JP2023001683A - Construction method of underground structure and underground structure as well as precast concrete side wall or intermediate wall/column therefor - Google Patents

Abstract

To provide a construction method of an underground structure allowing cost to be reduced and usability to be expanded by making a precast concrete side wall thinner and preventing damage of the precast concrete side wall even upon large overburden.SOLUTION: A construction method comprises steps of: at construction sites on both side wall parts, installing a precast concrete side wall 2 to be a body structure in the ground, in which steel material 5 is placed as core material in place of main reinforcement as well as soil retention steel material 5B is formed for resistance in a lateral direction against soil-water pressure and the like by extending the steel material 5 upward from an upper end surface; constructing a top cap 3 to be a body part between the precast concrete side walls 2, 2 after excavating and removing the ground down to a position where the top cap between the precast concrete side walls 2, 2; and finishing a shallower part of the top cap through refilling therein in advance.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method for constructing underground structures such as semi-underground tunnels, underground parking lots, bicycle parking lots, utility tunnels, subways, and underpasses.

The applicant proposed a method for constructing an underground structure with a large overburden, etc., in Patent Document 1 below. Specifically, a method for constructing an underground structure having at least both side walls, a top slab and a bottom slab, wherein metal inserts or steel materials are inserted into the construction sites of the side walls over a predetermined depth from the upper end face. The precast concrete side wall that forms the main structure is formed with a buried part, and multiple temporary steel members are detachably provided so as to protrude upward for lateral resistance such as soil and water pressure. After excavating and removing the ground up to the position where the top slab between these precast concrete side walls is built, between the precast concrete side walls, on the lower side avoiding the embedded part of the insert metal fitting or steel material A first step in which concrete is placed and combined with and integrated with the precast concrete side wall to complete the top plate portion that will be the main body structure in advance; a second step of excavating the ground deeper than the top slab and finally excavating to the construction depth of the bottom slab; and a third step of constructing a bottom slab that forms a main structure by connecting and integrating with the precast concrete side wall.

According to this underground structure construction method, in underground structures with large earth coverings, it is possible to absorb the installation error of the side wall, minimize the scale and period of ground occupation associated with construction, and affect the surrounding environment. Effects such as minimization, transportation and on-site work can be facilitated, and structural strength can be secured.

JP 2011-122386 A

When constructing an underground structure deep underground, it is necessary to increase the thickness of the precast concrete side wall because the precast concrete side wall receives a large amount of soil and water pressure. There was a concern that the cost would increase and the applicability of this construction method would decrease.

Further, in the underground structure construction method described in Patent Document 1, temporary steel members are provided on the upper end surface of the precast concrete side wall so as to protrude upward. As shown in 20, the insert metal fitting 52 embedded over a predetermined depth from the upper end surface of the precast concrete side wall 50 is bolted through the base plate 53 provided at the end of the temporary steel member 51. As shown in FIG. 21, for a steel material 55 embedded to a predetermined depth from the upper end surface of a precast concrete side wall 50 and provided with a bearing plate 54 and a stud (not shown) at the tip of the embedded side The temporary steel material 51 is spliced through a splicing plate 56 to be detachable.

However, when the temporary steel material protruding upward is provided on the upper end surface of the precast concrete side wall by such a method, when the earth covering becomes large, excessive stress is concentrated on the fixed part of the temporary steel material to the precast concrete side wall, There was a risk that the precast concrete sidewalls would crack and break.

Therefore, the main object of the present invention is to reduce the thickness of the precast concrete side walls to reduce costs and expand applicability, and to prevent damage to the precast concrete side walls even when overburden is large.

In order to solve the above problems, the present invention according to claim 1 is a method for constructing an underground structure having at least both side wall portions, a top slab portion and a bottom slab portion,
A steel material is arranged as a core material in place of the main reinforcement in the construction part of the both side walls, and the steel material extends upward from the upper end surface and is a steel material for earth retaining wall for lateral resistance such as earth water pressure. The precast concrete side walls forming the main body structure are erected in the ground, and the ground between the precast concrete side walls is excavated to the position where the top slab is to be constructed. After that, the main body structure is formed between the precast concrete side walls. A first step of constructing the top plate and backfilling to complete the shallower part than the top plate in advance;
a second step of excavating the ground deeper than the top slab surrounded by the precast concrete side wall and the top slab, and finally excavating to the construction depth of the bottom slab;
and a third step of placing concrete in a bottom slab construction site and connecting and integrating with the precast concrete side walls to construct the bottom slab that will be the main body structure. A construction method is provided.

In the invention according to claim 1, since the precast concrete side wall is structured such that the steel material is arranged as the core material instead of the main reinforcement, the cross-sectional area of the steel material is reduced compared to the conventional reinforced concrete structure using deformed bar steel as the main reinforcement. As a result, the bending resistance of the precast concrete as a whole increases, and as a result, it becomes possible to reduce the thickness and weight of the precast concrete members. Applicability can be expanded.

In addition, since the steel material used as the core material of the precast concrete member extends upward from the upper end surface and forms the steel material part for the retaining wall that can be used as the retaining wall during construction, the earth covering is large, and the above-mentioned Even if a large amount of earth and water pressure is applied from the side to the steel material for the earth retaining wall, the continuous resistance in the depth direction can be secured by the steel material extending continuously from the core material, and damage such as cracks in the precast concrete member can be prevented. can be prevented.

As the present invention according to claim 2, a method for constructing an underground structure having both side walls, an intermediate wall or intermediate pillar between both side walls, a top slab and a bottom slab,
In each span partitioned by the side walls, the intermediate wall between the side walls, or the intermediate column, a steel material is arranged as a core material instead of the main reinforcement in the construction part of the side wall, and the steel material is above the upper end surface. The precast concrete side wall that forms the main structure, which extends to the side and forms the steel part for the earth retaining wall for lateral resistance such as soil water pressure, is erected in the ground, and the intermediate wall or intermediate pillar construction part , a main body structure in which a steel material is arranged as a core material instead of the main reinforcement, and the steel material extends upward from the upper end surface to form a steel material part for an earth retaining wall for lateral resistance such as earth and water pressure; A precast concrete intermediate wall or intermediate pillar is erected in the ground, and after excavating and removing the ground up to the position where the top slab is constructed between these spans, the top slab that will be the main structure is constructed between the precast concrete side walls. , a first step of preliminarily completing the shallow portion below the top plate portion by backfilling;
a second step of excavating the ground deeper than the top slab surrounded by the precast concrete side walls and the top slab, and finally excavating to the construction depth of the bottom slab;
and a third step of placing concrete in the bottom slab construction site and connecting and integrating the precast concrete side wall and the precast concrete intermediate wall or intermediate pillar to construct the bottom slab that will be the main body structure. A method of constructing an underground structure is provided, characterized by:

The invention according to claim 2 is a construction method for an underground structure having intermediate walls or intermediate columns between side walls. If there is an intermediate wall or an intermediate column between the side walls, it is possible to construct the top slab after excavating all the ground for constructing the top slab between the side walls, but in this case, the excavation scale becomes large. , the ground occupancy period will be prolonged. Therefore, each span partitioned by both side walls, an intermediate wall between both sides or an intermediate pillar is sequentially erected with precast concrete members, excavated the ground to the construction position of the top slab, constructed the top slab, and backfilled the top slab. By constructing in the procedure of preceding completion of the shallow part and the shallow part, the ground occupation period can be shortened.

As the present invention according to claim 3, there is provided a method for constructing an underground structure according to any one of claims 1 and 2, wherein the steel material serving as the core material of the precast concrete side wall is arranged instead of the main reinforcement on the side of the ground. be done.

In the invention according to claim 3, by using the steel material as a core material in place of the ground-side main reinforcement having a high tensile stress, the bending resistance of the precast concrete side wall is increased, and the thickness and weight of the precast member are further reduced. certainly possible.

As the present invention according to claim 4, T-shaped steel is used as the steel material, and the T-shaped steel is arranged so that the flange portion faces the outer surface side of the precast concrete side wall and the web portion protrudes inward. A method for constructing an underground structure according to any one of claims 1 to 3 is provided.

In the invention according to claim 4, a T-shaped steel is used as the steel material, and the T-shaped steel is arranged so that the flange portion faces the outer surface side of the precast concrete side wall and the web portion protrudes inward. Therefore, the center of gravity of the steel material is closer to the outer surface side of the precast concrete side wall than when H-shaped steel is used. In addition, since the bending strength is greater than that of conventional reinforced concrete structures using deformed steel bars, support by struts during internal excavation can be simplified. Furthermore, in the production of precast concrete side walls, many mechanical joints are installed as joints with the bottom and top slabs constructed with cast-in-place concrete. Compared to the case, it is possible to arrange the mechanical joints at a predetermined pitch without interference between the steel materials and the mechanical joints, and the filling property of the concrete is improved.

As the present invention according to claim 5, the precast concrete side wall and/or the precast concrete intermediate wall or intermediate column protrude downward from the lower end surface for lateral resistance such as vertical bearing capacity and earth and water pressure. There is provided a method for constructing an underground structure according to any one of claims 1 to 4, comprising a plurality of steel piles.

In the invention according to claim 5, the precast concrete side wall and/or the precast concrete intermediate wall or intermediate column protrudes downward from the lower end surface for lateral resistance such as vertical bearing capacity and earth and water pressure. A plurality of steel piles are provided so as to do so. It is also possible to use precast concrete members for the entire embedded length, but in this case not only is the depth of excavation of the installation groove deeper, but the cost of precast members increases, the construction period is prolonged, and the construction labor and construction costs are increased. cause an increase. Therefore, by providing a plurality of steel piles at the lower end, it is possible to make the ditch shallow and secure sufficient vertical bearing capacity and lateral resistance to earth and water pressure by these steel piles.

As the present invention according to claim 6, the precast concrete side wall and/or the precast concrete intermediate wall or intermediate column has a film pasted or a release agent applied to at least the inner wall surface side. A method of constructing an underground structure according to any of the preceding is provided.

In the invention according to claim 6, a film is pasted or a release agent is applied to at least the inner wall surface side of the precast concrete side wall and/or the precast concrete intermediate wall or intermediate column. . Since muddy water and soil cement adhere to the surface of the precast concrete member during construction, the surface of the precast concrete member becomes dirty. The inner wall surface side can be finished easily and beautifully.

As a seventh aspect of the present invention, a steel material is arranged as a core material instead of the main reinforcement, and the steel material extends upward from the upper end surface to provide lateral resistance such as earth and water pressure. A precast concrete side wall with multiple steel piles protruding downward from the lower end face to form a part and for lateral resistance such as vertical bearing capacity and earth and water pressure, and the upper part between the precast concrete side walls and a bottom slab provided below between precast concrete side walls and constructed of cast-in-place concrete.

According to an eighth aspect of the present invention, one or a plurality of precast concrete intermediate walls or intermediate columns are provided between the precast concrete side walls, and the precast concrete intermediate walls or intermediate columns include steel as a core material instead of the main reinforcement. The steel material extends upward from the upper end surface to form a steel material part for retaining walls for lateral resistance such as earth and water pressure, and also for vertical bearing capacity and lateral resistance such as earth and water pressure. 8. An underground structure according to claim 7, wherein a plurality of steel piles are provided so as to protrude downward from the lower end face for the purpose of the underground structure.

As a ninth aspect of the present invention, a steel material is arranged as a core material instead of the main reinforcement, and the steel material is arranged so as to extend upward from the upper end surface of the earth retaining wall for lateral resistance such as earth and water pressure. A precast concrete side wall or a precast concrete intermediate wall/column is provided, which is characterized in that it forms a steel part and is provided with a plurality of steel piles so as to protrude downward from the lower end face.

As described in detail above, according to the present invention, by reducing the thickness of the precast concrete side wall, it is possible to reduce costs and expand applicability, and prevent damage to the precast concrete side wall even when the overburden is large.

It is a longitudinal section showing underground structure 1A concerning the present invention. It is a construction procedure (part 1) of the underground structure 1A. 1(A) is a vertical cross-sectional view of a side surface, and (B) is a vertical cross-sectional view of a front side, showing a precast concrete side wall 2. FIG. FIG. 10 shows a precast concrete side wall 2 according to a modification, in which (A) is a side longitudinal sectional view and (B) is a front longitudinal sectional view. 5 is a view taken along line VV of FIGS. 3 and 4; FIG. It is a bending moment diagram of a box culvert. It is a cross-sectional view of the precast concrete side wall 2 at the bottom slab joint. Fig. 2 is a cross-sectional view of a main part showing an example of a water stop structure between precast concrete side walls 2, 2; It is the construction procedure (part 2) of the underground structure 1A. It is the construction procedure (part 3) of the underground structure 1A. It is the construction procedure (part 4) of the underground structure 1A. FIG. 3 is a cross-sectional view of a main part showing a joint portion between a precast concrete side wall 2 and a precast concrete top slab 3; FIG. 3 is a cross-sectional view of a main part showing a joint structure between a precast concrete side wall 2 and a top plate 3; It is a construction procedure (No. 5) of the underground structure 1A. This is the construction procedure (No. 6) of the underground structure 1A. It is a construction procedure (part 7) of the underground structure 1A. It is the construction procedure (No. 8) of the underground structure 1A. 4 is a vertical cross-sectional view of a main portion showing a joint portion with the bottom plate portion 4; FIG. FIG. 11 is a vertical cross-sectional view showing an underground structure 1B according to a second embodiment; FIG. 10 (A) is a vertical cross-sectional view of the side surface, and (B) is a vertical cross-sectional view of the front surface, showing a conventional fixing structure for a temporary steel member 51. FIG. FIG. 10 (A) is a vertical cross-sectional view of a lateral side, and (B) is a vertical cross-sectional view of a front side, showing a fixing structure of a conventional temporary steel material 51 according to a modified example.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Example 1]
1 to 3, an underground structure 1A has steel members 5, 5, . A plurality of steel piles 6 , 6 . A precast concrete side wall 2 provided, a top slab 3 provided at the upper part between the precast concrete side walls 2, 2, and a lower part between the precast concrete side walls 2, 2, and constructed with cast-in-place concrete and a bottom plate portion 4.

Hereinafter, the underground structure 1A will be specifically described in detail according to the order of construction.

(First step)
The first step is to construct the top slab 3 that will be the main structure between the precast concrete side walls 2, 2, and backfill the top slab to complete the shallower portion in advance. This first step will be described in detail with reference to FIGS. 2 to 14. FIG.

First, as shown in FIG. 2, a heavy excavator is used to excavate the side wall construction site for erecting the precast concrete side wall 2, and then the precast concrete side wall 2 is erected.

As shown in FIGS. 3 to 5, the precast concrete side walls 2 are arranged with steel materials 5, 5, . . . Until the construction of the top slab 3, it functions as a steel material part 5B for retaining walls for lateral resistance such as earth and water pressure, and for lateral resistance such as vertical bearing capacity and earth and water pressure A pile provided with a plurality of steel piles 6, 6... is used so as to protrude downward from the end face.

The steel member 5 has a core steel member 5A embedded in the precast concrete side wall 2 and a retaining wall steel member 5B extending upward from the upper end surface of the precast concrete side wall 2, which are continuously formed. It is.

As shown in FIG. 5, the steel members 5 are preferably arranged in place of the main reinforcements arranged on the ground side of the precast concrete side wall 2 and on the inside of the structure, respectively. It is better to arrange reinforcing bars using steel bars.

By arranging the steel material 5 as a core material instead of the ground-side main reinforcement, in a box culvert structure such as the underground structure 1A according to the present invention, as shown in FIG. Compared to a reinforced concrete structure using a deformed steel bar, the amount of cross-sectional area of the steel material is increased, and the bending strength is increased for the same cross-sectional area. As a result, the thickness and weight of the precast concrete side wall 2 can be reduced, and it is possible to cope with underground structures of great depth, and the applicability of this construction method can be expanded.

In addition, by extending the steel material 5 from the upper end surface of the precast concrete side wall 2 to a length reaching the ground above, and installing a plate material such as a steel sheet pile on the ground side, it can be used as an earth retaining wall. I have to. In order to extend the steel material 5 upward from the upper end surface of the precast concrete side wall 2, as shown in FIG. Alternatively, as shown in FIG. 4 , a splice plate 7 may be used to splice and join the ends of the cut steel materials at a position protruding upward from the upper end surface of the precast concrete side wall 2 .

In this way, the steel member 5 used as the core material of the precast concrete side wall 2 extends upward from the upper end surface of the precast concrete side wall 2 to form the retaining wall steel member 5B that can be used as a retaining wall during construction. Therefore, even if the earth overburden is large and a large earth and water pressure is applied to the retaining wall steel material portion 5B from the side, the steel material 5 continuously extending from the core material provides a continuous resistance force in the depth direction. can be secured, and damage such as cracking of the precast concrete side wall 2 can be prevented.

As the steel material 5, known shaped steel materials such as T-shaped steel, H-shaped steel, I-shaped steel, and channel steel can be used, but it is particularly desirable to use T-shaped steel. As shown in FIG. 5, the T-shaped steel is arranged so that the flange portion 5f faces the outer surface side (ground side) of the precast concrete side wall 2 and the web portion 5w protrudes inward. is good.

By arranging the steel material 5 made of the T-shaped steel in the above-described orientation, the center of gravity position of the steel material is lower than when the H-shaped steel is arranged so that the flange portion faces the outer surface side of the precast concrete side wall 2. is closer to the outer surface side of the precast concrete side wall 2, so in the case of the same cross-sectional area, using T-shaped steel increases the effective height and is advantageous in terms of design.

In addition, since the bending strength is greater than that of conventional reinforced concrete structures using deformed steel bars, support by struts during internal excavation can be simplified.

Furthermore, in the production of the precast concrete side wall 2, as shown in FIG. 8, 8 . . . are installed. At that time, as shown in FIG. As shown in FIG. When used, the steel members 5 and the mechanical joints 8 do not interfere with each other, and can be arranged at positions corresponding to the main reinforcing bars at substantially equal intervals, thereby improving the filling properties of concrete.

It is desirable that the precast concrete side wall 2 is pasted with a film or coated with a release agent at least on the inner wall surface side.

The precast concrete side wall 2 and the steel pile 6 are, as shown in FIG. It is fixed by bolts through the base plate 6a provided in the steel material, or, although not shown, is embedded from the lower end surface of the precast concrete side wall 2 to a predetermined depth and a steel material provided with a bearing plate or stud at the tip of the embedded side By splicing the steel pile 6 via a splicing plate, it is detachably provided.

When erecting, a predetermined water stop structure is provided at the joint surfaces of the precast concrete side walls 2,2. As this water stop structure, a known structure can be used without limitation, but it is particularly desirable to use the suitable water stop structure disclosed in JP-A-2011-122386. As shown in FIG. 8, the water stop structure of the precast concrete side walls 2 disclosed in the same publication is embedded in the side surface of one of the precast concrete side walls 2A, 2A on the opposite sides of the adjacent precast concrete side walls 2A, 2B. A space 11 closed from the surroundings is formed by the engagement between the one side joint fitting 10A and the other side joint fitting 10B embedded in the side surface of the other precast concrete side wall 2B. 2A and 2B are formed with concave grooves 12 facing each other along the longitudinal direction of the member, and a water stop plate 13 is inserted and installed across the concave grooves 12 and 12, and a grout material is inserted into the coffer space 11. 14 is filled.

After the above steps are completed, as shown in FIG. Excavate to remove. When excavating the ground, as shown in FIG. 10, struts 20 are erected between the retaining wall steel members 5B, 5B as required. The excavation depth is such that the top of the precast concrete side wall 2 is exposed and the top slab 3 in the next step can be constructed.

Once the excavation is finished, a top slab 3 is constructed between the precast concrete side walls 2, 2, as shown in FIG. For the construction of the top slab 3, a precast method of erecting a precast concrete top slab or a site-casting method using site-casting concrete can be adopted.

When constructing the top slab 3 by the precast method, the joint with the precast concrete side wall 2 is formed by embedding an anchor rod 21 in the upper part of the precast concrete side wall 2, as shown in FIG. In addition, a threaded coupler 22 is provided on the upper part thereof, and after the precast concrete top plate 3 is installed, a rod 24 is inserted through a sleeve 23 previously embedded in the corresponding position of the threaded coupler 22 and screwed. After connecting to the type coupler 22, a rod connection method that fastens the upper part, and as shown in FIG. It is desirable to employ a sleeve method or the like in which mortar is injected into the sleeve 25 for joining after inserting the reinforcing bars 26 protruding from the upper surface of the precast concrete side wall 2 . The inner diameter of the sleeve 25 is manufactured to be slightly larger than the outer shape of the reinforcing bar 26, so that the construction error of the top plate portion 3 can be absorbed by this portion.

Further, in the method of constructing the top slab 3 by the above-mentioned on-site casting method, for example, as shown in FIG. 13, main reinforcing bars 27, 27 . Then, a mechanical joint 28 is provided at the tip of the top slab 3, and a mechanical joint 30 attached to the tip of the top slab main reinforcing bar 29 is joined to the mechanical joint 28 to arrange the reinforcement of the top slab 3. After that, formwork is placed and concrete is poured.

Here, by arranging the top slab 3 on the upper surface of the precast concrete side wall 2 and embedding the retaining wall steel member 5B protruding upward from the upper end surface of the precast concrete side wall 2 in the top slab 3, Preferably, the bond between the precast concrete side wall 2 and the top slab 3 is strengthened. For example, when installing the precast concrete top slab 3 as shown in FIG. After installing the precast concrete top plate 3 while fitting the retaining wall steel member 5B into the fitting portion 31, the gap between the retaining wall steel member 5B in the fitting portion 31 and the retaining wall steel member 5B is filled with mortar.

After the top slab 3 is installed, as shown in FIG. 14, the retaining wall steel part 5B protruding above the top slab 3 is removed by gas cutting or the like, and then backfilled. and release the ground occupation.

(Second step)
After completing the shallower portion of the top slab 3 in advance in the first step, the top slab surrounded by the precast concrete side walls 2, 2 and the top slab 3 as shown in FIG. The ground is excavated to a depth of 3 or more, and finally excavated to the construction depth of the bottom plate portion 4. As shown in FIG. 16, the excavation is supported by struts 32, 32 as necessary, and the excavated earth and sand is discharged, for example, by opening a part of the top slab 3 and using a bucket (crane) on the ground. up to and carried out by a dump truck, etc.

(Third step)
After excavation to a predetermined depth (construction depth of the bottom slab 4) is completed, as shown in FIG. to be combined and integrated. The connection between the bottom slab 4 and the precast concrete side wall 2 is achieved by, for example, as shown in FIG. A mechanical joint 34 is provided, and a mechanical joint 36 attached to the tip of the main reinforcing bar 35 of the bottom slab is joined to the mechanical joint 34. After the reinforcement of the bottom slab 4 is arranged, the formwork is placed. and pour concrete.

After that, as a final finish, if a film is pasted on the inner wall surface side of the precast concrete side wall 2 in advance, it is peeled off to expose a clean concrete surface. In addition, when a release agent is applied, jet water is sprayed or a brush is cleaned to remove dirt such as muddy water and soil cement.

[Second form example]
In the above embodiment, the top slab 3 and the bottom slab 4 are bridged between the side walls 2, 2. However, as shown in FIG. An underground structure 1B partitioned by pillars 15 is also possible. The construction procedure is basically the same as the first embodiment described above, but when there is no construction yard, steel materials are arranged as core materials instead of at least part of the main reinforcement, and the steel materials are used in the soil. After using the intermediate wall 15 arranged to extend upward from the upper end surface for lateral resistance such as water pressure, the left span portion between the left side wall 2 and the intermediate wall 15 is formed in the first step. Construction of the top slab 3 is performed first, and only the retaining wall steel material 5B of the left side wall 2 is removed and backfilled, and then the right span portion between the intermediate wall 15 and the right side wall 2 and construction of the top slab 3, removal of the intermediate wall 15 and the steel material 5B for the retaining wall of the right side wall 2, and backfilling. Alternatively, there is a construction yard In some cases, the left span portion and the right span portion may be constructed at the same time after arranging a normal intermediate wall in which the steel material does not extend upward from the upper end surface.

In the third step, when placing the concrete for the bottom slab 4, the lower end surface of the precast concrete intermediate wall or intermediate pillar 15 is positioned above the bottom surface of the bottom slab so that the placed concrete is the precast concrete intermediate wall or intermediate pillar. It is desirable to be able to arrange the reinforcement continuously without interruption at 15 parts.

[Other form examples]
(1) In the above embodiment, the top slab 3 is constructed after excavating and removing the ground up to the position where the top slab between the precast concrete side walls 2, 2 is to be constructed. In the case of crossing, the top slab 3 may be constructed while installing a lining plate to block the excavation part and sequentially replacing the lining plate.

(2) In the above embodiment, both the precast concrete side wall 2 and the precast concrete intermediate wall or intermediate column 15 were provided with a plurality of steel piles 6 projecting downward from the lower end surface. The piles 6 may be eliminated and the entire embedded length may be precast concrete members.

(3) In the above embodiment, as shown in FIGS. 3 and 4, all the core materials (steel materials 5) arranged on the precast concrete side wall 2 extend upward from the upper end surface to the side of earth and water pressure. In the past, steel materials 5B for earth retaining walls were formed for directional resistance, but depending on the earth and water pressure, every other steel material 5 or more than every other steel material 5 that extends upward from the upper end surface is used. The steel material 5 may not extend upward.

DESCRIPTION OF SYMBOLS 1A, 1B... Underground structure, 2... Precast concrete side wall, 3... Top plate part, 4... Bottom plate part, 5... Steel material, 5A... Steel material part for core material, 5B... Steel material part for retaining wall, 6... Steel pile

Claims (9)

A method for constructing an underground structure having at least both side wall portions, a top slab portion and a bottom slab portion,
A steel material is arranged as a core material in place of the main reinforcement in the construction part of the both side walls, and the steel material extends upward from the upper end surface and is a steel material for earth retaining wall for lateral resistance such as earth water pressure. The precast concrete side walls forming the main body structure are erected in the ground, and the ground between the precast concrete side walls is excavated to the position where the top slab is to be constructed. After that, the main body structure is formed between the precast concrete side walls. A first step of constructing the top plate and backfilling to complete the shallower part than the top plate in advance;
a second step of excavating the ground deeper than the top slab surrounded by the precast concrete side wall and the top slab, and finally excavating to the construction depth of the bottom slab;
and a third step of placing concrete in a bottom slab construction site and connecting and integrating with the precast concrete side walls to construct the bottom slab that will be the main body structure. construction method. A method for constructing an underground structure having both side walls, an intermediate wall or intermediate pillar between both side walls, a top slab and a bottom slab,
In each span partitioned by the side walls, the intermediate wall between the side walls, or the intermediate column, a steel material is arranged as a core material instead of the main reinforcement in the construction part of the side wall, and the steel material is above the upper end surface. The precast concrete side wall that forms the main structure, which extends to the side and forms the steel part for the earth retaining wall for lateral resistance such as soil water pressure, is erected in the ground, and the intermediate wall or intermediate pillar construction part , a main body structure in which a steel material is arranged as a core material instead of the main reinforcement, and the steel material extends upward from the upper end surface to form a steel material part for an earth retaining wall for lateral resistance such as earth and water pressure; A precast concrete intermediate wall or intermediate pillar is erected in the ground, and after excavating and removing the ground up to the position where the top slab is constructed between these spans, the top slab that will be the main structure is constructed between the precast concrete side walls. , a first step of preliminarily completing a shallow portion below the top plate portion by backfilling;
a second step of excavating the ground deeper than the top slab surrounded by the precast concrete side walls and the top slab, and finally excavating to the construction depth of the bottom slab;
and a third step of placing concrete in the bottom slab construction site and connecting and integrating the precast concrete side wall and the precast concrete intermediate wall or intermediate pillar to construct the bottom slab that will be the main body structure. A method of constructing an underground structure, characterized by: 3. The method of constructing an underground structure according to claim 1, wherein said steel material, which is a core material of said precast concrete side wall, is arranged instead of a ground-side main reinforcement. A T-shaped steel is used as the steel material, and the T-shaped steel is arranged so that the flange portion faces the outer surface side of the precast concrete side wall and the web portion protrudes inward. Construction method of underground structure according to claim 1. The precast concrete side walls and/or the precast concrete intermediate walls or intermediate columns are provided with a plurality of steel piles projecting downward from the lower end surface for lateral resistance such as vertical bearing capacity and earth and water pressure. 5. The method for constructing an underground structure according to any one of 1 to 4. The underground structure according to any one of claims 1 to 5, wherein the precast concrete side wall and/or the precast concrete intermediate wall or intermediate column has a film pasted or a release agent applied to at least the inner wall surface side. construction method. A steel material is arranged as a core material instead of the main reinforcement, and the steel material extends upward from the upper end surface to form a steel material part for retaining walls for lateral resistance such as earth and water pressure, and vertical bearing capacity. And a precast concrete side wall provided with a plurality of steel piles projecting downward from the lower end surface for lateral resistance such as earth and water pressure, a top slab provided at the upper part between the precast concrete side walls, An underground structure characterized by comprising a bottom slab portion which is provided at a lower portion between precast concrete side walls and which is constructed of cast-in-place concrete. One or a plurality of precast concrete intermediate walls or intermediate columns are provided between the precast concrete side walls, and the precast concrete intermediate walls or intermediate columns have a steel material as a core material instead of a main reinforcement, and the steel material is placed on top. Extends upward from the end surface to form a steel material part for retaining walls for lateral resistance such as earth and water pressure, and protrudes downward from the bottom end surface for vertical bearing capacity and lateral resistance such as earth and water pressure 8. An underground structure according to claim 7, wherein a plurality of steel piles are provided so as to A steel material is arranged as a core material instead of the main reinforcement, and the steel material is arranged to extend upward from the upper end surface to form a steel material part for an earth retaining wall for lateral resistance such as earth and water pressure. A precast concrete side wall or a precast concrete intermediate wall/column, characterized in that a plurality of steel piles are provided so as to protrude downward from an end face.

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