KR20200104534A - Method for constructing underground structure busing PC integrating method without support - Google Patents

Abstract

The present invention is a non-supporting top-down that improves workability and structural safety by using a factory-made PC member for the construction process of a retaining wall of the non-supporting top-down method, the construction of support beams, and the synthesis process of the internal pillars of a steel frame, and by integrating it with on-site concrete. We present the underground structure PC complex construction method.
An unsupported top-down underground structure PC complex construction method according to an embodiment of the present invention includes the steps of: (P1) constructing a retaining wall using a hollow PC wall capable of post-tensioning; (P2) installing the inner pillars of the steel frame at the location where the main pillars of the building will be installed; (P3) excavating to build a first floor deck; (P4) building a floor plate on the first floor above the ground; (P5) excavating to build a basement floor plate; (P6) installing PC struts between the inner pillars of each steel frame and between the inner pillars of the steel frame and the hollow PC wall at the basement level of the first floor base plate to support the retaining wall; (P7) constructing a basement floor slab; (P8) repeating the steps of (P5) to (P8) for constructing a floor plate by excavating one basement floor and installing PC support on the floor; (P9) assembling a reinforced reinforcing bar-integrated PC formwork on the outside of the inner pillars of the steel frame of the entire basement floor, and placing concrete from the first floor floor plate to simultaneously construct the internal pillars of the entire basement floor as SRC columns; And (P10) excavating the bottom of the bottom layer and constructing the bottom plate of the bottom layer.

Description

Method for constructing underground structure busing PC integrating method without support}

The present invention relates to a construction method for the construction of an underground structure, and more particularly, a PC member manufactured in the factory is used for the construction of an unsupported top-down construction method, a support construction process, and a synthesis process of an inner column of steel frame It relates to a PC-combined construction method for an unsupported top-down underground structure that is integrated with concrete to improve constructability and structural safety.

In recent years, in narrow urban areas, high-rise and large-sized buildings are being constructed in close proximity to the site boundary line to secure high land prices, secure parking spaces, and maximize site utilization.

Against this background, among the methods developed so that construction can be performed without adversely affecting the surrounding ground when constructing an underground structure as a construction method suitable for urban construction, many top-down construction methods that can be safely implemented are applied.

Top-Down construction method (top-down construction method, reverse punching method) means that after first constructing the earth wall, then constructing the pillars and the foundation, the ground work can be carried out at the same time while gradually building the basement layer from the floor slab on the first floor. In the substructure construction, a diaphragm wall (slurry wall) is constructed to prevent subsidence of nearby ground and buildings, and damage to underground buried materials, and excavation to build an underground structure after construction. Is a construction method developed to expect stability during underground construction and the effect of shortening the total air by constructing a superstructure construction while excavating from the first floor below the ground. This construction method is widely applied to large-scale building construction in urban redevelopment projects such as close-up construction, large-distance excavation, close-up site and narrow work area.

Since this construction method first constructs the first floor above the ground, it can be used as a work place, so it is advantageous to carry in and out of vehicles and place materials when constructing in a dense urban area, and a high-stiffness diaphragm wall (slurry wall) is used to make the surrounding ground. Since it minimizes the effects of subsidence and building subsidence, it is possible to perform underground construction structurally and safely during construction. In addition, since it is possible to construct the ground frame separately from the excavation work, the total air can be shortened as much as the underground excavation air, and since the underground excavation work is carried out after pre-construction of the first floor above the ground, it is hardly affected by the climate, so it is an accurate process. Management is possible, and it is possible to proceed smoothly by preventing civil complaints such as noise and vibration.

Recently, the non-holding top-down construction method has been studied and constructed as a type of top-down construction method. If the conventional top-down construction method is a supporting method using copper bars (SOS construction method), the non-holding top-down construction method is conventional. It is a construction method that has dramatically improved the shortcomings of the top-down construction method in the building and solves the work waiting during the concrete curing period, and simplifies the repetitive installation, dismantling, transportation, and lifting processes of movable bars and forms. In addition, it contributes to the improvement of the environment by minimizing the disposal and discharge of discarded concrete and mold remnants, and it is also effective in improving safety due to the problem of the earthwork work area and the structure work area.

Therefore, it is necessary to continue the invention of various non-holding top-down construction methods in the future.

As a background technology of the present invention, there is Patent Registration No. 10-0775767'The reverse casting construction method using vertical reinforcing bars of the SRC frame' (Patent Document 1). This patent proposes a reverse casting construction method that is advantageous for improving workability and reducing materials by using vertical reinforcing bars for columns of SRC frames in constructing a multi-story underground structure by lowering the beam-slab suspension form step by step. However, this patent uses a beam-slab suspension formwork to construct a beam and a slab in an on-site concrete structure, and it has the advantage of saving material and securing the integrity between members by repeated use of the beam-slab suspension form. There is a disadvantage in that the construction is delayed because the lower floor work cannot be performed until the amount of cast-in-place concrete is increased and the beam-slab concrete in the upper floor is cured.

Another technology that serves as the background of the present invention is Patent Registration No. 10-0788623'Top-down method using PC pillars' (Patent Document 2). This patent proposes a top-down construction method using PC columns instead of steel columns as columns that are pre-embedded in the ground in the previous top-down construction method. However, this patent has disadvantages in that it is difficult to secure the integrity between the upper and lower PC pillars in the basement, and the workability of the joint between the PC pillar and the steel beam supporting the earthen barrier is poor.

Patent Registration No. 10-0775767'Reverse casting construction method using vertical reinforcing bars of SRC frame' Patent Registration No. 10-0788623'Top-down method using PC pillars'

The present invention makes full use of the advantages of the conventional unsupported top-down method, while making half-precast concrete (partial PC) of the main structural members used for earth protection, and pouring in-situ concrete and integrating these members for constructability and structural stability. Its purpose is to provide a PC-combined construction method for an unowned top-down underground structure that can secure the structure.

An unsupported top-down underground structure PC complex construction method according to a preferred embodiment of the present invention includes the steps of: (P1) constructing a retaining wall using a hollow PC wall capable of post-tensioning; (P2) installing the inner pillars of the steel frame at the location where the main pillars of the building will be installed; (P3) excavating to build a first floor deck; (P4) building a floor plate on the first floor above the ground; (P5) excavating to build a basement floor plate; (P6) installing PC struts between the inner pillars of each steel frame and between the inner pillars of the steel frame and the hollow PC wall at the basement level of the first floor base plate to support the retaining wall; (P7) constructing a basement floor slab; (P8) repeating the steps of (P5) to (P8) of excavating a basement layer and installing a PC support on the floor to construct a floor plate for each basement floor; (P9) assembling a reinforced reinforcing bar-integrated PC form on the outside of the inner pillars of the steel frame on the entire basement floor, and placing concrete on the first floor deck to construct the internal pillars of the entire basement floor as SRC columns at the same time; And (P10) excavating the lowermost floor and constructing the lowermost floor plate.

The hollow PC wall capable of post-tensioning in the step (P1) includes a PC wall fixing member that connects the first PC plate and the second PC plate positioned in parallel, and the first PC plate and the second PC plate by a predetermined distance, It includes a U-shaped sheath pipe inserted between the first PC plate and the second PC plate, and the first PC plate has a buried plate installed at a joint position with the PC brace, and the second PC plate has a truss muscle installed on one side. It is a PC plate, and concrete is poured between the first PC plate and the second PC plate to form an earth barrier, and it is characterized in that post tension is possible through a U-shaped sheath tube.

In addition, in step (P6), the brackets are bonded to the buried plate of the steel inner pillar and the hollow PC wall, respectively, to fix the PC brace between the steel inner pillars and between the steel inner pillar and the hollow PC wall. It characterized in that it comprises a lower plate that provides a size to support and a pair of web plates that connect the upper and lower plates and the upper and lower plates of the size to fix the position of the PC support and the shear key is installed to protrude outward.

In addition, in step (P6), the PC support beam is a factory-made PC beam, and its end is manufactured in a C shape, and has an opening that facilitates assembly and on-site concrete placement.

In addition, the reinforcing bar-integrated PC formwork in step (P9) is a reinforcing bar-integrated PC formwork including a PC plate and an integral reinforcing bar, which is assembled outside the inner pillar of the steel frame, and forms a part of the SRC column after the concrete is poured and cured. .

The non-supported top-down PC complex method according to the present invention utilizes the advantages of the conventional non-supported top-down method, while making half precast concrete (partial PCization) of the main structural members used in the soil barrier construction, and pouring on-site concrete. By integrating these members, there is an effect of securing workability and structural stability.

The following drawings appended in the present specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of the present invention together with the detailed description of the present invention, so the present invention is limited to the matters described in the accompanying drawings. It is limited and should not be interpreted.
1 is a cross-sectional view schematically showing the construction sequence of the non-holding top-down underground structure PC complex construction method according to the present invention.
2 is a diagram showing a hollow PC wall capable of post tension applied to the present invention, 2a is a view showing an installation state of the hollow PC wall, and 2b is a perspective view showing the components of the hollow PC wall.
Figure 3 is a perspective view showing a PC support applied to the present invention.
Figure 4 is a perspective view showing a bracket applied to the X-shaped bracket of the present invention.
5 is a perspective view showing a state of one basement layer constructed according to the present invention.
6A and 6B are perspective views showing a state in which a PC formwork is installed in order to configure the inner pillars of the steel frame into the main pillars of the steel frame reinforced concrete structure.

In the following, the present invention will be described in detail with reference to the embodiments shown in the accompanying drawings, but the disclosed embodiments are illustrative for a clear understanding of the present invention, and the present invention is not limited thereto.

The PC complex construction method for a non-supported top-down underground structure according to the present invention introduces a PC complex construction method such as the conventional soil barrier construction process, the support construction process, and the synthesis process of the steel frame inner pillars to reduce the amount of on-site concrete work. It was developed to significantly shorten the construction period by reducing it, and the entire process is similar to the conventional top-down construction method. Therefore, in the following, the characteristic process of the present invention that is distinguished from the conventional non-holding top-down method will be mainly described.

The basic component of the top-down construction method is a retaining wall to support transverse earth pressure, water pressure, and vertical load during excavation work, and is installed between the facing earth retaining wall to transmit lateral pressure acting on one retaining wall to the other retaining wall. It prevents buckling by reducing the length of the transverse support used as the beam of the underground structure and the unsupported length of the transverse support after completion of the excavation work, and transfers the load of the upper structure based on the load of the upper structure. It is an inner pillar used as a pillar.

In the present invention, a precast concrete wall (hereinafter referred to as a hollow PC wall) 10 is adopted as a retaining wall by adopting an underground continuous wall method, but post tension is possible and on-site concrete pouring is possible. After completion, it should be used as a permanent wall (outer wall) of an underground structure. In addition, when constructing the floor, a non-support method is introduced, but precast concrete beams (hereinafter referred to as PC braces) 30 are used instead of H-beams used as ordinary transverse supports. In addition, by using a form (hereinafter referred to as PC form) composed of precast concrete plate integrated with reinforced reinforcement (hereinafter referred to as PC form) (60), the inner column of the steel frame is composed of a steel frame reinforced concrete (hereinafter referred to as SRC) composite column.

1 is a cross-sectional view schematically showing the construction sequence of the non-holding top-down underground structure PC complex construction method according to the present invention.

As shown in Fig. 1, the non-supporting top-down underground structure PC complex construction method according to the present invention comprises the steps of (P1) constructing a retaining wall using a hollow PC wall 10 capable of post tension (a); (P2) Step (b) of installing the steel frame inner pillar 20 at the location where the main pillar of the building will be installed; (P3) (c) excavating to build the first floor above the ground; (P4) Step (d) of constructing a first floor above the ground; (P5) Excavating for installation of the first basement floor (d); (P6) Step of supporting the retaining wall by installing PC struts 30 between the inner pillars of each steel frame 20 and between the inner pillars of steel frame 20 and the hollow PC wall 10 at the basement level of the first basement floor plate (e ); (P7) constructing the first basement floor slab (f); (P8) repeating the steps (P5) to (P8) of excavating one basement layer and constructing a slab by installing PC struts on the floor (g); (P9) Assembled reinforced reinforced integrated PC formwork (60) on the outside of the steel internal pillars (20) on all basement floors, and poured concrete from the first floor deck to form the internal columns (20) of all basement floors simultaneously as SRC columns. Step (g); And (P10) excavating the bottom of the bottom layer and constructing the bottom plate of the bottom layer (h).

Hereinafter, each step of the non-holding top-down underground structure PC complex construction method according to the present invention will be described in detail.

1. (P1) Stage-Construction of earth barrier wall

In the top-down construction method, since the retaining wall has to support vertical loads in addition to the main role of supporting transverse soil pressure and water pressure, the Diaphragm Wall (Slurry Wall) is mainly used.

First, the ground is excavated using a conventional excavator at a required depth in consideration of the outer boundary line where the underground structure will be formed according to a specific actual design, and then a stabilizer made of bentonite is injected into the excavation space.

Subsequently, as shown in FIG. 2A, a precast concrete wall (hereinafter referred to as a hollow PC wall) 10 manufactured in a factory capable of post-tensioning is continuously inserted in the excavation space into which the stabilizing solution is injected in a vertical direction to form a retaining wall.

The hollow PC wall 10 applied to the present invention shown in FIG. 2B is manufactured in a factory, and the first PC plate 11 and the second PC plate 12 of the hollow PC wall are located in parallel, and the first PC wall fixing members 13 that connect the PC plate 11 and the second PC plate 12 by a predetermined distance are installed at regular intervals in the length direction of the PC plate. The first PC plate 11 used as the outer wall of the underground structure is provided with a buried plate 15 at a position for coupling with the PC support 30 to be described later (see Fig. 1A). The second PC plate is a half PC plate having a truss root installed on one side, and a U-shaped sheath tube 14 for post tension is inserted between the first PC plate 11 and the second PC plate 12. The position of the buried plate 15 is factory-made by calculating the joint position with the PC support 30, but considering the error, the size is made larger than the end size of the PC support 30.

After the hollow PC wall 10 is continuously inserted, concrete is poured between the first PC plate 11 and the second PC plate 12 of the hollow PC wall 10 to form a continuous barrier wall. Some of the stabilizing liquid injected in the above process is recovered, and the concrete pouring method and the stabilizing liquid recovery method may be arbitrarily selected from methods known in the art.

After the concrete is cured, the PS stranded wire 16 in the U-shaped sheath 14 installed inside the hollow PC wall 10 is tensioned by a known method to introduce prestress to the retaining wall.

The soil barrier wall using the hollow PC wall 10 installed at this stage can realize the high-strength wall required as an underground structural wall rather than a simple soil barrier compared to the conventional underground continuous wall, and the first PC plate 11 is a finishing wall. As it can be used as a hollow PC wall 10 is manufactured in a factory, assembly is easy and site installation is simple. In addition, it is possible to significantly reduce the thickness of the wall by post-tensioning, and it is resistant to cracking moments caused by earth pressure, so that cracking can be prevented.

2. (P2) Step-Install the inner pillars of the steel frame

This step is a step of drilling the position where the main pillar of the building is to be installed by a conventional method and installing the inner pillar 20 of the steel frame.

In the plan design of the building, the inner pillar of the steel frame is inserted vertically from the ground into the perforated hole at the position where the pillar as the main structure is to be installed, and then the foundation is formed at the lower end of the inner pillar 20 of the steel frame. In the present invention, the inner pillar 20 of the steel frame is connected to a transverse support that transmits lateral pressure such as earth pressure and water pressure acting on the earth wall to the other earth wall during the basement layer construction, and serves as a center pile to resist earth pressure, After the underground work is completed, it acts as a pillar, the main structure of the building that transmits the axial force from the top to the foundation. A foundation part is formed at the lower end of the steel frame internal pillar 20 installed as above so as to transmit the load from the upper structure to the ground, and as a method of forming the foundation, a pile foundation method for temporary or permanent columns in the top-down method. Widely applied RCD (Reverse Circulation Drill), PRD (Percussion Rotary Drill), Barrette Pile method can be applied.

3. (P3) Stage-Excavation for construction of the first floor above the ground

After the retaining wall and the inner pillar of the steel frame are installed in the ground as described above, the first digging is performed on the inner soil of the retaining wall. At this time, it is preferable to excavate only the minimum depth at which the beam-slab structure can be poured on the first floor above the ground without excavating more than necessary.

4. Step (P4)-Constructing the first floor above the ground

When the 1st excavation is completed as above, construct the ground level 1st floor excluding the work area at the ground level. At this time, the first floor above the ground can be used as a workplace where vehicles can be brought in and out of the ground and material stocking is advantageous during construction, and since it is hardly affected by the climate during underground construction, accurate process management is possible, and it plays a role in preventing civil complaints such as noise and vibration.

5. (P5) Step-Excavation for installation of the first basement floor

In this step, after the ground floor is constructed, the basement floor is excavated to build the basement floor. The soil inside the retaining wall is excavated to the depth of the basement 1st floor to allow the PC support and slab structure to be poured, and the excavated soil is carried out through the work hole of the 1st floor slab above the ground.

6. (P6) Step-Installing PC struts between each inner pillar and between the inner pillar and the hollow PC wall at the basement level of the first floor.

During top-down construction, the transverse support receives moment and shearing force by its own weight, wall load, finish load, and working load, and axial pressure by transverse earth pressure and water pressure from the retaining wall. The conventional transverse support is composed of steel frame or RC tank, and depending on the method of forming the floor structure, the top-down method is largely conventional, BRD (Bracket Supported RC Downward), NSTD (Non Supporting Top Down), SPS (Strut as Permanent System). (New Technology No. 294, Samsung), etc.

In the present invention, a support beam corresponding to the basement main structure is used as a transverse support, and during excavation construction, it is used as a main structural member in the main structure without disassembling it, but not dismantled during frame construction, which is a disadvantage of the conventional construction method. Risks arising during construction such as installation or dismantling, deterioration in constructability due to mutual interference with this structure, and material loss are improved. In addition, since the material cost is high and the supply and demand of materials is not stable, a PC strut 30 is introduced instead of the steel frame, which is a factor in the construction cost increase to establish a transverse support.

The PC support 30 shown in FIG. 3 is an example, and the size or shape of the cross-section is not limited to that shown in FIG. 3. The PC support 30 has a U-shaped end thereof and provides an opening 31 of a certain space, which facilitates assembly when combined with a retaining wall or an inner pillar as described below, and facilitates on-site concrete pouring. Therefore, the purpose is to make the rigidity of the joint part sufficient.

The ㅍ-shaped connecting member (hereinafter referred to as "ㅍ bracket") 40 shown in Fig. 4a is the connection between the steel frame inner pillar and the PC brace 30 installed in step (P2), and the retaining wall and the PC brace installed in step (P1) As a means for connection with (30), its shape is the lower plate 41 providing a size to support the lower end of the PC support 30 and the PC support for connection between the PC support 30 and the retaining wall or the inner pillar. It includes a pair of webs 43 that connect the upper plate 42 and the upper and lower plates 41 and 42 of a size capable of fixing the position of the plurality of shear keys 44 to protrude outward.

As shown in Fig. 4b, the bracket 40 installed on the weak axis of the inner column further includes a rear plate 45 that can be joined to the flange 21 and 22 rather than the web 23 of the inner column 20. Can include.

After the brackets 40 are bonded to the strong and weak shafts of the inner pillars and the buried plate 15 of the hollow PC wall 10, the PC struts 30 are placed between the inner pillars 20 and the inner pillars 20. It is located between the hollow PC wall (10).

7. (P7) Step-Placing the floor slab on the first basement floor

The first basement floor slab 50 is poured. Flat slab or wide beam slab system is preferable for the non-supporting top-down method, but there is no restriction on the slab system constructed according to the structural design. However, as shown in FIG. 5, when the slab 50 is poured, each opening 51 is left at a portion corresponding to the corner of the inner column. The opening 51 is used for the installation of the connecting rod and pouring concrete when the inner column to be described later is configured as a column of SRC structure.

8. (P8) Step-Repeated backstroke construction

This step is a step of excavating the lower part of the slab, and repeating the steps (P5), (P6) and (P7) until a predetermined basement layer is formed.

9. (P9)-The step of assembling the reinforced reinforcing bar-integrated PC form on the outside of the internal pillars of the pre-construction steel frame, and pouring concrete from the first floor floor plate to simultaneously construct the inner pillars (20) of the entire basement floor as SRC pillars

This step is a process of constructing an SRC column by installing a reinforcing reinforcing bar-integrated PC formwork 60 outside the steel frame inner column 20 installed in step (P2), and a PC formwork made of a PC board instead of the existing wooden formwork. 60) is used as the main structure without removing the formwork after curing the concrete using 60), and this eliminates the step of removing the formwork and has the advantage of easy assembly.

The PC formwork 60 shown in FIG. 6A is an integrated PC formwork 60 that includes an integrated reinforcing bar 62 that is placed at the time of manufacture of the PC plate in addition to the PC plate 61, and does not require on-site placement and its assembly is simple. .

As shown in Fig. 6b, the connection main root 63 and the PC formwork 60 are assembled, and the field formwork 64 is installed on the top thereof, and concrete is poured through the opening 51 made in the slab in step (P6).

When constructing the internal pillars of the steel frame as SRC pillars using the PC formwork (60), it can be constructed in units of each floor, but by pouring concrete from the first floor above the ground, the internal pillars (20) of the entire basement floor are simultaneously constructed as SRC pillars. It is desirable to do.

10. (P10) Step-Excavating the bottom of the bottom floor and constructing the bottom plate

This step is a step of excavating the bottom surface of the lowermost layer of an underground structure and constructing the lowermost floor plate by a conventional method.

As described in detail above, the PC complex construction method for a non-supported top-down underground structure according to the present invention fully utilizes the advantages of the conventional non-supported top-down construction method, while making the main structural members used in the soil barrier construction half precast concrete (partial PC It has the effect of securing workability and structural stability by integrating these members by pouring on-site concrete.

Until now, the present invention has been described in detail with reference to the presented embodiments, but those of ordinary skill in the art can make various modifications and modifications without departing from the technical spirit of the present invention with reference to the presented embodiments. will be. The present invention is not limited by such modifications and variations of the invention, but is limited by the claims appended below.

10: hollow PC wall 11: 1st PC board
12: second PC plate 13: PC wall fixing member
14: U-shaped sheath tube 15: Embedded Plate
16: PS stranded wire 20: steel frame inner column
21: the first flange of the steel inner column 22: the second flange of the steel inner column
23: web of steel inner pillar 30: PC support PC support
40: ㅍ-shaped bracket 41: lower plate of ㅍ-shaped bracket
42: the upper plate of the letter bracket 43: the web of the letter bracket
44: Shear key of the square bracket 45: Back panel of the square bracket
50: slab 51: opening of the slab
60: PC die 61: PC version of PC die
62: integrated main muscle of PC formwork 63: connecting main muscle
64: field formwork

Claims (5)

(P1) constructing a retaining wall using a hollow PC wall 10 capable of post-tensioning;
(P2) installing the steel frame inner pillar 20 at the position where the main pillar of the building will be installed;
(P3) excavating to build a first floor deck;
(P4) building a floor plate on the first floor above the ground;
(P5) excavating to build a basement floor plate;
(P6) installing a PC strut 30 between each steel frame inner pillar 20 and between the steel inner pillar 20 and the hollow PC wall 10 at the basement level of the first floor base plate to support the earth barrier;
(P7) constructing a basement floor slab;
(P8) repeating the steps of (P5) to (P8) of excavating a basement layer and installing a PC support on the floor to construct a floor plate for each basement floor;
(P9) Assemble reinforced reinforcing bar-integrated PC formwork (60) on the outside of the steel-frame inner pillars (20) on all basement floors, and pour concrete from the first floor deck to build the internal pillars (20) of all basement floors as SRC columns at the same time. Step to do; And
(P10) Excavating the bottom of the bottom floor and constructing the bottom plate of the bottom floor; Non-holding top-down underground structure PC complex construction method comprising a. The method according to claim 1,
The hollow PC wall 10 capable of post tension in step (P1),
A PC wall fixing member 13 that couples the first PC plate 11 and the second PC plate 12 and the first PC plate 11 and the second PC plate 12 positioned in parallel by a certain distance apart, It includes a U-shaped sheath tube 14 inserted between the first PC plate 11 and the second PC plate 12,
The first PC plate 11 is equipped with a buried plate 15 at the joint position with the PC support 30, and the second PC plate is a half PC plate with a truss root installed on one side, and the first PC plate and the second PC plate A non-supporting top-down underground structure PC complex construction method, characterized in that concrete is poured between them to form a barrier wall, and post-tension is possible through a U-shaped sheath pipe (14). The method according to claim 2,
In step (P6), the bracket 40,
PC struts 30 are bonded to the steel inner pillars 20 and the buried plate 15 of the hollow PC wall 10, respectively, and between the steel inner pillars 20 and between the steel inner pillars 20 and the hollow PC wall 10. ),
The lower plate 41 that provides the size to support the lower end of the PC support 30 and the upper plate 42 and the upper and lower plates 41 and 42 of the size that can fix the position of the PC support are connected, and a shear key ( A non-supporting top-down underground structure PC complex construction method, characterized in that it comprises a pair of web plates 43 installed to protrude outwardly. The method of claim 3,
In step (P6), the PC support 30,
A factory-made PC beam, the end of which is manufactured in a c-shape, and has an opening that facilitates assembly and on-site concrete placement. The method according to claim 1,
In step (P9), the reinforcing bar integrated PC form (60),
It is a reinforced integrated PC formwork 60 including a PC plate 61 and an integral reinforcing bar 62, which is assembled on the outside of the steel inner column 20 to form a part of the SRC column after the concrete is poured and cured. Top-down underground structure PC complex construction method.

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