JP5541520B2 - Underground construction - Google Patents

Description

  The present invention relates to an underground construction method applied to the construction of a building having a plurality of floors.

  As an underground construction method for constructing a building on the basement floor of a building, for example, a reverse driving method as shown in Patent Documents 1 and 2 is known. In this method, a temporary construction column is built prior to ground excavation, and then the underground structure is constructed from the upper layer to the lower layer while excavating the ground step by step.

JP-A-6-146303 Japanese Patent No. 2964295

  In the above-described conventional back-strike method, a temporary construction pillar made of a steel frame such as an H-shaped steel is provided, so that such temporary work requires considerable effort and cost, and is not always reasonable. There is room for improvement.

  In view of the above circumstances, an object of the present invention is to provide an effective and appropriate underground construction method capable of efficiently constructing a basement frame without using a temporary construction stem.

  In the construction of the first aspect of the present invention, when constructing a building having a plurality of basement floors, an arbitrary basement floor in the upper part of the basement floor or the first floor above the ground is set as a preceding construction floor, It is an underground construction method in which the skeleton is preceded by a lower basement skeleton, and after the foundation is excavated to form the foundation bottom, the main pillar reaches the preceding construction floor on the foundation bottom. The PCa pillar is constructed in a self-supporting state, and the preceding construction floor frame is preliminarily constructed on the upper part of the PCa pillar, and then the preceding construction floor is constructed while the upper floor structure is constructed above the preceding construction floor. In the lower part of the floor, a basement floor structure lower than the preceding construction floor is constructed following the work from the foundation bottom.

  The invention according to claim 2 is the underground construction method according to claim 1, characterized in that the PCa pillar is constructed by connecting in advance the unit PCa pillar of a predetermined length manufactured in advance in the axial direction.

  Invention of Claim 3 is the underground construction method of Claim 1 or 2, Comprising: The said PCa pillar is formed with high-strength concrete.

  The invention according to claim 4 is the underground construction method according to claim 1, 2, or 3, wherein the building to be constructed is a base-isolated structure building having a base-isolated floor on the upper part of the basement or the ground floor, The seismic isolation floor is set as the preceding construction floor.

According to the underground construction method of the present invention, the temporary PCa column is constructed at an early stage without constructing a temporary construction column as in the conventional general reverse driving method, so that the temporary construction can be greatly reduced and the efficiency is improved. The construction of the entire building can be greatly improved since the construction of the upper floor and the construction of the lower floor can be carried out simultaneously and concurrently after the construction of the preceding construction floor. It can contribute to reduction of construction cost and construction period.
Of course, the PCa column installed as a permanent installation can have sufficient buckling strength even if it has a small cross section compared to a steel frame such as H-shaped steel used as a temporary construction true column. Therefore, it is possible to ensure the safety and reliability sufficiently when the upper layer is preceded by the lower layer of the basement.

The embodiment of the underground construction method of this invention is shown, and is a figure which shows schematic structure of the underground frame which should be constructed. It is a figure which shows the construction procedure of an underground frame. It is a figure which shows the construction procedure of an underground frame.

Embodiments of the present invention will be described below with reference to FIGS.
The building to be constructed in this embodiment is a three-story high-rise base-isolated building (the number of floors on the ground floor is arbitrary). As shown in FIG. The beam 1 is composed of a lower beam 1a and an upper beam 1b, and a seismic isolation device (laminated rubber) 1c is installed between them.

  The underground construction method of this embodiment is to set up the first basement floor, which is a seismic isolation floor, as the preceding construction floor when constructing the building from the third basement floor to the first basement floor in the above-mentioned building. The construction is prior to the beams on the second and third floors, and for that purpose, the main purpose is to construct the PCa pillars (precast concrete pillars) 10 as the main pillars on the respective underground floors in an independent state at an early stage.

  That is, in this embodiment, after excavating the construction area of the entire underground floor, as shown in FIG. 2 (a), the foundation bottom 4 is constructed by a normal method, and as shown at (b) to (e) at that time. The pre-construction of the main PCa column 10 is carried out in a self-supporting state.

In the present embodiment, the PCa column 10 has a predetermined length of unit PCa columns 10a connected in the axial direction (four in the illustrated example) to reach the lower beam 1a on the first basement floor from the foundation bottom plate 4, The whole functions as a pillar of the underground floor and has sufficient buckling strength from the construction stage as well as after the building is completed.
In the present embodiment, each unit PCa column 10a is formed of high-strength concrete, and as shown in FIG. 1, a column main reinforcement 11 is embedded in each unit PCa column 10a in advance, and the column main reinforcement. 11 is protruded slightly upward, and a reinforcing bar joint 12 into which the upper end of the column main reinforcement 11 of the lower PCa column 10a is inserted is embedded in advance at the lower end of each unit PCa column 10a. good.

In addition, a basement beam is joined to the middle portion of the PCa column 10 at a later stage. In the illustrated example, the four unit PCa columns 10a are connected to the upper part of the third unit PCa column 10a from the bottom. Since the RC beam as the beam 2 on the second basement floor is joined, a reinforcing bar 13 which is connected to the beam main reinforcing bar 2a and becomes a part thereof is embedded in advance at the joining position, and shear force is transmitted to the joining surface. A cotter 14 may be formed in advance.
Further, since the lower beam 1a of the first basement, which is the preceding construction floor, is joined to the uppermost unit PCa column 10a, the column main reinforcing bar 11 is projected largely upward and a fixing plate is attached to the tip thereof. It is preferable to fix firmly to the lower beam 1a.

In order to erect the above-mentioned PCa pillar 10 on the foundation bottom board 4, as shown in FIG. 2 (a), when constructing the foundation bottom board 4, the anchor bars 4a are embedded in advance in the standing position of the PCa pillar 10. Keep it.
Although it is usually sufficient that the foundation base 4 is made of ordinary concrete, high-strength concrete is cast at least at the joint with the PCa column 10 (for example, the hatched range in FIG. 1) to form the PCa column 10. It is preferable to have the same strength as the above.

And after connecting the four unit PCa pillar 10a sequentially as shown in FIG.2 (b)-(e) and constructing the PCa pillar 10 whole in a self-supporting state, as shown in FIG. The lower beam 1a in the first basement, which is the floor, is integrally constructed on the column head of the PCa column 10.
As the lower beam 1a, it is sufficient to use an RC beam made of ordinary concrete. However, since the joint with the PCa column 10 (range shown by hatching in FIG. 1) also functions as an installation base for the seismic isolation device 1c, at least The portion is preferably made of high strength concrete and has the same strength as the PCa pillar 10.
After that, as shown in (b), after installing the seismic isolation device 1c on the lower beam 1a, the upper beam 1b is constructed and the first floor basement is pre-constructed.

  Now that the construction of the first floor basement as the preceding construction floor has been completed, the pillar 5 of the first basement, which is the upper floor of the upper floor, will be constructed. Afterwards, the lower basement frame will be installed. That is, the beam 2 on the second basement floor may be constructed as shown in (c) by work from above the foundation bottom board 4, and then the beam and floor (not shown) on the third basement floor may be sequentially constructed.

According to the underground construction method of the present embodiment, the temporary PCa column 10 is constructed at an early stage without constructing a temporary construction true pillar as in the conventional reverse driving method, so that the temporary construction can be greatly reduced. The construction of the upper floor and the lower floor can be performed by simultaneous parallel work after the previous construction floor has been constructed. It can greatly improve and can contribute to reduction of construction cost and construction period.
Of course, the PCa column 10 to be installed as a permanent installation can have a sufficient buckling strength even if it has a small cross section compared to a steel frame such as an H-shaped steel used as a temporary construction column. The PCa pillar 10 itself can be made to be sufficiently stable and independent without the need for support, and therefore sufficiently secure safety and reliability when the upper part of the basement is preceded by the lower part. Can do.

  In addition, by forming the PCa pillar 10 with high-strength concrete as in the above embodiment, the buckling strength can be further increased as compared with the case of ordinary concrete, and a sufficiently small cross section can be achieved. The PCa column 10 is not necessarily made of high-strength concrete, and may be designed to ensure a desired buckling strength by the PCa column 10 made of ordinary concrete.

Further, when installing the PCa pillars 10, it is practical to sequentially connect the unit PCa pillars 10a having a predetermined length as in the above-described embodiment in consideration of the carrying-in work and the construction process. The length of each unit PCa column 10a and the number of connected units may be optimally set in consideration of the height of the underground floor, the specifications of the hoist and other work conditions, and for joining the unit PCa columns 10a to each other. The structure and the structure for joining the PCa pillar 10 to the foundation bottom 4 and the basement beam are also arbitrary.
Of course, the PCa pillar 10 is not necessarily constructed by connecting the unit PCa pillars 10a. In the case where the total height of the basement floor is not so large, the long PCa over the entire height of the basement floor to be preceded by construction. It is not impossible to stand up the entire column 10 at once.

Furthermore, since the above embodiment is intended for buildings with the base isolation floor as the first basement floor, the basement first floor is set as the preceding construction floor, but usually the base isolation floor is the first floor above ground. In this case, it is realistic to set the preceding construction floor as the first floor above the ground. However, in the present invention, the seismic isolation floor is not necessarily limited to the preceding construction floor, and the preceding construction floor may be set to any one of the upper part of the basement floor or the first floor above the ground floor.
Of course, in the underground construction method of the present invention, it is only necessary to construct a plurality of basement columns as the main PCa column 10 at an early stage, and so long as the present invention is applied to the construction of a non-base-isolated building. Needless to say, the structural form of the entire building is arbitrary as well as being possible, and it can be widely applied when constructing buildings of various scales and uses.

1 Liang (basement 1st floor)
1a Lower beam 1b Upper beam 1c Seismic isolation device (laminated rubber)
2 Beams (2nd basement frame)
4 Foundation floor 4a Anchor muscle 5 Pillar (upper frame)
10 PCa column 10a Unit PCa column 11 Column main bar 12 Reinforcement joint 13 Reinforcement 14 Cotter

Claims (4)

When constructing a building having a plurality of basement floors, an arbitrary basement floor in the upper part of the basement floor or the first floor above the ground is set as a preceding construction floor, and the frame of the preceding construction floor is below the basement. It is an underground construction method that precedes the building on the floor,
After excavating the ground to form the foundation bottom, the PCa pillar as the main pillar reaching the preceding construction floor is constructed on the foundation bottom in a self-supporting state, and the frame of the preceding construction floor is formed above the PCa pillar. As a one-piece construction,
After that, while constructing the upper-floor frame from the preceding construction floor, the lower-floor basement floor below the preceding construction floor is constructed downstream from the foundation floor. An underground construction method characterized by that. The underground construction method according to claim 1,
An underground construction method, wherein the PCa pillar is constructed by connecting in advance the unit PCa pillar having a predetermined length, which is produced in advance. The underground construction method according to claim 1 or 2,
An underground construction method characterized in that the PCa pillar is formed of high-strength concrete. The underground construction method according to claim 1, 2, or 3,
A basement construction method characterized in that the building to be constructed is set as a base-isolated structure in which the upper part of the basement floor or the first floor above ground is a base-isolated floor, and the base isolation floor is set as the preceding construction floor.

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