JP7790936B2 - How to build underground structures - Google Patents

Description

The present invention relates to a method for constructing an underground structure by removing an existing structure and constructing an additional underground structure.

For example, Patent Document 1 describes a method for constructing an underground structure in which an existing underground structure is removed and a new one is constructed. According to this underground structure construction method, a new underground structure is constructed while the existing underground structure is demolished, based on an inverted construction method in which an underground structure is constructed while excavating the ground. This underground structure construction method comprises the following steps:

A retaining wall is constructed around the perimeter of the existing underground structure. Next, structural columns are installed to serve as temporary supports, penetrating the underground structure of the existing underground structure. Next, the upper basement floor of the existing structure is demolished, and excavation is carried out beneath the existing foundations. Next, temporary supports are attached to the structural columns and retaining walls, and the entire existing structure is supported by these temporary supports, and the first floor is constructed. Next, excavation continues beneath the existing structure, and once the floor is laid, the new foundations are constructed. From then on, the demolition of the existing underground structure, the construction of the new underground structure, and the construction of the new above-ground structure will be carried out in parallel as appropriate.

Japanese Patent Application Laid-Open No. 2001-262595

Inverted construction methods, such as the method for constructing underground structures described in Patent Document 1, can be difficult, for example, in deep construction work when there is nearby public transportation. For example, when using inverted construction methods to install a ramp around the perimeter of the construction area, pouring concrete using a press-in method, in which concrete is pumped in from the bottom of vertical members such as pillars, can be difficult. In inverted construction methods, such as the method for constructing underground structures described in Patent Document 1, for example, to ensure accuracy, the structural columns are assembled above ground (hereinafter also referred to as "ground assembly") and then constructed underground. However, when the construction site is small, constructing a pilot floor on the first floor and then constructing the structural columns underground can result in the structural columns being longer than the site, making it impossible to secure space for ground assembly.

In the inverted construction method for constructing underground structures described in Patent Document 1, when excavated soil and demolition debris are collected and removed from a temporary opening, they must be collected below the opening, which can make it difficult to move and operate heavy machinery.

The present invention aims to provide a method for constructing a structure that allows for the efficient removal of existing underground structures while adding new ones, even in a small area.

One aspect of the present invention is a method for constructing a retaining wall around the periphery of an existing underground structure; removing the existing underground structure for a first predetermined number of floors below the first floor of the existing underground structure; installing a first temporary earth retaining support supporting the retaining wall from a first ground surface revealed by removing the basement floors to the height of the first floor; constructing a plurality of structural columns from the first ground surface to a first predetermined depth below; constructing a new basement floor surface on the first ground surface; and sequentially constructing a first predetermined number of new underground structures above the new basement floor surface to form the new first floor. This method for constructing an underground structure comprises the steps of: constructing new ground floors from the new first floor floor surface upwards; excavating the ground below the new basement floor surface to a second ground surface at a second predetermined depth shallower than the first predetermined depth; constructing a foundation on the second ground surface; installing second temporary earth retaining supports that support the retaining wall from the foundation to the height of the new basement floor surface; and sequentially constructing additional new underground structures for a second predetermined number of floors upwards from the foundation.

According to the present invention, when constructing a structural column, the column capital can be extended to the first ground surface, allowing the structural column to be shortened. By shortening the structural column, there is an advantage in that the structural column can be assembled on the ground even if the construction area 1 is narrow. According to the present invention, even the existing underground structure is removed, a new underground floor surface is constructed on the first ground surface, and the new underground structure is constructed above that using the pour-in-place method, allowing the new underground structure to be constructed stably.

Furthermore, the first ground surface of the present invention may have a depth level that is shallower than the groundwater level.

According to the present invention, new underground structures can be constructed at a shallower position than the groundwater level, allowing for stable construction of new underground structures.

The present invention may also include a step of constructing an underground slope connecting the new underground structure of the first predetermined number of floors to the new first floor floor.

According to the present invention, underground slopes can be constructed with consistent quality using the sequential pouring method.

The present invention may also include a step of constructing an additional underground slope upward from the foundation.

According to the present invention, an additional underground slope can be constructed with consistent quality using the pour-in-place method.

Furthermore, when the underground slope and the additional underground slope are provided in the construction of the new underground structure and the construction of the additional new underground structure, the present invention may also include a process of using the underground slope and the additional underground slope to transport removed materials and to transport carried-in materials.

According to the present invention, by constructing an underground ramp and an additional underground ramp, removed and delivered items can be easily transported by vehicle.

This invention makes it possible to efficiently remove existing underground structures while constructing new underground structures, even on small plots of land.

FIG. 2 is a plan view showing the construction target area of an underground structure according to an embodiment of the present invention. 1 is a diagram showing the steps of constructing a diaphragm wall in a method of constructing an underground structure. FIG. This is a diagram showing the process of removing part of an existing underground structure and constructing a structural column in a method of constructing an underground structure. This is a diagram showing the process of installing the first temporary retaining support in the method of constructing an underground structure. FIG. 1 is a diagram showing the steps of constructing a new underground structure in a method for constructing an underground structure. This is a diagram showing the construction of a new underground structure using the underground structure construction method. 1 is a diagram showing the steps of constructing an underground slope in a method for constructing an underground structure. FIG. 10 is a diagram showing the step of excavating the ground below a new underground structure in the method for constructing an underground structure. This shows the underground structure construction method after an additional new underground structure has been constructed below the new underground structure. FIG. 10 is a diagram showing the steps of constructing an additional new underground slope in the underground structure construction method.

Below, each step of the method for constructing an underground structure according to the present invention will be explained with reference to the drawings.

As shown in Figures 1 and 2, the construction area 1 in which a new building will be constructed is, for example, a narrow lot. For example, the construction area 1 is close to major roads, public transportation, other buildings, etc. For example, the construction area 1 is a location where the above-ground floor of an existing building has been removed, leaving a first predetermined number of existing underground structures 2 below the first floor. In this embodiment, the first predetermined number of floors is the number of floors of the existing underground structure 2, for example, two underground floors. A groundwater level W exists at a lower level than the floor of the existing underground structure 2. Deep construction work is being carried out in the construction area 1, and a new underground structure (described below) is being constructed even deeper underground than the existing underground structure 2.

First, a retaining wall 3 is constructed around the perimeter of the existing underground structure 2 to prevent the collapse of the ground. The retaining wall 3 is constructed, for example, based on the diaphragm wall construction method. The diaphragm wall construction method involves, for example, excavating a wall-shaped trench while injecting stabilizing fluid into the trench to prevent the excavated wall surface from collapsing, digging underground, pouring concrete into the trench, and constructing a continuous diaphragm wall (the retaining wall 3) made of plain or reinforced concrete underground. The diaphragm wall is constructed based on the SMW (Soil Mixing Wall) method. The diaphragm wall is constructed by mixing and stirring cement milk and soil in the trench to form a water-stopping wall, and then inserting H-shaped steel beams to form the continuous retaining wall 3.

The trench is formed, for example, by forming a series of cylindrical excavation holes. A stabilizing fluid is injected into the excavation holes to prevent the hole walls from collapsing and to prevent the slime from settling, thereby maintaining the wall surface of the excavation hole. The stabilizing fluid is, for example, a bentonite solution, and its quality is controlled based on specific gravity, viscosity, sand content, pH, etc. The retaining wall 3 may also be constructed using other construction methods, such as sheet piles. The existing underground structure 2 is removed sequentially, starting from the first floor. At this time, the internal space 2S of the existing underground structure 2 is filled with backfill soil 2B. The backfill soil 2B is, for example, liquefied treated soil. The backfill soil 2B is filled from the ground level. The backfill soil 2B is excavated depending on the state of the existing underground structure 2 after removal.

As shown in Figure 3, a gantry F is constructed to serve as a temporary floor in the opening that appears after the first floor of the existing underground structure 2 is removed. The gantry F is constructed to cover only part of the first floor, not the entire surface. The gantry F is constructed to be rectangular in shape when viewed from above. In parallel with the installation of the gantry F, a number of temporary gantry piles F2 are installed below the gantry F to support the gantry F. The gantry piles F2 are formed, for example, from H-beam steel. The gantry piles F2 are embedded, for example, to a position lower than the second ground surface 12 (see Figure 7) that supports the new underground structure 8 described below. The gantry piles F2 are constructed by appropriately extending the H-beam steel. This makes it possible to transport the removed object T from the gantry F below. Heavy machinery such as cranes and vehicles are placed on the gantry F. The concrete blocks and backfill soil 2B made from the crushed existing underground structure 2 that remain below the platform F are removed one after another from above. The existing underground structure 2 is removed one after another from above, exposing the first ground surface 5.

A plurality of structural columns 6 are constructed from the first ground surface 5 to a first predetermined depth below. The structural columns 6 are support columns for supporting the pilot floor, which is constructed first in the inverted construction method. The structural columns 6 are, for example, columns formed by encasing steel materials such as H-beams in concrete. The structural columns 6 are constructed integrally with foundation piles 6A and used as part of a structure. In constructing the structural columns 6, for example, pile holes are excavated downward from the existing underground structure 2 or the first ground surface 5, and stabilizing fluid is injected into the pile holes. The pile holes are then excavated downward while maintaining their stability, forming a vertical hole-like space. The vertical hole-like space has, for example, an expanded diameter space with a tapered diameter at the bottom. The expanded diameter space is formed, for example, using an expanding device (not shown) or the like.

A reinforcing bar cage (not shown) made of rebar is erected in the expansion space. A foundation pile 6A is formed in the vertical hole, into which concrete is poured. A structural column 6 is positioned and erected above the foundation pile before the concrete hardens. A structural column 6 assembled to the ground using H-beam steel is inserted into the vertical hole-shaped space and embedded in the concrete. After the concrete hardens, the structural column 6 and foundation pile are formed as a single unit.

According to the above process, by constructing the structural columns 6 from the first ground surface 5, the structural columns 6 can be constructed in a shorter length than when using the inverted construction method, in which the first floor floor is constructed as the leading floor. By constructing the structural columns 6 from the first ground surface 5, it is possible to assemble the structural columns 6 on the ground.

When the expanded space is filled with concrete and the structural column 6 is constructed, the structural column 6 supports the load of the above-ground structure and serves as a foundation pile capable of resisting upward tensile forces due to moments acting on the above-ground structure. For example, columnar rebar is inserted into the vertical hole-shaped space in the structural column 6. Concrete is then poured into the vertical hole-shaped space in the structural column 6, and the structural column 6 is constructed.

As shown in Figure 4, a first temporary earth retaining support 4 is installed between the opposing earth retaining walls 3. The first temporary earth retaining support 4 is constructed, for example, as a frame made up of H-shaped steel members or other components. H-shaped steel members are placed between the ends of the first temporary earth retaining support 4 and the earth retaining wall 3, along the horizontal direction of the surface of the earth retaining wall 3. The first temporary earth retaining support 4 supports the opposing earth retaining wall 3 in the axial direction, preventing the earth retaining wall 3 from bulging inward due to earth pressure. Removed objects T, such as debris and removed soil from the demolished existing underground structure 2, are removed from the ground surface using a crane device K or the like between the first temporary earth retaining support 4. The first ground surface 5 has a depth that is shallower than the groundwater level, for example.

As shown in FIG. 5, a new basement floor 7 is then constructed above the first ground surface 5. The new basement floor 7 is constructed, for example, on the first ground surface 5 and supported by the upper parts of the structural columns 6. The new basement floor 7 is constructed, for example, of reinforced concrete and can be used as a pilot floor in the inverted construction method for constructing the additional new underground structure 15 described below the first ground surface 5. When constructing the new basement floor 7, the gantry piles F3 above the first ground surface 5 are removed. The removed gantry piles F3 can be used as the second temporary earth retaining support 13 described below. A first predetermined number of new underground structures 8 are constructed above the new basement floor 7 using the forward construction method. The new underground structure 8 is constructed up to the new first floor floor 9. At this time, the first temporary earth retaining support 4 is sequentially removed. The removed first temporary retaining support 4 can be reused as the second temporary retaining support 13, which will be described later.

The new underground structure 8 is formed, for example, using a concrete injection method, and multiple temporary openings H that penetrate vertically are appropriately provided. The temporary openings H are used, for example, to transport removed materials using a crane or the like, or to transport materials for constructing the additional new underground structure 15 (described below) below the new basement floor surface 7, and to bring in and out hoses for pouring concrete. The new first floor surface 9 is constructed, for example, based on a reinforced concrete structure. Multiple temporary openings H that penetrate vertically are appropriately provided in the new first floor floor surface 9. The temporary openings H are provided, for example, in positions that are aligned vertically with the temporary openings H provided in the new basement floor surface.

The temporary opening H is used, for example, to remove debris and excavated material from the demolished existing basement floor using a crane device K, or to transport removed materials such as parts of the platform piles, or to bring in materials for constructing a new underground structure 8, or to bring in and out hoses for pouring concrete.

In this embodiment, the new underground structure 8 is, for example, two underground floors. As described above, the new underground structure 8 is constructed above the groundwater level, so a framework of guaranteed quality can be constructed without groundwater leaking. Furthermore, by preventing groundwater leaking, an increase in the load that the SMW constructing the underground diaphragm wall receives in the direction of the building's interior can be prevented, ensuring the stability of the SMW.

As shown in Figure 6A, the new underground structure 8 is then constructed. The new underground structure 8 is constructed using the sequential pouring method, ensuring a stable quality of the concrete. The temporary opening H may be closed off as necessary.

As shown in Figure 6B, an underground slope 10 connecting the new basement floor surface 7 and the new first floor floor surface 9 may be provided in part of the new underground structure 8. The underground slope 10 is constructed, for example, of reinforced concrete using the pour-in-place method, but it may also be a temporary structure that will be removed later, or it may be assembled using H-beams or the like so that it can be dismantled.

The underground ramp 10 may be constructed, for example, for each floor of the new underground structure 8, or may be constructed to connect the new basement floor surface 7 and the new first floor floor surface 9. The underground ramp 10 can be used as a vehicular passageway for transporting removed materials such as debris and excavated soil from the demolished existing basement floors, and for transporting materials for constructing the new underground structure 8.

As shown in Figure 7, after the new first floor 9 is constructed, a new ground floor 11 is constructed above the new first floor 9. Simultaneously with the construction of the new ground floor 11, the ground below the new basement floor 7 is excavated. At this time, the ground is excavated down to a second ground surface 12 at a second predetermined depth that is shallower than the first predetermined depth at which the lower ends of the structural columns 6 are located. An underground space is formed between the new basement floor 7 and the second ground surface 12, and the new basement floor 7 is supported by multiple exposed structural columns 6.

At this time, the temporary opening H is used, for example, using a crane or other device to remove excavated soil and other materials generated by excavating the ground, to bring in materials for constructing the new underground structure 8, to bring in some of the components used as the gantry piles F2 to be used as components for the second temporary earth retaining support 13, and to bring in and out hoses for pouring concrete. The gantry piles F2 are also removed sequentially depending on the depth of the excavation of the ground.

A second temporary retaining support 13 is installed between the opposing earth retaining walls 3. The second temporary retaining support 13 is constructed on a framework using, for example, the first temporary retaining support 4 and gantry piles F2. H-beams are placed between the ends of the second temporary retaining support 13 and the earth retaining wall 3, running horizontally along the surface of the earth retaining wall 3. Like the first temporary retaining support 4, the second temporary retaining support 13 supports the opposing earth retaining wall 3 in the axial direction, preventing the earth retaining wall 3 from bulging inward due to earth pressure.

If an underground slope 10 is installed, the excavated soil and other materials produced by excavating the ground can be transported to the new underground structure 8 through the temporary opening H, and then transported using vehicles or heavy machinery using the underground slope 10.

As shown in FIG. 8 , the second ground surface 12 is excavated to approximately the same height as the upper ends of the foundation piles 6A. A new additional basement floor surface 14 is constructed on top of the second ground surface 12. A second predetermined number of additional underground structures 15 are constructed sequentially above the new additional basement floor surface 14 using the sequential pouring method. In this embodiment, the second predetermined number of floors is two. That is, in this embodiment, the additional new underground structures 15 are three and four basement floors. The additional new underground structures 15 are constructed of reinforced concrete using a method such as concrete pumping. The structural columns 6 become part of the structure of the additional new underground structure 15 and are integrated with it. The foundation piles 6A support the additional new underground structures 15 and the new underground structure 8.

Furthermore, as shown in FIG. 9, an additional underground slope 16 may be constructed as part of an additional new underground structure 15. The additional underground slope 16 may be constructed, for example, for each additional new underground structure 15, or may be constructed from the new additional underground floor surface 14 to the new underground floor surface 7. The additional underground slope 16 is constructed, for example, of reinforced concrete, but may also be a temporary structural part that will be removed later, or may be assembled using H-beams or the like so as to be dismantled.

Outgoing materials such as debris are transported out from the additional underground slope 16, and incoming materials such as materials are brought in. Based on the above process, an additional new underground structure 15 is constructed between the new additional underground floor surface 14 and the new underground floor surface 7. After the outgoing materials are transported out using a crane or other device, each temporary opening H is closed. If each temporary opening H does not need to be closed, it is left in place and used as part of the additional new underground structure 15.

According to the above-described underground structure construction method, when constructing the structural columns 6 using the inverted construction method, the capitals of the structural columns 6 can be extended to the first ground surface 5, thereby shortening the length of the structural columns 6. By shortening the structural columns, there is an advantage in that the structural columns can be assembled on the ground even if the construction area 1 is narrow.

The above-described underground structure construction method allows for stable construction of the new underground structure, as it uses a pour-in-place method to construct the new underground structure from the first ground surface 5, which is higher than the groundwater level. Furthermore, by providing temporary openings H on the new first floor floor and the additional new underground structure, items can be easily transported in and out using heavy machinery. Furthermore, when constructing an additional underground slope on part of the new underground structure or part of the additional new basement floor, items can be easily transported in and out using vehicles and heavy machinery.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be modified as appropriate without departing from the spirit of the invention. For example, the underground slope 10 and the additional underground slope 16 may be designed structures, or may be temporary structures that will be removed later.

1 Construction area 2 Existing underground structure 3 Retaining wall 4 First temporary earth retaining support 5 First ground surface 6 Main column 7 New underground floor surface 8 New underground structure 9 New first floor floor surface 10 Underground slope 11 New ground floor 12 Second ground surface 13 Second temporary earth retaining support 14 New additional underground floor surface 15 Additional new underground structure 16 Additional underground slope F Platform

Claims (2)

constructing an earth retaining wall around the periphery of the existing underground structure;
removing a first predetermined number of existing basement floors below the first floor of the existing underground structure;
a step of installing a first temporary earth retaining support supporting the earth retaining wall from a first ground surface that appears after removing the existing basement floor to the height of the first floor;
constructing a plurality of structural columns from the first ground surface to a first predetermined depth below;
constructing a new underground floor surface on the first ground surface;
a step of sequentially constructing a first predetermined number of new underground structures upward from the new underground floor surface to a new first floor surface;
a step of sequentially constructing a new above-ground structure from the new first floor floor surface upward, and excavating the ground below the new basement floor surface to a second ground surface at a second predetermined depth that is shallower than the first predetermined depth;
constructing a foundation on the second ground surface;
a step of installing a second temporary earth retaining support supporting the earth retaining wall from the foundation to the height of the new basement floor surface;
a step of sequentially constructing an additional new underground structure for a second predetermined number of stories upward from the foundation;
Equipped with
The first ground surface has a depth direction height that is shallower than the groundwater level,
constructing an underground slope connecting the new underground structure of the first predetermined number of floors and the new first floor floor surface;
A method for constructing an underground structure, comprising the step of constructing an additional underground slope upward from the foundation . When the underground slope and the additional underground slope are provided in the construction of the new underground structure and the construction of the additional new underground structure, a step of transporting removed objects and transporting objects to be carried in using the underground slope and the additional underground slope is provided.
A method for constructing an underground structure according to claim 1 .