JPH09100541A - Underground structure and asymmetric u-shaped steel sheet-pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize a piece of land, shorten a construction period of time and to reduce a construction cost in the construction of an underground structure. SOLUTION: A steel sheet pipe 1 used for earth retaining wall and bearing wheel in a basement is driven to the limit of a site boundary. The inside surrounded by a steel sheet pile continuous wall is excavated to form a space for the basement. The upper end of the steel sheet pile 1 is utilized as a continuous footing, shape steels 4 and 5 as foundation or floor beam are rigidly connected thereon, and a portal frame skeleton for part of the basement 10 is formed. A ground building is borne on a directly upper position of the steel sheet pile 1 through the shape steels 4 and 5. As the steel sheet pile 1, joint shapes of both ends are bilateral asymmetry, and cross sectional shapes are arranged in the same direction to use the asymmetrical U-shape steel sheet pile capable of being connected on a straight line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses an earth retaining sheet pile for excavation work as it is for a bearing wall such as a basement or a common groove, and also serves as a foundation for an upper structure such as an aboveground building, and an underground structure thereof. The present invention relates to an asymmetric U-shaped steel sheet pile suitable for constructing an underground structure.

[0002]

2. Description of the Related Art In the city center and its suburbs, basements and the like are often provided on a limited site in order to increase the living space of a building. When constructing a basement in this narrow site, it is especially difficult to secure a construction space, and the construction period is extended,
There are problems such as soaring costs.

For example, as a conventional basement construction method, as shown in FIG. 10, the ground at the basement 51 installation position is generally excavated by an open cut method.
Excessive excavation area 52 was large, and it was necessary to secure a considerable distance L between the site boundary and the outer wall surface of basement 51.

In order to deal with these problems, various construction methods have been proposed as a technique for constructing a basement.

In Japanese Patent Laid-Open No. 58-222219, a panel produced as a divided body of an outer wall of a basement or an integrally formed molded body of the outer wall is press-fitted into the ground improved ground, and the inside is excavated to form a basement. The construction method for constructing is described.

Further, in JP-A-60-13125, as shown in FIG. 11, a basement skeleton body 62 assembled with a precast concrete panel or the like and having a blade opening 63 at a lower end is directly press-fitted into the ground to press the basement. A method of constructing 61 is described.

Further, as an underground structure in which an underground wall doubles as a foundation of an above-ground building, in Japanese Patent Laid-Open No. 62-220663 and Japanese Patent Laid-Open No. 6-272264, the above-ground building is supported by a basement part made of precast concrete. The structure is described.

On the other hand, regarding a steel sheet pile used as a retaining wall, etc., when a U type steel sheet pile 91 which has been generally used conventionally is constructed by a vibro hammer or a hydraulic press machine,
As shown in FIG. 19, the web portion is chucked and placed by vibration or hydraulic pressure.

Conventionally, a general U-shaped steel sheet pile 91 has a bilaterally symmetrical cross-sectional shape in which joints 91a are formed at both ends, and the joints 91a are continuously connected by alternately inverting the inside and the outside. By doing so, the steel sheet pile wall 92 as a retaining wall is constructed, but at this time, due to the reason that the resistance of the joint portion and the ground resistance are large, etc., it rotates in the direction of the arrow in the figure and twists in the underground portion. It may occur (see FIG. 20).

When the constructed steel sheet pile wall 92 is used as a part of a wall of a basement or the like, the simplest method is to attach a dowel 93 or the like to the surface of the steel sheet pile wall 92 as shown in FIG. There is a method of placing concrete 94 on site.

In addition to this, Japanese Unexamined Patent Publication (Kokai) No. 5-140928 discloses an asymmetrical U-shaped steel sheet pile in which the joint shape at both ends of the U-shaped steel sheet pile is left-right asymmetrical and the cross-sectional shapes are aligned in the same direction so that they can be joined in a straight line. Have been described.

[0012]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The construction methods described in JP-A-222219 and JP-A-60-13125 can be installed even if the site is small.
It is said that by excavating and excavating only the inside of the basement side, there is no need for extra digging or earth retaining outside the basement, and the construction period and cost will be reduced.

However, in the case of an underground wall made of precast concrete, it is necessary to make the wall thickness as thick as about 150 to 200 mm from the viewpoint of preventing water from penetrating into the basement.
Weight also increases. Further, the friction resistance of the soil when it is press-fitted in the soil is large, and there is a problem in the work such as lifting a large precast concrete panel.

In addition to this, the precast concrete basement has a problem in that the shape of the basement is inferior in terms of the degree of freedom, because the shape of each component is limited and the weight becomes larger than that of the steel basement.

Regarding the structure in which the aboveground building is supported by the basement part made of precast concrete, the above-mentioned Japanese Patent Laid-Open No.
In the case of the structures described in JP-A-2-220663 and JP-A-6-272264, the cloth foundation of the above-ground building also serves as a precast concrete panel or block serving as a wall of the basement. Under the present circumstances, as such an underground structure material that also serves as a foundation, it has not yet been applied to anything other than precast concrete products.

On the other hand, as an example in which the basement is made of steel, there is a device described in Japanese Utility Model Laid-Open No. Sho 63-100542, but in this case as well, the cloth foundation is installed in a portion without the basement, and the load directly on the aboveground building is steel. The structure does not affect the structure of the basement.

INDUSTRIAL APPLICABILITY The underground structure of the present invention can expand the effective space of the land to fill the boundary of the site even in a small site, can reduce the amount of earth retaining excavation for building an underground structure such as a basement, and the retaining wall By solving these problems, it is possible to directly apply to the outer wall of the basement, the retaining wall can also serve as the foundation of the superstructure such as the above-ground building, and the retaining wall has high rigidity as the outer wall of the basement. , Effective use of land, shortening construction period, and reducing construction cost.

Regarding the steel sheet pile used for constructing the underground structure, the U-shaped steel sheet pile 91 meanders as shown in FIG. There is a problem of shortening. In particular, the influence is great in the underground part, and when excavating the front surface of the steel sheet pile, the flatness of the wall surface is significantly deteriorated.

When constructing a temporary earth retaining wall or a revetment, etc., some construction error is allowed for the normal distance, but if rotation or twisting occurs during casting, The normal distance becomes short, and it takes time and effort to place the wire so that the normal distance extends.

Further, when the steel sheet pile is driven in a narrow space, or particularly when the front surface of the steel sheet pile is excavated and used as an underground wall, it is necessary to consider the construction error due to rotation and twist in the underground part in advance. There is. Considering this construction error, it is necessary to increase the thickness of the underground wall, and the area required for constructing the underground wall becomes large, so the usable site area becomes narrow and it is uneconomical.

Further, in the case of the conventional U-shaped steel sheet pile 91, FIG.
As shown in FIGS. 9 to 21, since the joint 91a is located at the center of the wall of the earth retaining wall 92, a bending load exerts a longitudinal shearing force on the joint, and the adjacent steel sheet piles 91 may not work together. Conceivable. To deal with this, it is uneconomical to consider the reduction of the sectional performance of the steel sheet pile (joint efficiency) at the time of design.

Further, in the conventional U-shaped steel sheet pile 91, since the joint portion is exposed on the wall surface, when it is used as a retaining wall or a seawall of the main structure, there is a problem that its landscape is impaired.

The asymmetric U-type steel sheet pile of the present invention is a steel sheet pile suitable for constructing an underground structure according to the present invention, and at the same time solves the above problems.

[0024]

In the underground structure according to claim 1 of the present application, an underground space is formed in an interior surrounded by a steel sheet pile that also serves as a retaining wall and a bearing wall of a basement. The upper end of the structure is a cloth foundation that supports the load of the upper structure.

The steel sheet pile is used not as a temporary structure but as a structural material for forming a self-standing earth retaining continuous wall as it is buried and forming an outer wall of a basement or the like having a water stopping function. The underground space can maximize the effective space by excavating the area surrounded by the steel sheet pile.

Further, the steel sheet pile is made to function as a pile capable of sufficiently supporting the load of the upper structure, and the upper end thereof is also used as the cloth foundation of the upper structure such as an aboveground building.

The invention according to claim 2 is the underground structure according to claim 1, wherein a precast concrete block (panel or the like) is provided on the underground space side surrounded by the steel sheet pile, and the steel sheet pile and the precast concrete block are connected and integrated. This is limited to the case of using a cloth foundation that supports the load of bearing walls and superstructures such as basements.

The connection and integration of the steel sheet pile and the precast concrete block can be performed by fastening bolts or the like, and by integrating the precast concrete block, the steel sheet pile as a wall of a basement or the like can be reinforced.

Further, due to the influence of groundwater, a vertically upward force due to buoyancy may act on the basement or the like, but the weight of the precast concrete block can be resisted against this buoyancy to provide an anchor effect.

On the other hand, when it is difficult to support the vertical downward load of the upper structure with only the steel sheet pile, the pressure receiving area of the ground is increased by the precast concrete block, the supporting proof strength is increased, and a stable underground structure is constructed. To be done.

As described above, the steel sheet pile and the precast concrete block are provided side by side and integrated with each other, so that it is possible to improve the water-stopping property of the basement or the like, the heat insulating property, and the vertical supporting force of the steel sheet pile.

The invention according to claim 3 is the invention according to claim 1 or 2.
With respect to the underground structure according to (1), the case where the gate-shaped frame frame is formed by limiting the shape steel on the upper end of the steel sheet pile and rigidly contacting the shape steel with the steel sheet pile is limited.

Shaped steels such as H-shaped steel, CT-shaped steel (cut tee), chevron steel, grooved steel, and I-shaped steel as a base or floor beam so as to connect the entire circumference and opposite sides of the steel sheet pile. By making a rigid contact with, it is possible to increase the rigidity of the steel basement, etc.
It is also possible to adjust the height of the fabric foundation of the superstructure.

According to a fourth aspect of the present invention, in the inventions of the first to third aspects, the steel sheet pile is a steel sheet pile having a U-shaped cross section, and the joint shapes at both ends are asymmetric, and the cross section shape is the same. This limits the use of steel sheet piles that are aligned in the same direction and can be joined in a straight line.

The steel sheet pile according to claim 4 is disclosed in
Corresponding to the asymmetrical U-shaped steel sheet pile described in Japanese Unexamined Patent Publication No. 140928, in addition to workability and ease of manufacturing by rolling, the cross-sectional shapes can be aligned in the same direction and can be joined in a straight line, so that the site limit is filled. It has the advantage of being able to secure a larger basement space.

An asymmetrical U-shaped steel sheet pile according to claim 5 of the present application is a further improvement of the asymmetrical U-shaped steel sheet pile described in the above-mentioned Japanese Patent Laid-Open No. 5-140928. In the asymmetrical U-shaped steel sheet pile in which the joint shape in the joint part is asymmetrical and the cross-sectional shapes are aligned in the same direction and can be joined in a straight line, flat parts in the same direction as the driving normal are located near the joint parts at both ends. It is configured such that the joint portion and the flat portion are located on the same straight line at the outermost edge of the sheet pile wall.

By providing the flat portion, it is possible to suppress the rotation and twisting of the underground portion at the time of driving, improve the driving performance, and construct the sheet pile wall with high construction accuracy.

The invention according to claim 6 is such that one of the joint portions at both ends of the asymmetrical U-shaped steel sheet pile of claim 5 is formed inward and the other is outward, and is exposed on the inner surface of the outermost edge of the sheet pile wall. This is limited to the case where they are engaged with each other in the non-operating position.

In this case, when the steel sheet pile wall is constructed, the joint portion is not exposed to the wall surface and becomes a flat wall surface, so that it is easy to set up the upset and the space can be effectively used. In addition, the landscape of the steel sheet pile wall surface is improved.

The asymmetrical U-shaped steel sheet pile according to the present invention is suitable for constructing the underground structure according to the present invention, but its use is not limited to this.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of an underground structure of the present invention, in which a steel sheet pile continuous wall formed by casting a steel sheet pile 1 at the boundary of a site covers four rounds. After fastening and excavating the area surrounded by the steel sheet pile continuous wall,
The steel sheet pile 1 is used as it is as the outer wall of the basement 10.

As for the entire circumference of the upper end and the opposite side of the steel sheet pile continuous wall, as shown in FIG. 3, shaped steels 4 and 5 such as H-shaped steel as a foundation or floor beam are arranged and connected, and the basement 10 portion is reversed. Rigidity is enhanced by forming a gate-shaped frame frame. FIG. 7 shows this inverted gate type rigid frame structure as a structural model diagram.

In the figure, 2 is gravel laid on the bottom of the excavated basement, 3 is base concrete placed on the gravel,
6 is a precast concrete plate attached to the lower surface of the shaped steel 5 as a floor beam.

The connecting portion of the steel sheet pile 1 is provided with a waterproof treatment material 7 (waterproof coating or water blocking material) in order to prevent intrusion of groundwater.
A heat insulating material 9 is installed inside the waterproofing material 7 and the ceiling of the basement 10.

The above-ground building portion is installed right above the steel sheet pile continuous wall, and the steel sheet pile 1 itself has a role of a cloth foundation. In the figure, 11 is the first floor of the above-ground building, and 12 is the second floor.

In this way, the steel sheet pile 1 functions as a retaining wall for constructing the basement 10, a bearing wall structural material for the basement 10 main body, and a cloth foundation for the above-ground building, so that the basement structure is greatly simplified. You can

FIG. 2 shows another embodiment of the underground structure of the present invention. For example, in the case of constructing the underground room 10 in a place where the ground surface is soft and water is likely to spring, the rigidity of the underground structure is improved. In order to improve the water stopping performance against groundwater and to prevent the underground room 10 from floating, a precast concrete block 21 is installed on the inner surface side of the steel sheet pile continuous wall, and the steel sheet pile continuous wall is connected by a fixing bracket 22 such as a high strength bolt to be integrated. It is an example.

In this example, as the precast concrete block 21, a unit in which the wall portion and the floor portion are integrated is used.

FIGS. 4 to 6 show a method of connecting the shaped steel 4 and mounting the height of the shaped steel 4 when the shaped steel 4 is mounted on the upper end portion of the steel sheet pile continuous wall as the foundation of the aboveground building. .

Since the height of the upper end of the continuous wall of the steel sheet pile must match the horizontal level of the four circumferences, two taper liner plates 32a and 32b are superposed and adjusted in this example. Bolt holes 33a are formed in the upper liner plate 32a, and elongated holes 33b are formed as bolt holes in the lower liner plate 32b. When tightening and fixing with bolts 34, the lower liner plate 32b is indicated by an arrow in the figure. By moving in the direction, the height can be finely adjusted.

FIG. 8 shows the basic shape of the steel sheet pile 1 used in the present invention, which corresponds to the steel sheet pile of the invention described in JP-A-5-140928. This steel sheet pile 1
Is characterized by its joint shape, which makes it easy to work in narrow spaces and shortens work.

FIG. 9 shows a state in which the steel sheet piles 1 have been cast up to the limit of the adjacent site, and the joint 41 of the steel sheet pile 1 is shown.
Since the shapes of a and 41b are left-right asymmetrical and the cross-sectional shapes are aligned in the same direction and joined in a straight line to construct a sheet pile wall, it is possible to carry out construction at the site limit. In addition, in the figure, a dotted line portion shows a pile driver occupying range 43 for driving the steel sheet pile 1.

FIG. 12 shows the overall shape of the steel sheet pile 71 in one embodiment of the asymmetrical U-shaped steel sheet pile according to the present invention.
Shows a joint portion thereof, and FIG. 14 shows a sheet pile wall 72 formed by continuously connecting asymmetric U-shaped steel sheet piles.

In the asymmetrical U-shaped steel sheet pile 71, the shape of the central portion of the cross section is U-shaped, the joint shapes of the joints 71a and 71b at both ends are left-right asymmetrical, and the cross-sectional shapes are aligned in the same direction so that they can be joined in a straight line. There is.

Near the joints at both ends of this asymmetrical U-shaped steel sheet pile 71, there are flat portions 71c in the same direction as the driving normal.
Is formed, and the joint portion and the flat portion 71c with which the joints 71a and 71b are engaged with each other are located on the same straight line at the outermost edge of the sheet pile wall 72.

Further, in this embodiment, one joint 7
1a is the outermost edge of the sheet pile wall 72 (corresponding to the front surface on the excavation side)
On the other hand, the other joint 71b is formed inwardly and outwardly so that they can be engaged with each other without being exposed to the wall surface of the sheet pile wall 72, as shown in FIG. Further, a protrusion 73 for restraining the rotation of the joint portion is provided on the inward facing joint 71a side.

In the asymmetric U-shaped steel sheet pile 71 of the present invention, when the steel sheet pile 71 is driven by a hydraulic press-fitting machine or a vibro hammer, the flat portion 71c can be chucked and driven as shown in FIG. Becomes This flat part 71
Since c is located on the same line as the joint portion in the direction of the driving normal, that is, is not planarly displaced from the joint portion which is the center of rotation generated during the driving, the driving portion acting on the chucking portion 81 It is possible to prevent the steel sheet pile 71 from rotating due to force.

Even if there are obstacles such as gravel in the underground portion, the flat portion 71c of the asymmetric U-shaped steel sheet pile 71 according to the present invention resists the acting force in the rotating direction in the underground portion. This has the effect of suppressing the rotation and twisting of the central portion (see FIG. 16). FIG. 17 shows, as another embodiment, a case where concrete 74 is placed on the front surface of the steel sheet pile wall 72 constituted by the asymmetrical U-shaped steel sheet pile 71 according to the present invention on the excavation side and used as the underground wall 75. , It can function as a steel-concrete composite structure and can effectively use space.

FIG. 18 shows still another embodiment in which a heavy anticorrosion coating 76 is applied to the surface of the asymmetrical U-shaped steel sheet pile 71 in order to improve the landscape of the steel sheet pile wall.

Incidentally, in the case of the conventional Z type steel sheet pile 97 in which the joint 97a is located at the outermost edge of the wall as shown in FIG. 22, it is necessary to fit the two Z type steel sheet piles 97 before driving. In the case of the asymmetrical U-shaped steel sheet pile according to the present invention, since the joint shape is asymmetrical, but the overall shape of the U-shaped portion is symmetrical, there is no need to perform work for fitting before placing.

[0061]

EFFECTS OF THE INVENTION According to the underground structure of the present invention, the underground structure to be constructed can be installed at the boundary of the site, and the effective space of the land can be expanded. Further, since the self-supporting earth retaining wall is constructed by placing steel sheet piles, the amount of excavation when constructing an underground structure of the same size can be reduced as compared with the open cut construction method and the like. Further, since the steel sheet pile serves both as the outer wall of the underground structure such as the basement and the cloth foundation of the upper structure such as the above-ground building, the construction material can be reduced, and thus the construction period can be shortened and the construction cost can be reduced.

According to the second aspect of the present invention, when the vertical supporting force of the steel sheet pile is insufficient due to soft ground or the like, the effect of improving the load-bearing capacity and improving the waterproofness of the basement can be obtained by integrating with the precast concrete block. In addition to being used, it also serves as a measure against buoyancy.

According to the third aspect of the present invention, the rigidity of the underground structure can be improved by forming the gate-shaped rigid frame by the steel sheet pile and the shaped steel rigidly contacting the upper end thereof.

According to the invention of claim 4, the construction of the boundary of the site is possible because of the shape of the steel sheet pile, and is further effective in expanding the effective space of the land.

According to the asymmetric U-shaped steel sheet pile according to the present invention, it is possible to suppress the rotation and twisting of the underground part during the driving, improve the driving performance, and construct the sheet pile wall with high construction accuracy. . Further, since the joint portion is located at the outermost edge of the sheet pile wall, the joint efficiency does not decrease and it is economical.

In the invention according to claim 6, when the sheet pile wall is constructed, the joint portion becomes a flat wall surface without being exposed to the wall surface, so that it is easy to set up the abdomen and the space can be effectively used. . In addition, the landscape of the steel sheet pile wall surface is improved.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing an embodiment of an underground structure of the present invention.

FIG. 2 is a vertical sectional view showing another embodiment of the underground structure of the present invention.

FIG. 3 is a perspective view showing a connection arrangement of steel sheet piles and shaped steel in an embodiment of the present invention.

FIG. 4 is a front view showing an example of a height adjusting method of a shaped steel as a base connected to an upper end of a steel sheet pile.

5 is a side view corresponding to FIG. 4. FIG.

FIG. 6 is a side view showing details of height adjustment of the shaped steel and a perspective view of a liner plate.

FIG. 7 is a structural model diagram in the embodiment of the underground structure of the present invention.

FIG. 8 is a plan view showing an example of the shape of a steel sheet pile used in the present invention.

FIG. 9 is a plan view showing an example of a soil retaining method using a steel sheet pile used in the present invention.

FIG. 10 is a vertical cross-sectional view showing a method of constructing a basement by a conventional open cut method.

FIG. 11 is a vertical cross-sectional view showing an example of a method for constructing a basement by a conventional precast concrete submersible method.

FIG. 12 is a plan view showing the overall shape of one embodiment of the asymmetric U-shaped steel sheet pile of the present invention.

13 is a plan view showing an engaged state of a joint portion corresponding to the embodiment of FIG.

FIG. 14 is a plan view showing a sheet pile wall in which asymmetric U-shaped steel sheet piles of the present invention are continuously provided.

FIG. 15 is a plan view for explaining a placing method by chucking a flat portion.

FIG. 16 is a plan view for explaining the effect of suppressing the occurrence of rotation and twist in the underground portion during driving.

FIG. 17 is a cross-sectional view showing another embodiment of the asymmetric U-shaped steel sheet pile of the present invention.

FIG. 18 is a plan view showing still another embodiment of the asymmetric U-shaped steel sheet pile according to the present invention.

FIG. 19 is a plan view for explaining the generation of rotation and twist in driving a conventional U-shaped steel sheet pile.

FIG. 20 is a plan view for explaining meandering in a sheet pile wall using a conventional U-shaped steel sheet pile.

FIG. 21 is a transverse cross-sectional view for explaining a case where a steel sheet pile wall made of a conventional U-shaped steel sheet pile is used as a part of a wall of a basement or the like.

FIG. 22 is a plan view for explaining a joint structure in a conventional Z type steel sheet pile.

[Explanation of symbols]

1 ... steel sheet pile, 2 ... laying gravel, 3 ... base concrete, 4
... Shaped steel (base), 5 ... Shaped steel (floor beam), 6 ... Precast concrete plate, 7 ... Waterproofing material, 8 ... Shaped steel, 9 ... Heat insulating material, 10 ... Basement, 11 ... First floor part, 12 ... 2nd floor,
21 ... Precast concrete block, 22 ... Fixing hardware, 31 ... Steel plate, 32a ... Upper liner plate, 32
b ... Lower liner plate, 33a ... Bolt hole, 33b ...
Long holes, 34 ... Bolts, 35 ... Fixing fittings, 41a, 41b
… Joints, 42… Sheet wall, 43… Pile driver occupation range, 71
... Asymmetric U-shaped steel sheet pile, 71a, 71b ... Joint, 71c ...
Flat part, 72 ... Sheet pile wall, 73 ... Protrusion, 74 ... Concrete, 75 ... Underground wall, 76 ... Heavy anticorrosion coating, 81 ... Chucking part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takuzo Nakazato 4-53 Kitahama, Chuo-ku, Osaka Sumitomo Metal Industries, Ltd. (72) Kenji Nonaka 4-53 Kitahama, Chuo-ku, Osaka Sumitomo Metal Industries, Ltd. (72) Inventor, Yutaka Kano 3 Hikari, No. 3, Hikaru, Kashima City, Ibaraki Prefecture Sumitomo Metal Industries, Ltd. Kashima Works

Claims (6)

[Claims] 1. An underground space is formed inside a steel sheet pile that also serves as a retaining wall and a bearing wall of an underground structure, and an upper space of the steel sheet pile serves as a cloth foundation to support the load of the upper structure. An underground structure characterized by being present. 2. A precast concrete block is provided alongside an underground space surrounded by the steel sheet pile, and the steel sheet pile and the precast concrete block are connected and integrated to support a load on a bearing wall and an upper structure of an underground structure. The underground structure according to claim 1, which constitutes a cloth foundation. 3. The underground structure according to claim 1 or 2, wherein a shaped steel as a base or floor beam is placed on the upper end of the steel sheet pile and is rigidly contacted with the steel sheet pile to form a gate-type rigid frame structure. . 4. The steel sheet pile has a U-shaped cross-section at the center.
Type steel sheet pile, the joint shape of both ends is asymmetrical,
The underground structure according to claim 1, 2 or 3, wherein the cross-sectional shapes are aligned in the same direction so that they can be joined on a straight line. 5. A non-symmetrical U-shaped steel sheet pile having a U-shaped cross-section central portion, wherein the joints at both ends are asymmetrical in shape, and the cross-sectional shapes are aligned in the same direction so that they can be joined in a straight line. An asymmetric U characterized in that a flat portion is provided in the vicinity of the joint portions at both ends in the same direction as the driving normal, and the joint portion and the flat portion are positioned on the same straight line at the outermost edge of the sheet pile wall. Type steel sheet pile. 6. With respect to the joint portions at both ends, one of the left and right joints is formed inward and the other is outward, and they are engaged with each other at a position not exposed on the inner surface of the outermost edge of the sheet pile wall. Item 5. The asymmetric U-shaped steel sheet pile according to Item 5.