleton 11B includes a new pressure plate 12, a new underground outer wall 13, a lower column 14, and a foundation beam 15. Joint steel materials 51 and 52 (see FIG. 2) are installed between the existing underground outer wall 32 and the new underground skeleton 11B, and between the existing pressure plate 31 and the new underground skeleton 11B, as in the first embodiment. ing.
As shown in FIG. 5, the new pressure plate 12 is formed so that the recess 12s is recessed upward on the lower end surface, and has predetermined dimensions in the horizontal direction and the vertical direction between the recess 12s and the pile head 35t of the existing foundation pile 35. The gap S3 is provided. The gap S3 may be filled with a cushioning material 43 made of, for example, a foaming foam material such as polypropylene.

Similar to the new building 1A of the first embodiment, the new underground skeleton 11B is provided between the new underground skeleton 11B and the upper end surface of the existing underground outer wall 32 via a gap S1 or a cushioning material 41. Further, a gap S2 or a cushioning material 42 is provided between the inner side surface of the existing underground outer wall 32 and the new underground skeleton 11B. As a result, when designing the new building 1B, the design work can be performed without considering the load of the vertical load due to the existing underground outer wall 32, and the complexity of the design work can be suppressed.
Further, as shown in FIG. 5, the existing foundation pile 35 is also provided between the new underground skeleton 11B and the new pressure plate 12 via a gap S3 or a cushioning material 43. As a result, when designing the new building 1B, the design work can be performed without considering the load of the vertical load due to the existing foundation pile 35, and the complexity of the design work can be suppressed.
According to the configuration of the second embodiment as described above, a gap S3 or a cushioning material 43 is provided between the new pressure plate 12 constituting the new underground skeleton 11B and the existing foundation pile 35, and the new pressure plate 12 is provided. And the existing foundation pile 35 are mechanically separated, so that the vertical load of the new building 1B is not transmitted to the existing foundation pile 35, and the new pressure plate 12 passes through the existing pressure plate 31 on the lower surface side thereof. It is transmitted to the direct base plate of the existing pressure plate 31. Although the existing foundation pile 35 does not support the vertical load of the new building 1B, the new underground skeleton 11B including the new pressure plate 12 moves in the horizontal direction when an earthquake occurs, and the existing foundation pile 35 and the new pressure plate 12 are separated from each other. When the gap space is narrowed and the new pressure plate 12 reaches a deformed area in contact with the existing foundation pile, the existing foundation pile 35 functions as a horizontal resistance material for the new building 1B and enhances the structural safety of the new building 1B. be able to.

(Modified example of the second embodiment)
The underground structure of the new building of the present invention is not limited to the above-mentioned second embodiment described with reference to the drawings, and various modifications can be considered within the technical scope thereof.
For example, in the above embodiment, the existing foundation pile 35 is provided in the new underground skeleton 11B, but the present invention is not limited to this.
FIG. 6 shows a cross-sectional view showing the configuration of a modified example of the new building according to the second embodiment of the present invention. The underground structure portion (underground structure) 10C of the new building 1C is composed of an existing underground skeleton 30 and a new underground skeleton 11C.
The new underground skeleton 11C includes a new foundation pile 18. The pile head 18t of the new foundation pile 18 is integrally joined to the new underground skeleton 11C. The new foundation pile 18 and the new underground skeleton 11C can also be joined via a joint bar (not shown). The new foundation pile 18 is formed with a gap S4 having a predetermined size separated from the through hole 31h formed in the existing pressure plate 31. The gap S4 may be filled with a cushioning material 44 made of, for example, a foaming foam material such as polypropylene.
According to the configuration of the modified example of the second embodiment as described above, a gap S4 or a cushioning material 44 is provided between the existing pressure plate 31 and the new foundation pile 18, and the existing pressure plate 31 and the new foundation pile 18 are provided. Since the 18 is mechanically separated, the force is not transmitted from the existing pressure plate 31 to the new foundation pile 18 during normal times other than when an earthquake occurs, and the existing pressure plate 31 is transferred to the new foundation pile 18 when an earthquake occurs. When the deformation region is reached, the existing pressure plate 31 and the new pressure plate 12 are both in contact with the new foundation pile 18, and the existing pressure plate 31 functions as a horizontal resistance material for the new building 1C to form a new building. The structural safety of 1C can be enhanced.

(Other variants)
Further, the underground structure portion of the new building may include both the existing foundation pile 35 shown in the second embodiment and the new foundation pile 18 shown in the modified example of the second embodiment. In that case, the existing foundation pile 35 has the structure shown in FIG. 5, and the structure of the new foundation pile 18 and its surroundings adopts the structure shown in FIG.
Further, a recess between the existing foundation pile 35 and the new pressure plate 12 in the second embodiment, and a through hole portion of the existing pressure plate 31 through which the new foundation pile 18 is inserted in the modified example of the second embodiment. Was provided with a gap or a cushioning material, but instead of this, low-strength concrete, which is not expected as a structural material, may be arranged.
In addition to this, as long as the gist of the present invention is not deviated, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.

1A, 1B, 1C New building 31h Through hole 9 Leveling concrete 31 Existing pressure plate 10A, 10B, 10C Underground structure 32 Existing underground outer wall
(Underground structure of new building) 32g Internal side side surface 11A, 11B, 11C New underground skeleton 32t Upper end surface 12 New pressure board 35 Existing foundation pile 18 New foundation pile 41, 42 Cushioning material 20 Upper structure part 51, 52 Joint steel material 30 Existing Underground skeleton S1, S2, S3, S4 Gap

Claims (3)

It is the underground structure of a new building with a new underground skeleton on the inner side and upper side surrounded by the existing underground skeleton.
The existing underground skeleton is configured to include an existing underground outer wall and an existing pressure plate.
The new underground skeleton includes a new pressure plate provided on the upper surface of the existing pressure plate and a new underground outer wall constructed along the inner side surface of the existing underground outer wall.
A gap or cushioning is provided between the upper end surface of the existing underground outer wall and the new underground outer wall located above the upper end surface, and between the inner side surface of the existing underground outer wall and the new underground outer wall. The underground structure of a new building, which is characterized by being provided with materials. A bonded steel material is installed between the existing underground outer wall and the new underground outer wall, and between the existing pressure plate and the new pressure plate, and the existing underground skeleton and the new underground skeleton are connected through the bonded steel material. The underground structure of the new building according to claim 1 or 2, wherein the new building is joined. The existing underground skeleton is further equipped with existing foundation piles.
The upper part of the pile of the existing foundation pile is joined to the existing pressure plate, and the pile head of the existing foundation pile protrudes upward from the existing pressure plate.
On the lower end surface of the newly installed pressure plate, a recess is formed so as to be recessed upward so as to cover the pile head of the existing foundation pile.
The underground structure of a new building according to claim 1 or 2, wherein a gap or a cushioning material is provided between the recess of the new pressure plate and the pile head of the existing foundation pile.

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