Method for constructing underground continuous wall and underground continuous wall

Abstract

To provide a method for constructing an underground continuous wall and an underground continuous wall which can efficiently remove a part of an underground continuous wall later.SOLUTION: An underground continuous wall 30 is constructed by embedding a plurality of core materials 31 and 32 separated from each other in a soil cement. The core material 32 includes a steel part 32s which is H-shaped steel of a first part composed of a steel material, and a fiber part 32f as a second part composed of a fiber material which is easier to be cut than the steel material. The steel part 32s below the core material 32 is partially built in an arrangement scheduled region of the core material 32 where the soil cement is stored, and then the core material 32 is embedded in the soil cement, while forming the core material 32 by joining the upper end of the steel part 32s and the lower end of the lifted fiber part 32f.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for constructing a diaphragm wall formed by burying a plurality of spaced apart H-shaped steel beams in soil cement, and the diaphragm wall. [Background technology]

[0002] Conventionally, there is known a diaphragm wall (SMW method diaphragm wall) constructed by embedding a plurality of spaced core materials in soil cement (see, for example, Patent Document 1). The method of constructing a diaphragm wall described in this document includes a soil cement formation process in which the ground is drilled while injecting and stirring cement milk to form soil cement, and an erection process in which a case body is erected in the soil cement before the soil cement hardens. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-106231 A Summary of the Invention [Problem to be solved by the invention]

[0004] A new structure may be constructed on land where an existing structure has been demolished. In this case, the tunnel that connects the utility conduit under the road to the existing structure is blocked when the existing structure is demolished. After that, the newly constructed structure is connected to the blocked tunnel. If the above-mentioned diaphragm wall is formed between this new structure and the tunnel, the part connecting the new structure and the tunnel must be formed in the diaphragm wall. In this case, the core material embedded in the diaphragm wall is usually made of H-shaped steel. For this reason, it was necessary to cut the H-shaped steel to connect the new structure to the tunnel. However, because H-shaped steel is hard, it is difficult to cut H-shaped steel. This took time and effort. [Means for solving the problem]

[0005] A method of constructing an underground continuous wall that solves the above-mentioned problems is a method of constructing an underground continuous wall by embedding a plurality of spaced-apart core materials in soil cement, wherein the plurality of core materials have a first part made of steel and a second part made of a fibrous material that is easier to cut than the steel, and one of the lower parts of the first and second parts of the core material is partially erected in an area in which the core material is intended to be placed, in which the soil cement is contained, and then the core material is formed by joining an upper end of the one part to a lower end of the other of the first and second parts which are lifted up, while the core material is embedded in the soil cement.

[0006] In addition, an underground continuous wall that solves the above-mentioned problems is an underground continuous wall formed by embedding a plurality of spaced-apart core materials in soil cement, the plurality of core materials having a first portion made of steel material and a second portion made of a fiber material that is easier to cut than the steel material. Effect of the Invention

[0007] According to the present invention, a portion of the diaphragm wall can be efficiently removed later. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a front view of a main part illustrating the core material of a diaphragm wall in an embodiment. [Diagram 2] FIG. 2 is a plan view of a main part of a building according to an embodiment. [Diagram 3] FIG. 3 is a vertical cross-sectional view taken along line 3-3 in FIG. 2. [Figure 4] This is a vertical cross-sectional view of a main part of a building with an existing sleeve removed in an embodiment. [Diagram 5] FIG. 2 is a vertical cross-sectional view of a main part in an embodiment where backfill soil is provided adjacent to a diaphragm wall. [Figure 6] FIG. 2 is a vertical cross-sectional view of a main part in a state where a new body is formed in an embodiment. [Figure 7] FIG. 2 is a vertical cross-sectional view of a main part of a diaphragm wall in an embodiment after a horizontal hole has been formed therein. [Figure 8] 1 is a vertical cross-sectional view of a main portion of an embodiment in which a new sleeve pipe is placed in a horizontal hole formed in a diaphragm wall. FIG. [Figure 9] FIG. 2 is an explanatory diagram illustrating the placement of a core material embedded in a diaphragm wall in an embodiment. [Figure 10] FIG. 2 is an explanatory diagram illustrating the placement of a core material embedded in a diaphragm wall in an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a concrete embodiment of a diaphragm wall construction method and a diaphragm wall will be described with reference to Figs. 1 to 10. Fig. 1 is a vertical cross-sectional view of a diaphragm wall 30 in an embodiment. The diaphragm wall 30 in this embodiment is formed by the SMW method (soil cement diaphragm wall construction method). This diaphragm wall 30 is constructed by burying a plurality of core materials 31, 32, each having an H-shaped horizontal cross section, at a distance from each other in soil cement, which is prepared by mixing and stirring soil and cement slurry in situ. In Fig. 1, dotted portions indicate areas where hardened soil cement is exposed.

[0010] In this embodiment, two types of core materials 31, 32 are used. The core material 31 is an H-shaped steel made of iron material (steel material) such as rolled steel material for general structure (SS material) or rolled steel material for welded structure (SM material). The core material 32 is composed of a fiber portion 32f located in the center as a second portion, and steel portions 32s as a first portion disposed above and below the fiber portion 32f.

[0011] The steel portion 32s is a member (H-shaped steel) made of an iron material (steel material) similar to the core material 31 and having an H-shaped cross section. The fibrous portion 32f is made of a fibrous material that is easier to cut than the steel portion 32s. Specifically, the fiber portion 32f is a member having an H-shaped horizontal cross section, which is made of FRP (fiber reinforced plastic) formed by mixing carbon fiber. As the FRP in this embodiment, Nefmac (New Fiber material for Reinforcing Concrete), which is a composite material for reinforcing concrete, is used, which is made by integrally forming high-performance continuous fibers such as carbon fiber and glass fiber into an H-shape while impregnating them with a resin having excellent chemical resistance.

[0012] The fiber portion 32f is arranged so as to include a range in which a through hole h1, which is a horizontal hole described later, is formed. This through hole h1 is formed by excavating the diaphragm wall 30 to connect to the tunnel 15. In addition, in Fig. 1, the flange portions of the H-shaped core materials 31, 32 are shown lined up in a spaced-apart state.

[0013] (Method of connecting tunnel 15, which was connected to existing structure A1, with new structure A2) Next, a construction method for connecting the new structure A2, which has the underground continuous wall 30 of the above-mentioned configuration arranged around it, to the tunnel 15 that was connected to the existing structure A1 to be demolished will be described.

[0014] Fig. 2 is a plan view of the existing structure A1 and diaphragm wall 21 before the new structure A2 is constructed, and Fig. 3 is a vertical cross-sectional view taken along line 3-3 in Fig. 2. The diaphragm wall 30 will be constructed at the dotted portion in Fig. 2.

[0015] As shown in Fig. 2, the diaphragm wall 21 is formed on the outside of the existing structure A1 when the existing structure A1 is constructed. The diaphragm wall 21 is constructed by the OWS method. In this embodiment, the diaphragm wall 21 and the existing structure A1 are demolished, and a new diaphragm wall 30 and a new structure A2 are constructed.

[0016] A utility conduit 11 provided under a general road is connected to the existing diaphragm wall 21 via a tunnel 15. The tunnel 15 is provided with a cylindrical Hume pipe 15H that is buried so as to extend horizontally. 3, the existing structure A1 is connected to the inside of the Hume pipe 15H of the tunnel 15 via a plurality of existing sleeve pipes st1. The existing sleeve pipes st1 penetrate the existing wall 23 and are connected to the existing structure A1.

[0017] During dismantling, the first step is to remove the existing sleeve pipe. Specifically, as shown in Fig. 4, a plurality of core holes including a part of the peripheral end portion of each existing sleeve pipe st1 are formed so as to be continuous, whereby each existing sleeve pipe st1 is removed.

[0018] Next, an iron plate 27 is placed on the surface of the removed existing sleeve pipe st1 opposite to the tunnel 15. In this way, the iron plate 27 closes the existing wall 23 on the side of the existing structure A1. After that, the reinforced concrete parts of the existing structure A1, such as underground columns 25 (Figure 2) and beams, are removed. Then, as shown in FIG. 4, the removed reinforced concrete portion is backfilled with liquefied treated soil 26.

[0019] Next, the basement of the existing structure A1 is demolished. In this case, a diaphragm wall 30 is formed inside the building (on the left side of the figure) from the liquefied treated soil 26. The construction method of this diaphragm wall 30 will be described in detail later. The shape of the diaphragm wall 30 when viewed from the left side of the formed diaphragm wall 30 is as shown in FIG. 1.

[0020] 5, soil is backfilled into the space of the demolished underground framework inside the diaphragm wall 30. As a result, backfill soil 41 is placed adjacent to the diaphragm wall 30. After that, a primary excavation is carried out.

[0021] Next, after the second excavation, construction work on the second basement floor slab, drop walls, etc. will be carried out. Furthermore, after the third excavation, construction work on the third basement floor slab, drop walls, etc. will be carried out. As shown in Fig. 6, a wall skeleton 42 of a new skeleton A2 is formed in the backfill soil 41 that was located next to the diaphragm wall 30 through skeleton construction. A space area 42A is formed in the wall skeleton 42. The space area 42A is formed at a position corresponding to the tunnel 15.

[0022] Next, in the space region 42A of the wall structure 42, construction work for penetrating the underground exterior wall is carried out. As shown in Fig. 7, in this construction, first, a plurality of through holes h1 are formed in the diaphragm wall 30 and the liquefied treated soil 26. Each through hole h1 is formed in a portion corresponding to the tunnel 15. These through holes h1 are excavated using the baby mould method through the fibrous part 32f (shown in Fig. 1) of the core material 32 of the diaphragm wall 30 and the hardened soil cement. Furthermore, holes of a size corresponding to the through holes h1 are also formed in the iron plate 27 (shown in Fig. 7).

[0023] Next, as shown in Fig. 8, a sleeve pipe st2 is placed in the formed through hole h1. This sleeve pipe st2 penetrates from the Hume pipe 15H of the passage 15 to the wall body 42. In this case, the sleeve pipe st2 also penetrates the through hole h1. Then, the sleeve pipe st2 is fixed by injecting grout around its outer periphery.

[0024] Next, construction work for the connecting wall 43 on the third basement floor is carried out in the space area 42A of the wall skeleton 42. After that, various piping such as electric conduits, gas pipes, and sewer pipes are arranged inside the sleeve pipe st2. As a result, the inside of the new skeleton A2 and the space of the Hume pipe 15H of the tunnel 15 are connected to each other.

[0025] (Method of forming underground diaphragm wall 30) Next, a method for forming the diaphragm wall 30 will be described with reference to Figures 9 and 10. In this embodiment, the core material 32 is formed by joining the steel portion 32s and the fiber portion 32f while erecting the core material 32.

[0026] FIG. 9 shows a state in which the steel part 32s at the bottom of the core material 32 has been lowered into the intended arrangement area E1, and FIG. 10 shows a state in which the steel part 32s and the fiber part 32f above it have been joined. Here, with reference to FIG. 9, first, a method of forming the diaphragm wall 30 up to the stage before the steel section 32s shown in FIG. 9 is placed in the intended placement area E1 will be described.

[0027] First, as in the conventional method, an area in the ground where the diaphragm wall 30 is to be constructed is excavated. Specifically, the planned arrangement area E1 in FIG. 9 is formed by excavation. This planned arrangement area E1 is an area that is long in the vertical direction according to the size of the diaphragm wall 30 and is also long in the direction perpendicular to the paper surface of the figure. In this case, as shown in the figure, the upper part of the planned arrangement area E1 may be shaped to become wider toward the top.

[0028] Then, cement is injected into the soil obtained when the intended placement area E1 is excavated underground, and the soil is then mixed and stirred to fill (contain) the intended placement area E1 with the soil cement S1. Next, a core material setting ruler 51 is placed around the upper opening of the planned arrangement area E1. This core material setting ruler 51 has a rectangular frame shape and is formed by connecting the ends of four H-shaped steels. A guide jig 55 for guiding the core materials 31, 32 is provided on this core material setting ruler 51. The guide jig 55 includes two H-shaped steels 56 placed on the core material setting ruler 51 and two angle bars 57 placed on these H-shaped steels 56. The two H-shaped steels 56 and the two angle bars 57 are placed at a distance apart according to the size of the core materials 31, 32 to be inserted. The two angle bars 57 are placed so as to extend in a direction perpendicular to the H-shaped steel 56.

[0029] When the core material 31 is to be placed in the intended placement area E1, construction similar to that of the conventional method is carried out. Moreover, when the core material 32 is to be placed in the intended placement area E1, it is installed as follows. First, the steel part 32s of the core material 32 is lifted by a crane, placed above the intended arrangement area E1, and then lowered straight down. In this case, the steel part 32s is gradually lowered into the intended arrangement area E1 while being guided by the guide jig 55.

[0030] At this time, when the upper end of the steel part 32s is lowered to a height where it is easy to work, the lowering is stopped once. Then, the splice plate 35 is attached to the flange part of the upper end of the steel part 32s with a high strength bolt (not shown).

[0031] Next, the fiber part 32f is lifted by a crane, placed above the steel part 32s, and then lowered straight down. In this case, the fiber part 32f is lowered until the lower end of the fiber part 32f abuts against the upper end of the steel part 32s.

[0032] 10, with the lower end of the fiber portion 32f and the upper end of the steel portion 32s in contact with each other, a splice plate 35 is attached to the flange of the fiber portion 32f with high-strength bolts (not shown). Furthermore, a splice plate 36 is attached to the web of the steel portion 32s and the fiber portion 32f with high-strength bolts (not shown).

[0033] Then, the upper part of the steel part 32s and the fiber part 32f joined above the steel part 32s are gradually lowered to the planned arrangement area E1. Then, when the upper end of the fiber part 32f reaches a height that is easy to work with, the steel part 32s is joined above the fiber part 32f in the same manner as when the fiber part 32f was joined to the steel part 32s. Specifically, the splice plate 35 attached to the flange part at the upper end of the fiber part 32f is attached to the flange part at the lower end of the steel part 32s that abuts against the upper end of the fiber part 32f, and the splice plate 36 is attached to the web part of the fiber part 32f and the steel part 32s. Then, the core material 32 of the steel part 32s joined above the fiber part 32f is gradually lowered to the planned arrangement area E1. As described above, the core material 32 with the steel part 32s joined below and above the fiber part 32f is buried in the soil cement S1 in the planned arrangement area E1. Thereafter, the soil cement S1 in which the core materials 31 and 32 are embedded is hardened.

[0034] Next, the soil cement is scraped away so that one flange portion of the core materials 31, 32 embedded in the soil cement is exposed. In this case, the soil cement is scraped away so that the flange portions of the core materials 31, 32 on the side (left side in FIG. 4) where the new structure A2 will be installed in the diaphragm wall 30 are exposed. As a result, the diaphragm wall 30 is formed with the flange portions of the core materials 31, 32 exposed, as shown in FIG. 1. Furthermore, a plurality of spaced stud bolts are joined to desired locations on the exposed flange portions of the core materials 31, 32.

[0035] (Action of this embodiment) In the core material 32 of the diaphragm wall 30, the region in which the through hole h1 is formed is made of the fibrous portion 32f which is easier to cut than the steel portion 32s, so the through hole h1 is formed by cutting this fibrous portion 32f.

[0036] According to this embodiment, the following effects can be obtained. (1) In this embodiment, in the core material 32 embedded in the diaphragm wall 30, a range including a region where the through hole h1 will be formed later is formed of the fibrous part 32f, which is easier to cut than an iron material (steel material). As a result, when the through hole h1 is formed, the fibrous part 32f, which is easier to excavate, is cut, so that the through hole h1 can be formed efficiently.

[0037] (2) In this embodiment, the upper and lower parts of the fiber part 32f of the core material 32 are made of steel parts 32s. Therefore, the part where the through hole h1 is not formed is made of hard steel parts 32s, so that the core material 32 can be made strong.

[0038] (3) In this embodiment, the core material 32 is constructed by joining the fiber portion 32f and the steel portion 32s when it is placed in the planned arrangement area E1. If the fiber portion 32f and the steel portion 32s are first joined to form a single core material, and then the core material is placed, a bending force is applied to the fiber portion 32f, which may destroy the fiber portion 32f. For this reason, by forming the core material 32 while joining the fiber portion 32f to the steel portion 32s during placement, it is possible to efficiently place the core material in the planned arrangement area E1.

[0039] This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction. In the above embodiment, the core material 32 of the diaphragm wall 30 is composed of the fiber part 32f and the steel parts 32s above and below the fiber part 32f. The configuration of the core material embedded in the diaphragm wall 30 is not limited to this. For example, depending on the position of the through hole, the core material may have steel parts above or below the fiber part.

[0040] Also, the entire core material, which has a portion to be cut to form a through hole, may be made of FRP. In this case, the core material 31 of the diaphragm wall 30 corresponds to the first portion, and the core material made entirely of FRP corresponds to the second portion.

[0041] In the above embodiment, the fiber portion 32f of the core material 32 of the diaphragm wall 30 is made of fiber reinforced plastic compounded with carbon fiber. The material of the fiber portion 32f is not limited to this, and the fiber portion 32f may be made of a material that is easier to excavate than the core material 31 of the H-shaped steel, for example, fiber reinforced plastic mixed with glass fiber.

[0042] In the above embodiment, the portion of the core material 32 of the underground diaphragm wall 30 that corresponds to the through hole h1 to be excavated is made of the fiber portion 32f. The portion where the fiber portion 32f is formed is not limited to the portion where the through hole h1 is formed, but may be provided in a location to be excavated for other purposes.

[0043] Next, the technical ideas that can be understood from the above embodiment and other examples will be described below. (a) the core material is a member having an H-shaped horizontal shape and having a web and flange portions connected to both ends of the web, 3. The method for constructing a diaphragm wall according to claim 1 or 2, characterized in that the hardened soil cement is scraped away so as to expose one flange portion of the core material. (b) A method for constructing a diaphragm wall according to claim 2, characterized in that the horizontal hole is the tunnel. [Explanation of symbols]

[0044] A1...existing structure, A2...new structure, E1...proposed area, h1...through hole, S1...soil cement, st1...existing sleeve pipe, st2...sleeve pipe, 11...utility sewer, 15...tunnel, 15H...Hume pipe, 21,30...underground diaphragm wall, 25...underground column, 26...liquefied treated soil, 27...steel plate, 31,32...core material, 32f...fiber part as second part, 32s...steel part as first part, 35,36...splice plate, 41...backfill soil, 42...wall structure, 42A...space area, 43...connecting wall, 51...core material installation ruler, 55...guide jig, 56...H-shaped steel, 57...angle iron.

Claims

1. A method for constructing a diaphragm wall by embedding a plurality of spaced apart core materials in soil cement, comprising: The plurality of core materials include a first portion made of a steel material and a second portion made of a fiber material that is easier to cut than the steel material, A method for constructing an underground continuous wall, characterized in that one of the lower parts of the first and second parts of the core material is partially erected in an area where the core material is intended to be placed and contains the soil cement, and then the core material is formed by joining the upper end of the one part to the lower end of the other of the lifted first and second parts, while burying the core material in the soil cement.

2. 2. The method for constructing a diaphragm wall according to claim 1, further comprising the step of forming a horizontal hole in the diaphragm wall by cutting the second portion of the core material.

3. A continuous underground wall formed by embedding a plurality of spaced apart core materials in soil cement, The plurality of core materials are characterized in that they comprise a first portion made of steel material and a second portion made of a fibrous material that is easier to cut than the steel material.

4. 4. The underground continuous wall according to claim 3, wherein at least one of the core members is formed by joining the first portion and the second portion.

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