KR101331261B1 - Underground prefabricated precast concrete rainwater recycling facility using precast concrete continuous wall in strut structure or earth anchor and construction method of the same - Google Patents

Abstract

The present invention relates to an underground prefabricated precast concrete (PC) rainwater recycling facility for a strut or earth anchor structure using an underground PC continuous wall which has excellent waterstop and reinforcement effects for the edge part where the underground PC continuous wall meets a bottom slab and a construction method for the same to use a temporary facility wall as a permanent structure and to install the temporary facility wall and a structure wall on the same line. A construction method for a PC rainwater recycling facility according to a proper embodiment of the present invention comprises a step of installing a guiding wall on the top of an underground continuous wall to be constructed; a step of trench-excavating a space between the guiding walls facing each other using excavation equipment, injecting a stabilizer liquid into the excavation hole, and maintaining a hollow wall; a step of installing a PC panel to be connected to the excavation hole, installing a grouting water stop between neighboring PC panels, performing joint grouting, and sealing an outer wall part with high density cement-bentonite in order to build the underground continuous wall; a step of excavating the ground of an area surrounded by the PC panels and supporting the excavated area with struts; a step of placing lean concrete onto the bottom surface of the excavated area and placing foundation concrete on the top of the lean concrete placement to build the bottom slab; a step of setting up a plurality of PC columns on the top of the bottom slab and installing a PC beam at the top of each PC column so that the PC beam supported in the PC panel is placed at the groove on the top of the PC panel; and installing a PC slab on the top of the PC beam and placing topping concrete.

Description

Underground prefabricated precast concrete rainwater recycling facility using precast concrete continuous wall in strut structure or earth anchor and construction method of the same}

The present invention relates to a PC storage tank and a construction method thereof, and in particular, the wall can be used as a permanent structure after using the wall as a temporary wall, and the temporary wall and the structural wall are constructed on the same line, where the PC underground wall and the floor slab meet. The present invention relates to an underground PC storage tank and a construction method thereof that can be constructed in strut structures or earth anchor structures by using PC underground continuous walls having excellent index and reinforcement effects at edges.

Reservoir is a facility that can collect rainwater during rain or flood to cope with water shortage and flood damage, and can be used as living water, cleaning water, fire water, landscaping water.

There are concrete storage tanks and plastic storage tanks.In the case of concrete storage tanks, on-site concrete-type storage tanks in which concrete is formed by placing concrete at the construction site and each component made in advance in the factory are transported and assembled. There is a precast concrete (PC or PC) storage tank.

In the case of cast-in-place concrete storage tank, it is the oldest storage method, but it has a long construction period and it is difficult to secure quality. In the case of PC storage tank, there is an advantage that the construction is completed only by the assembly without the curing period.

As a background technology of the present invention, a large storm storage tank and a construction method thereof are proposed in Korean Patent Registration No. 10-0802994. In the background art, the first step of excavating, selecting and laying foundation rubble layer after excavation; A second step of installing a rail or H-shaped steel on the foundation concrete to maintain a precise position and level on the foundation rubble layer; A third step of continuously installing the left and right side walls and the center walls in the front and rear directions on the rail or the H-shaped steel, and assembling by tensioning and fixing using a PS steel bar; A fourth step of finishing the floor slab by finishing with site-cast concrete or PC member to close the bottom plate opening; A fifth step of assembling and installing the door-shaped left and right ceiling slabs continuously installed and the door-shaped center ceiling slabs for closing the upper space between the center walls; A sixth step of assembling and installing the front and rear finishing walls in order to close the front and rear openings and the like of the flat box-shaped block group installed in the above order; An elastic sealing material is installed on the inner surface of the joints of the assembled members, and on the outer wall of the storage tank, a seat sheet or a permeation sheet is installed according to the purpose of the storage tank, and then the backfill is filled with a fine sand layer, and a check hole and a ventilation hole are installed on the storage tank. step; After completing the inlet and outlet connection facilities, the storage tank is constructed by sequentially performing the eighth step of covering the upper part of the reservoir and installing the necessary facilities.

The background art has the advantage that the edges are integrally formed on the wall, so that no reinforcement or index structure is required, but when the floor slab is completed by finishing the cast-in-place concrete or PC member to close the bottom plate opening, the bottom plate opening and There will be a physical interface between floor slabs. Therefore, this junction interface becomes vulnerable to the exponential structure, and has a possibility of generating a physical crack surface.

Korean Laid-Open Patent Publication No. 10-2010-0130354 Korean Laid-Open Patent Publication No. 10-2012-0066802 Korea Patent Registration No. 10-0988806

It is an object of the present invention to provide a method of constructing a PC storage tank using a PC underground continuous wall having excellent index and reinforcement effects at an edge portion where a PC underground continuous wall and a floor slab meet.

The construction method of PC storage tank which concerns on appropriate embodiment of this invention,

Installing a guide wall on an upper portion of the underground continuous wall;

Maintaining a hollow wall by injecting a stabilizer into the excavation hole while trenching trenches between the guide walls facing each other using the excavating equipment;

After installing the PC panel in the excavation hole, install the grouting index plate between neighboring PC panels, perform joint grouting, and seal the outer wall with high-weight cement-bentonite to build underground continuous walls. ;

Excavating the ground of the inner region enclosed with the PC panel and supporting it with the support;

Casting the discarded concrete on the excavated bottom surface, and constructing the bottom slab by pouring the foundation concrete on the discarded concrete upper surface;

Erecting a plurality of PC pillars on an upper surface of the floor slab, and installing PC beams on the top of each PC pillar, while installing the PC beams supported by the PC panels on the recesses recessed in the upper surface of the PC panels;

After constructing the upper PC slab on the upper surface of the PC beam, characterized in that it comprises the step of pouring topping large concrete.

In addition, it characterized in that the construction further comprises the step of bonding the plate-shaped index plate installed in the lower portion of the PC panel when placing the concrete for the exponential construction.

In addition, an angle type index plate made of rubber material is positioned at the corner where the PC panel and the floor slab meet for index construction, and the angle type index plate is installed at the corner where the PC panel and the floor slab contact by the cover plate with the fixing force of the anchor bolt. It is characterized in that the construction is in close contact with the plate.

In addition, for reinforcing coupling of the corner portion where the PC panel and the floor slab meet, a steel wire embedded in the bottom slab is introduced into a sheath tube embedded at the bottom side of the PC panel, and then fixed on the PC panel side after curing of the foundation concrete. It is characterized in that the construction is further included.

In addition, when laying the foundation concrete, the index plate installed at the lower part of the PC panel is bonded, or the L-shaped inner plate, the rubber plate and the cover plate, which are bonded to the corner portion where the PC panel and the bottom slab meet, are sequentially stacked so that the PC panel and the floor are anchor bolts. Bonding to the slab; For reinforcing coupling of the corner part where the PC panel and the floor slab meet, the steel wire embedded in the bottom slab is introduced into the sheath pipe embedded at the bottom side of the PC panel, and then the curing is performed on the PC panel side after curing of the foundation concrete. It is characterized by being included.

In addition, after installing the earth anchors in the height direction in the PC panel, and the second PC panel vertically stacked at a predetermined interval on the front of the PC panel, and stepped to remove the earth anchor existing in the corresponding position after each step concrete It is characterized in that it further comprises the step of constructing the plywood by pouring.

In addition, vertically stack any one of the third PC panel, the steel sheet, and the plywood formwork at a predetermined interval on the front side of the PC panel supported by the strut, and then cast the site concrete and remove the strut, and again the third PC panel, steel sheet, After repeating any one of the plywood formwork stacked vertically, the step of placing the concrete concrete is characterized in that it further comprises the step of constructing the plywood wall.

According to the PC storage tank utilizing the PC underground continuous wall of the present invention and its construction method, the edge portion where the plate-shaped index plate is installed in the lower part of the PC panel constituting the underground continuous wall when the foundation concrete is placed, or the PC panel and the floor slab meet An index module composed of an inner plate, a rubber plate and a cover plate is installed at the bottom to have an index structure at the joining edge portion of the PC panel and the bottom slab.

In addition, the strands are tension-fixed at the corners of the PC panel and the floor slab to obtain a reinforcing structure.

In addition, the wall can be used as a permanent structure after using the wall as a temporary wall can reduce the cost of the facility.

In addition, the temporary wall and the structural wall can be constructed on the same line to reduce the air and cost of reducing the amount of earthwork.

Therefore, the present invention can be applied to the underground assembly PC storage tank, the initial stormwater treatment facility storage tank, parking lot, underground roadway, sewage pipes and the like.

The following drawings, which are attached in this specification, illustrate the preferred embodiments of the present invention, and together with the detailed description thereof, serve to further understand the technical spirit of the present invention. It should not be construed as limited.
1 is a state diagram of the construction of the underground assembled PC storage tank according to the present invention.
Figure 2a is an illustration of a PC panel applied to the present invention.
Figure 2b is a various cross-sectional state diagram of the PC panel applied to the present invention.
Figure 3 is a cross-sectional view of a corner panel applied to the present invention.
4 is a perspective view of a beam applied to the present invention.
Figure 5a is a perspective view of a column applied to the present invention.
Figure 5b is a perspective view of each of the various forms of the upper slab applied to the present invention.
6 is an exemplary view showing a state in which the guide wall is constructed on the ground.
7 is a state in which trench excavation is constructed between guide walls.
8 is an exemplary view showing a state of constructing a PC panel constituting the underground continuous wall in the excavation hole.
9 is an exemplary view showing a state in which cast concrete and foundation slab are constructed after excavating a portion surrounded by a PC panel.
10 is an exemplary view showing a state in which pillars and beams are constructed.
11 is a construction state diagram showing an installation state of the upper PC slab;
12A and 12B are exemplary views showing a state in which a PC panel and an upper PC slab are integrated by pouring topping large concrete;
Figure 12c is a view showing a part of the PC panel that the upper slab and the topping concrete is connected.
FIG. 12D illustrates a part of a PC panel to which beams, upper slabs, and topping concrete are connected. FIG.
FIG. 13 is an exemplary view showing a state of construction using a plate-shaped index plate at a joint portion between a PC panel and a bottom slab. FIG.
14A is an exemplary view showing a state of construction using an angled index plate in the junction between the PC panel and the bottom slab.
Fig. 14B is a sectional view of the main parts of Fig. 14A;
Figure 15a is a construction state reinforcement using a steel wire junction between the PC panel and the floor slab.
Fig. 15B is a sectional view of the main parts of Fig. 15A;
FIG. 16 is an exemplary view in which all of the plate-shaped index plate, the angle-type index plate, and the strand are installed to index and reinforce the corner portion of the storage tank. FIG.
17 is a view showing a process and a completed perspective view of the construction of the plywood wall.
18 is a view showing a process and a completed perspective view of the plywood construction when the wall is high.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings, but the present invention is not limited thereto.

First, the prefabricated PC storage tank of the present invention, as shown in Figures 1, 3 and 11, the PC panel 20 and the corner panel 21 constituting the wall (temporary wall) and the discarded concrete 30 forming the bottom layer of the storage tank ) And a bottom slab 32, a beam 36 constituting the upper structure of the storage tank, the upper PC slab 38 and the topping concrete 39, and a pillar 34 for supporting the upper structure.

The PC panel 20 is made of precast concrete in a factory in the form of a cube having a width, a height, and a thickness as shown in FIG. 2A. At this time, PS steel wire, PS steel wire, steel rods, etc. are installed to reinforce the strength, and the cross section is solid as shown in FIG. Can be.

The corner panel 21 is disposed at the edge of the wall of the storage tank 1 and may have various cross-sectional shapes as shown in FIG. 3. That is, the corner panel 21 may have an L-shaped cross section as shown in FIGS. 3 (a) and 3 (b) or a straight cross section as shown in FIG. 3 (c) and (d). The corner panel 21 is made of the same precast concrete as the PC panel 20. In this case, grooves may be formed on both sides of the corner panel 21 in the vertical direction to install the water repellent material. At this time, the direction between both grooves forms a right angle.

The discarded concrete 30 is poured into the site concrete as a part forming the bottom floor of the storage tank. The discarded concrete 30 is made after earthwork is carried out inside the wall. The bottom slab 32 is installed on the upper surface of the discarded concrete 30. The bottom slab 32 is reinforced with reinforcement, the reinforced reinforcement is composited with the site-cast concrete.

The beam 36 is made of precast concrete as shown in FIG. 4 and has a rectangular cross section in the longitudinal direction. At this time, it has a synthetic reinforcing bar projecting to the upper surface and both ends of the beam (36). The beam 36 shown in this embodiment is one form, and the present invention is not limited to the illustrated form.

The pillar 34 has a rectangular cross section in the height direction as shown in FIG. 5A and has haunches at the top and the bottom. In addition, the pillar 34 is a synthetic reinforcing bar is installed on the top for the synthesis with the slab.

The upper PC slab 38 is well known in the art to which the present invention belongs, such as a half slab, a hollow slab of (B), a double tee slab of (C), and an inverted rib slab of (D) as shown in FIG. Any PC slab can be used.

The construction method of the underground assembly storage tank made in this way is demonstrated.

First, as shown in FIG. 6, the guide wall 12 is installed in an upper portion of the ground 11 on which the underground continuous wall is to be constructed. In this case, the guide wall 12 may be installed by installing the formwork at the position where the PC panel 20 is to be drawn, and then installing concrete to the outside of the formwork or installing the H-shaped steel. The guide wall 12 serves as a guideline when excavating the ground and provides the role of the cradle of the PC panel and the safety of the topsoil.

Next, trench excavation is performed using the excavation equipment vertically between the guide walls 12 and 12 facing each other as shown in FIG. 7, and a stabilizer is introduced into the excavation hole to prevent the collapse of the hollow walls. The stabilizer can be, for example, cement-betonite. Trench excavation takes place along the guide walls 12, 12. When excavation is made along the guide walls 12 and 12, an excavation hole 13 is formed. At this time, install the inclinometer or sonic measuring equipment in the excavation equipment to adjust the verticality and secure the depth of excavation. During excavation, a side guard plate for protecting the PC panel and a panel guide for panel contact may be installed.

Next, the PC panel 20 is installed to be connected to the excavation hole 13 as shown in FIG. 8. The PC panel 20 may be solid as shown in FIG. 2B (A), or may be hollow having a hollow hole 20a as shown in (B). In this case, as shown in FIG. 8, a grouting index plate 22 is installed between neighboring PC panels 20 and 20, and joint grouting is performed to seal the outer wall portion with a high specific weight of cement-bentonite. The grouting index plate 22 is provided with a packer and a grouting hose therein, and the grout material injected through the grouting hose is discharged through the holes 22a of the grouting index plate 22 to form a grouting lining film. As a result, continuous walls, that is, underground continuous walls, are constructed in the ground. This underground continuous wall becomes an earth wall during the excavation work and forms a wall of the storage tank after the excavation is completed. Therefore, according to the present invention, it is not necessary to separately build the temporary barrier wall, and since the temporary barrier wall constitutes the wall of the storage tank, there is no need to separately construct the wall of the storage tank after the excavation is completed.

Here, the edge portion of the wall may be any one of the corner panels 21 having various cross-sectional shapes as shown in FIG. 3.

At this time, it is preferable that the cement bentonide 19 is filled between the PC panel 20 and the excavation hole 13 as shown in FIG. 9.

Next, as shown in FIG. 9, the ground of the inner region surrounded by the PC panels 20 is excavated and supported by the support holes 25. Here, the support ball 25 refers to a brace and its accessories installed to prevent the ground continuous wall made of the PC panel 20 during excavation. At this time, the installation of the vertical beam is repeated according to the excavation depth.

Then, cast concrete 30 on the bottom surface of the excavated excavation hole as shown in Figure 10, and the foundation concrete is poured on the discarded concrete upper surface to construct a floor slab 32 of a predetermined thickness. Reinforcing bars may be arranged in the bottom slab 32. At this time, the bottom slab 32 is preferably to form a haunch along the corner.

Then, the PC pillar 34 is erected at each position set on the upper surface of the floor slab 32 as shown in FIG. 11, and the PC beam 36 is installed on the top of the PC pillar 34. Since the joint between the PC pillar 34 and the bottom slab 32 and the PC pillar 34 and the PC beam 36 are well known in the art, detailed description thereof will be omitted. At this time, it is preferable to install the PC beam 36 supported by the PC panel 20 while being located in the grooved jaw 20b formed by recessing the upper surface of the PC panel 20 as shown in FIGS. 12A to 12D. Therefore, the PC beam 36 has a firm and stable installation structure.

Next, after the upper PC slab 38 is constructed on the upper surface of the PC beam 36, the topping concrete 39 is poured as shown in FIGS. 12A and 12B. At this time, it can be constructed by embedding the deformed reinforcing bar 27 exposed to the upper portion of the PC panel 20 in the thickness layer of the topping concrete 39 to be embedded. FIG. 12A illustrates a state in which the topping concrete 39 is poured while the upper PC slab 38 is supported on the upper end of the PC panel 20. FIG. 12B shows that the end of the PC beam 36 has a PC panel ( The deformed reinforcing bar 27 is inserted into the topping concrete 39 by inserting the end portion of the PC beam 36 in a state of being supported by the grooved jaw 20b formed by being recessed on the upper surface of 20). In this case, the topping concrete 39 layer is synthesized in the PC panel 20 through the deformed reinforcing bar 27, so that the upper PC slab 38 is stable between the topping concrete 39 and the PC beam 36. It is installed.

Here, the step of bonding the plate-shaped index plate 31 installed in the lower portion of the PC panel 20 as shown in Figure 13 when the foundation concrete for the exponential construction may be further included. At this time, the plate-shaped index plate 31, as shown in Figure 13 so that the other part is embedded in the bottom panel 32 in the PC panel 20. Therefore, it has a watertight structure by the plate-shaped index plate 31 at the corner portion where the PC panel 20 and the bottom slab 32 are in contact with each other. At this time, the plate-shaped index plate 31 may be made of a plate-like metal, synthetic resin, composite material.

As another method, an angle type index plate 42 made of rubber may be installed at an edge portion where the PC panel 20 and the bottom slab 32 meet as shown in FIGS. 14A and 14B. At this time, the angle type index plate 42 is installed by the cover plate 44 after being in close contact with the inner plate 40, 40 is installed in the corner that the PC panel 20 and the bottom slab 32 contact. Protrusions 44a are formed on the large surfaces of the inner plates 40 and 40 and the cover plate 44 to press the angled index plates 42, respectively. At this time, the cover plate 44 is L-shaped in close contact with the angle-shaped index plate 42 by the anchor bolt 46 fixed to the PC panel 20 and the bottom slab 32. The inner plate 40 and the cover plate 44 may be made of steel.

On the other hand, for the reinforcement coupling of the corner portion where the PC panel 20 and the bottom slab 32, in the sheath tube 24 embedded in the lower side of the PC panel 20, as shown in Figure 15a and 15b After the steel wire 33 embedded in the bottom slab 32 is drawn in, the curing of the foundation concrete may be further included and the step of fixing the PC panel 20 side. At this time, the sheath tube 24 is located in the joining groove 201 connected to the bottom slab 32 in the state embedded in the PC panel 20, the upper end of the fixing groove 202 of the PC panel 20 Is located in.

As such, when the steel wire 33 is tensioned and installed at the corner portion where the PC panel 20 and the bottom slab 32 meet, the steel wire 33 generates a compressive force at an end portion of the bottom slab 32, thereby making reinforcement.

On the other hand, the present invention can be implemented by applying both the exponential method and the reinforcement method illustrated above as shown in FIG. Therefore, the exponential force at the bottom edge of the reservoir is doubled and the reinforcement is increased.

On the other hand, the present invention, after installing the earth anchors 61, 62 in the height direction in the PC panel 20 as shown in Figure 17, the second PC panel 71 at a predetermined interval on the front surface of the PC panel 20. ) 72 and 73 are stacked vertically and then the earth anchors 61 and 62 existing at the corresponding positions are sequentially removed while the concrete concrete 81 is poured in each removal step to construct the plywood wall. Can be.

That is, after installing the second PC panel 71 in the first step, the site concrete is poured and the first earth anchor 61 is removed. Next, after installing the second PC panel 72 in the second step, the site concrete is poured and the second earth anchor 62 is removed. Then, after installing the second PC panel 72 in the third step is a method made by pouring the site concrete.

In addition, when the height is high by another method of plywood construction, the third PC panel 73 is vertically laminated at a predetermined interval on the front surface of the PC panel 72 supported by the strut 88 as shown in FIG. After placing the concrete 81 and removing the struts, the third PC panel 73 is vertically stacked, and then the step of pouring the field concrete 81 may be repeated to construct the plywood wall. In this case, a steel plate or plywood formwork may be used in place of the third PC panel 73.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the above teachings. will be. The invention is not limited by these variations and modifications, but is limited only by the claims appended hereto.

12: guide wall
13: excavator
20: PC panel
24: Sheath tube
27: deformed rebar
30: cast concrete
31: plate-shaped index plate
32: floor slab
33: liner
38: Upper PC Slab
39: topping concrete
42: angled index plate

Claims (8)

delete Installing a guide wall on an upper portion of the underground continuous wall;
Maintaining a hollow wall by injecting a stabilizer into the excavation hole while trenching trenches between the guide walls facing each other using the excavating equipment;
After installing the PC panel in the excavation hole, install the grouting index plate between neighboring PC panels, perform joint grouting, and seal the outer wall with high-weight cement-bentonite to build underground continuous walls. ;
Excavating the ground of the inner region enclosed with the PC panel and supporting it with the support;
Casting the discarded concrete on the excavated bottom surface, and constructing the bottom slab by pouring the foundation concrete on the discarded concrete upper surface;
Erecting a plurality of PC pillars on an upper surface of the floor slab, and installing PC beams on the top of each PC pillar, while installing the PC beams supported by the PC panels on the recesses recessed in the upper surface of the PC panels;
Constructing an upper PC slab on the upper surface of the PC beam, and then pouring the topping large concrete,
Underground concrete for construction of exponential construction, the plate-like exponential plate installed in the lower part of the PC panel is further included, the step of using the underground continuous wall, characterized in that the construction is possible to install in the strut structure or earth anchor structure Construction method of storage tank. Installing a guide wall on an upper portion of the underground continuous wall;
Maintaining a hollow wall by injecting a stabilizer into the excavation hole while trenching trenches between the guide walls facing each other using the excavating equipment;
After installing the PC panel in the excavation hole, install the grouting index plate between neighboring PC panels, perform joint grouting, and seal the outer wall with high-weight cement-bentonite to build underground continuous walls. ;
Excavating the ground of the inner region enclosed with the PC panel and supporting it with the support;
Casting the discarded concrete on the excavated bottom surface, and constructing the bottom slab by pouring the foundation concrete on the discarded concrete upper surface;
Erecting a plurality of PC pillars on an upper surface of the floor slab, and installing PC beams on the top of each PC pillar, while installing the PC beams supported by the PC panels on the recesses recessed in the upper surface of the PC panels;
Constructing an upper PC slab on the upper surface of the PC beam, and then pouring the topping large concrete,
An angled index plate made of rubber is placed at the corner where the PC panel and the bottom slab meet for index construction, and the angle type index plate is mounted on the inner plate installed at the corner where the PC panel and the bottom slab are contacted by the cover plate with the fixing force of the anchor bolt. Construction method of underground assembly type PC storage tank which can be constructed in strut structure or earth anchor structure by using PC underground continuous wall characterized in that it is constructed in close contact. The method of claim 3,
For reinforcing coupling of the corner part where the PC panel and the floor slab meet, the steel wire embedded in the bottom slab is introduced into the sheath pipe embedded at the bottom side of the PC panel, and then the curing is performed on the PC panel side after curing of the foundation concrete. Construction method of underground assembly type PC storage tank that can be constructed in strut structure or earth anchor structure by using PC underground continuous wall, characterized in that the construction is included. delete The method according to claim 2 or 3,
After installing the earth anchors in the PC panel in the height direction, lay the second PC panels vertically with a certain distance on the front of the PC panel, and remove the earth anchors in the corresponding position, and then install the site concrete at every step. Construction method of underground assembly type PC storage tank can be constructed in a strut structure or earth anchor structure using the PC underground continuous wall, characterized in that further comprising the step of constructing the plywood wall. The method according to claim 2 or 3,
Lay out vertically one of the third PC panel, steel plate, and plywood formwork at regular intervals on the front side of the PC panel supported by strut. Lay out any one of the vertically stacked and then cast concrete on the site by repeating the step of constructing the plywood using the underground continuous wall PC underground construction available in the strut structure or earth anchor structure Construction method of storage tank. An underground assembly type PC storage tank that can be constructed in a strut structure or an earth structure using a PC underground continuous wall, which is manufactured by the method of claim 2.

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