Earth retaining structure

Abstract

To provide earth retaining structure that reduces resistance to ground while suppressing rotation of the earth retaining structure in a circumferential direction.SOLUTION: An earth retaining structure is used as an earth retaining structure in a press-in caisson method, and has a body formed in a cylindrical shape, a cutting edge ring provided at one end of the body, and a guide fin that protrudes from an outer circumference side of the body and prevents the body from rotating in a circumferential direction, the guide fin has a tapered lower end part when viewed from a side surface of the body.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a retaining structure that is submerged underground.

Background Art

[0002] Conventionally, as a pressing method for a retaining structure for constructing a vertical underground structure, the Urban Ring method (registered trademark) is known. In the Urban Ring method, retaining panels are assembled into a ring-shaped structure at the sinking site, and the ring-shaped structure is pressed into the ground by a pressing device. Then, after the ring-shaped structure is pressed into the ground, the inside of the ring-shaped structure is excavated and the soil is removed, and the operation process of adding a new ring-shaped structure on it is repeated to a predetermined depth, thereby constructing an underground structure such as a shaft (for example, see Patent Document 1).

[0003] When the retaining structure is submerged underground, the retaining structure may rotate in the circumferential direction, and the sinking direction of the retaining structure may deviate from the vertical direction. If the sinking of the retaining structure is not performed straight down into the ground and causes inconvenience in construction and use, the retaining structure is pulled out by a predetermined amount upward, and then the sinking is resumed while controlling the posture of the retaining structure while balancing the reaction force applied to the retaining structure. In such a case, a construction space for correcting the posture of the retaining structure is required, which causes problems such as higher labor costs and an extended construction period. Therefore, when the retaining structure is submerged underground, it is required that the retaining structure be submerged straight with high accuracy. For example, in order to suppress the rotation of the retaining structure in the circumferential direction, it is conceivable to provide a protrusion or the like extending in the sinking direction of the retaining structure on the outer peripheral surface.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the protrusions provided on the outer peripheral surface of the earth retaining structure protrude from the outer peripheral surface of the earth retaining structure, and there is ground around the protrusions in the ground. Therefore, the protrusions provided on the outer peripheral surface of the earth retaining structure receive the resistance of the ground vertically when the earth retaining structure is jacked and sunk, and become the resistance to the sinking of the earth retaining structure. For the earth retaining structure used in the jacking method, it is desired to reduce the resistance to the ground when jacking and sinking.

[0006] The present invention solves the above problems, and provides an earth retaining structure that suppresses the circumferential rotation of the earth retaining structure while reducing the resistance to the ground.

Means for Solving the Problems

[0007] The earth retaining structure according to the present invention is an earth retaining structure used as an earth retaining wall in the jacked caisson method, and includes a main body portion formed in a cylindrical shape, a cutting edge ring provided at one end of the main body portion, and a guide fin protruding from the outer peripheral side of the main body portion and suppressing the rotation of the main body portion in the circumferential direction. The guide fin When the main body part is viewed from the radial direction, has a tapered lower end portion and the main body part is formed by a plurality of annular segment rings that are continuously connected in multiple stages along the extending direction of the main body part. The segment ring is formed by arranging a plurality of earth-retaining panels in an annular shape. Each of the plurality of earth-retaining panels has a joint plate used to connect each of the plurality of earth-retaining panels in the circumferential direction. The guide fin is formed by two joint plates at the connected part of two adjacent earth-retaining panels in the circumferential direction of the main body part. and is like this.

Effects of the Invention

[0008] The earth retaining structure of the present invention has a guide fin protruding from the outer peripheral side of the main body portion and suppressing the rotation of the main body portion in the circumferential direction. The guide fin has a tapered lower end portion when viewed from the side of the main body portion. The guide fin having such a configuration can reduce the resistance by converting the compressive failure at the tip, which is the resistance when the guide fin penetrates into the ground, into tensile failure, as compared with a guide fin having no lower end portion of such a configuration. Therefore, the earth retaining structure provided with the guide fin having the lower end portion of such a configuration can achieve both the anti-rotation effect and the effect of reducing the jacking resistance, and suppress the circumferential rotation of the earth retaining structure while reducing the resistance to the ground.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the earth retaining structure according to the embodiment will be described with reference to the drawings and the like. In the following drawings including FIG. 1, the relative dimensional relationships and shapes of the respective constituent members may be different from the actual ones. Further, in the following drawings, those denoted by the same reference numerals are the same or corresponding ones, and this shall be common throughout the entire text of the specification. In addition, for the sake of easy understanding, terms indicating directions (for example, up, down, left, right, front, rear, front and back, etc.) are appropriately used, but their notations are for convenience of explanation and do not limit the arrangement, direction, and orientation of the device, instrument, or component, etc.

[0011] Embodiment. [Earth retaining structure 100] FIG. 1 is a perspective view schematically showing the earth retaining structure 100 according to the embodiment. FIG. 2 is a perspective view schematically showing the inside of the earth retaining structure 100 according to the embodiment. FIG. 2 is a view showing a part of the peripheral wall of the earth retaining structure 100 shown in FIG. 1 cut out for explaining the internal structure of the earth retaining structure 100. The earth retaining structure 100 will be described with reference to FIGS. 1 and 2. Note that the hole axis direction AD shown in FIGS. 1 and 2 represents the axial direction of the earth retaining structure 100, and the circumferential direction CD represents the circumferential direction of the earth retaining structure 100. Further, the radial direction RD represents the radial direction of the earth retaining structure 100, the Y1 side represents the inner peripheral side of the earth retaining structure 100, and the Y2 side represents the outer peripheral side of the earth retaining structure 100.

[0012] The earth retaining structure 100 is a structure used as an earth retaining wall by the jacked caisson method. The earth retaining structure 100 is a structure that covers the excavation surface in the ground in a construction method such as the jacking method. The earth retaining structure 100 is submerged in the ground 200.

[0013] The earth retaining structure 100 is formed in a cylindrical shape and has a hollow portion. The earth retaining structure 100 is arranged in the ground such that the cylindrical hole axis direction AD is in the vertical direction. The earth retaining structure 100 is formed in a circular shape when viewed in the hole axis direction AD and is formed in a cylindrical shape as a whole, but is not limited to a cylindrical shape. As long as the earth retaining structure 100 is formed in a cylindrical shape, for example, when viewed in the hole axis direction AD, it may be formed in other shapes such as an oval shape, a oval coin shape, or a square shape with rounded corners.

[0014] The earth retaining structure 100 includes a main body portion 110 formed in a cylindrical shape, a cutting edge ring 120 provided at one end of the main body portion 110, and a guide fin 130 protruding from the outer peripheral side of the main body portion 110 to prevent the main body portion 110 from rotating in the circumferential direction CD.

[0015] The specific configuration of the earth retaining structure 100 will be further described. The earth retaining structure 100 is formed by stacking a plurality of segment rings 101 vertically. The segment ring 101 is a structure formed in an annular shape and has a length in the hole axis direction AD that is shorter than that of the earth retaining structure 100. The earth retaining structure 100 is constructed by connecting a plurality of segment rings 101 along the extending direction of the earth retaining structure 100, that is, the hole axis direction AD.

[0016] In the segment rings 101 adjacent to each other vertically, the segment ring 101 located in the upper stage and the segment ring 101 located in the lower stage are assembled in a state where the positions of the earth retaining panels 10, which will be described later and constitute the segment ring 101, are shifted in the circumferential direction CD. More specifically, in the segment rings 101 adjacent to each other vertically, the segment ring 101 located in the upper stage and the segment ring 101 located in the lower stage are stacked such that the earth retaining panels 10 are in a staggered arrangement.

[0017] At the lower end of the lowermost segment ring 101 of the earth retaining structure 100, a cutting edge ring 120 is installed. The cutting edge ring 120 is a structure formed in a cylindrical shape similar to the segment ring 101, and is a part that constitutes the cutting edge 120a at the tip of the earth retaining structure 100. The earth retaining structure 100 is sunk into the ground 200 from this cutting edge ring 120.

[0018] [Earth retaining panel 10] The earth retaining panel 10 constitutes a segment ring 101 formed in a cylindrical shape that covers the underground excavation surface by being arranged annularly and connected to each other in the circumferential direction CD. The segment ring 101 is divided into a plurality of earth retaining panels 10 in the circumferential direction CD. The earth retaining panel 10 is formed in an arc shape when viewed in the axial direction AD of the hole axis of the segment ring 101, and is formed in a curved shape. A plurality of earth retaining panels 10 are arranged annularly, and the adjacent earth retaining panels 10 are connected to each other to form the segment ring 101. Note that not all of the earth retaining panels 10 are necessarily formed to have the same size in the circumferential direction CD.

[0019] FIG. 3 is a perspective view showing the earth retaining panel 10 according to the embodiment. As shown in FIG. 3, the earth retaining panel 10 has a skin plate 11, a main girder 12, and a joint plate 13. The earth retaining panel 10 is formed in a concave shape that opens toward the inside of the excavation hole. The skin plate 11, the main girder 12, and the joint plate 13 are each fixed by welding.

[0020] The skin plate 11 is formed in a plate shape having a curved surface. The skin plate 11 is formed to extend in the circumferential direction CD and the axial direction AD of the hole axis. The skin plate 11 is formed in an arc shape in a plan view when viewed in the axial direction AD of the hole axis, and is formed in a rectangular shape in a side view when viewed in the radial direction RD. The skin plate 11 faces the wall surface of the excavation hole in a state where the earth retaining panel 10 is installed in the ground, and constitutes the peripheral wall of the earth retaining structure 100.

[0021] The main girder 12 is formed in a flat plate shape. The main girder 12 is formed so as to extend in the circumferential direction CD and the radial direction RD. The main girder 12 is formed in a plate shape so as to spread horizontally in a state where the earth-retaining panel 10 is installed in the ground. The main girder 12 is formed in an arc shape in a plan view when viewed in the hole axis direction AD, and is formed in an annular sector shape.

[0022] The main girder 12 is provided at the upper and lower ends of the skin plate 11, and forms the upper and lower surfaces of the earth-retaining panel 10. That is, in a state where the earth-retaining panel 10 is installed in the ground, the main girder 12 provided at the upper end of the skin plate 11 forms the ceiling wall of the earth-retaining panel 10, and the main girder 12 provided at the lower end of the skin plate 11 forms the bottom wall of the earth-retaining panel 10.

[0023] The joint plate 13 is formed in a plate shape. Each of the plurality of earth-retaining panels 10 has a joint plate 13 used for connecting each of the plurality of earth-retaining panels 10 in the circumferential direction CD. The joint plate 13 is formed so as to extend in the hole axis direction AD and the radial direction RD. The joint plate 13 is formed so as to spread vertically in a state where the earth-retaining panel 10 is installed in the ground. The joint plate 13 is formed in a square shape when viewed in the circumferential direction CD of the earth-retaining structure 100.

[0024] The joint plate 13 is disposed so as to cover an opening formed by two main girders 12 arranged vertically and the skin plate 11 at both ends in the circumferential direction CD of the earth-retaining panel 10. The joint plate 13 is provided at both ends in the arc direction of the skin plate 11 and forms the left and right side surfaces of the earth-retaining panel 10.

[0025] Of the joint plates 13 that form the left and right side surfaces of the earth retaining panel 10, the joint plate 13a disposed at one end of the earth retaining panel 10 in the circumferential direction CD has a guide fin 130. Note that the configuration of the earth retaining panel 10 is not limited to this configuration, and the joint plate 13a may be provided at both ends in the circumferential direction CD of the earth retaining panel 10. The main body 110 of the earth retaining structure 100 is formed by the portion of the earth retaining panel 10 excluding the guide fin 130. The guide fin 130 of the earth retaining structure 100 is provided on the joint plate 13a of the earth retaining panel 10. The structure of the guide fin 130 will be described later.

[0026] Also, the earth retaining panel 10 is disposed between the upper main girder 12 and the lower main girder 12, and has vertical ribs 14 for maintaining the shape of the earth retaining panel 10 during manufacturing, transportation, and construction. The vertical ribs 14 are constituted by, for example, plate-like members such as steel plates as shown in the figure, or bar-like members such as reinforcing bars (not shown). In the case of the illustrated example, four vertical ribs 14 are arranged at intervals in the circumferential direction CD. Note that the shape and the number of installed vertical ribs 14 are not limited to the illustrated example, and are determined in consideration of, for example, the size and shape of the earth retaining panel 10.

[0027] A plurality of connecting holes 12b for connecting adjacent earth retaining panels 10 stacked vertically in the hole axis direction AD are formed in the main girder 12. As an example, two connecting holes 12b are formed at each interval partitioned by the vertical ribs 14. The adjacent earth retaining panels 10 stacked vertically are connected by butting the main girders 12 and fastening the shaft portions of bolts inserted through the connecting holes 12b with nuts. Note that the number of formed connecting holes 12b is not limited to the illustrated example, and is determined in consideration of, for example, the size and shape of the earth retaining panel 10.

[0028] As shown in Fig. 3, a plurality of connecting holes 13b are formed in the joint plate 13 for connecting the adjacent earth retaining panels 10 arranged in the circumferential direction CD of the excavation hole. The adjacent earth retaining panels 10 on the left and right are connected by butting the joint plates 13 and fastening the shaft portions of the bolts inserted through the connecting holes 13b with nuts. Note that the number of the illustrated connecting holes 13b is an example and is not limited thereto, and is determined in consideration of, for example, the size and shape of the earth retaining panel 10 and the like.

[0029] [Guide fin 130] Fig. 4 is a plan view schematically showing the earth retaining structure 100 according to the embodiment. Fig. 4 shows an example of the earth retaining structure 100 viewed in the hole axis direction AD. As shown in Fig. 4, in the circumferential direction CD of the earth retaining structure 100, a plurality of earth retaining panels 10 are arranged, and the adjacent earth retaining panels 10 are connected to each other. The earth retaining structure 100 shown in Fig. 4 has four earth retaining panels 10 in the circumferential direction CD, but the number of the earth retaining panels 10 in the circumferential direction CD is not limited to four, and may be one or a plurality other than four.

[0030] In the earth retaining structure 100, the main body portion 110 is a portion formed in a cylindrical shape. And in the earth retaining structure 100, the guide fin 130 is a portion protruding outward from the main body portion 110 formed in a cylindrical shape. The guide fin 130 is a portion protruding in the radial direction RD from the outer peripheral wall 110a of the main body portion 110. The main body portion 110 is formed by a plurality of annular segment rings 101 continuously connected in multiple stages along the extending direction of the main body portion 110.

[0031] The guide fin 130 protrudes from the main body portion 110 and serves as a resistance to the ground 200 such as earth and sand when the main body portion 110 rotates in the circumferential direction CD, thereby preventing the main body portion 110 from rotating in the circumferential direction CD in the ground. That is, the guide fin 130 suppresses the horizontal rotation of the earth retaining structure 100. Further, the guide fin 130 suppresses the vertical rotation of the earth retaining structure 100 by preventing the main body portion 110 from rotating in the circumferential direction CD in the ground.

[0032] FIG. 5 is a side view schematically showing a guide fin 130 of the earth retaining structure 100 according to the embodiment. FIG. 5 shows an example of the guide fin 130 in the direction of the white arrow in FIG. 4, that is, when the earth retaining structure 100 is viewed in the radial direction RD. The guide fin 130 is formed in a columnar shape so as to extend in the hole axis direction AD. The guide fin 130 has a fin main body portion 131 and a fin tip portion 132.

[0033] The fin main body portion 131 is a portion that extends in a columnar shape in the guide fin 130. The fin main body portion 131 shown in FIGS. 4 and 5 is formed in a quadrangular columnar shape that extends in the hole axis direction AD. However, the fin main body portion 131 only needs to be columnar and extend in the hole axis direction AD, and may be formed in other shapes. For example, the fin main body portion 131 may be formed in other polygonal columnar shapes such as a triangular columnar shape whose vertical cross section with respect to the hole axis direction AD is triangular, or may be formed in a semi-cylindrical shape whose vertical cross section with respect to the hole axis direction AD is semi-circular.

[0034] The fin tip portion 132 is the lower end portion of the guide fin 130. When the earth retaining structure 100 is viewed from the side, the fin tip portion 132 is formed in a tapered shape from the end on the side where the blade edge ring 120 of the earth retaining structure 100 is not provided in the hole axis direction AD toward the end on the side where the blade edge ring 120 is provided (see FIG. 1). That is, when the guide fin 130 is viewed in the radial direction RD of the earth retaining structure 100, the fin tip portion 132 is formed in a tapered shape from the upper end portion to the lower end portion of the earth retaining structure 100.

[0035] The fin tip portion 132 has an inclined surface 133 facing the circumferential direction CD and the hole axis direction AD. The fin tip portion 132 has two inclined surfaces 133, and the inclined surface 133 formed on one side in the circumferential direction CD and the inclined surface 133 formed on the other side are facing in opposite directions in the circumferential direction CD. Also, both of these inclined surfaces 133 face the side where the blade edge ring 120 is arranged in the hole axis direction AD.

[0036] The guide fin 130 has a fin tip portion 132 having two inclined surfaces 133, and when viewed from the side surface of the main body portion 110 of the earth retaining structure 100, the lower end portion of the guide fin 130 is formed in a tapered shape. In other words, the main body portion 110 of the earth retaining structure 100 is formed in a cylindrical shape, and when the main body portion 110 is viewed from the radial direction RD, the lower end portion of the guide fin 130 is formed in a tapered shape. And the fin tip portion 132, which is the lower end portion of the guide fin 130, is formed in an isosceles triangle shape by the two inclined surfaces 133 when viewed from the side surface of the main body portion 110.

[0037] FIG. 6 is a side view schematically showing another example of the guide fin 130 of the earth retaining structure 100 according to the embodiment. The guide fin 130 shown in FIG. 5 is formed by one joint plate 13a constituting the earth retaining panel 10. The guide fin 130 of the earth retaining structure 100 is not limited to being formed by one joint plate 13a, and as shown in FIG. 6, it may be formed by two joint plates 13a. That is, in the circumferential direction CD, the guide fin 130 of the earth retaining structure 100 may be formed by the two joint plates 13a at the connected portion of the two adjacent earth retaining panels 10.

[0038] FIG. 7 is a perspective view schematically showing another example of the fin tip portion 132 of the earth retaining structure 100 according to the embodiment. The fin tip portion 132 shown in FIGS. 5 to 6 is formed in a tapered shape in the circumferential direction CD. That is, the fin tip portion 132 is formed in a tapered shape when viewed in the radial direction RD. In addition to the above configuration, the fin tip portion 132 may further be formed in a tapered shape in the radial direction RD as shown in FIG. 7. That is, the fin tip portion 132 may be formed in a tapered shape when viewed in the circumferential direction CD.

[0039] When the earth retaining structure 100 is viewed in the circumferential direction CD, the fin tip 132 is formed in a tapered shape from the end on the side where the cutting edge ring 120 of the earth retaining structure 100 is not provided in the hole axis direction AD toward the end on the side where the cutting edge ring 120 is provided (see Fig. 1). That is, when the guide fin 130 is viewed in the circumferential direction CD of the earth retaining structure 100, the fin tip 132 is formed in a tapered shape from the upper end to the lower end of the earth retaining structure 100.

[0040] In addition to the inclined surface 133 facing the circumferential direction CD and the hole axis direction AD, the fin tip 132 has an inclined surface 133a facing the radial direction RD and the hole axis direction AD. Since the fin tip 132, which is the lower end of the guide fin 130, further has the inclined surface 133a in addition to the inclined surface 133, the fin tip 132 is formed in a tapered shape when the guide fin 130 is viewed from the circumferential direction CD of the main body 110.

[0041] Fig. 8 is a perspective view schematically showing another example of the fin main body 131 of the earth retaining structure 100 according to the embodiment. The fin main body 131 shown in Figs. 5 to 6 is formed in a rectangular parallelepiped shape, but the fin main body 131 is not limited to being formed in a rectangular parallelepiped shape. The fin main body 131 may be formed in a tapered shape as shown in Fig. 8, for example, when viewed from the side surface of the main body 110.

[0042] When the earth retaining structure 100 is viewed from the side, the fin main body 131 is formed in a tapered shape from the end on the side where the cutting edge ring 120 of the earth retaining structure 100 is not provided in the hole axis direction AD toward the end on the side where the cutting edge ring 120 is provided (see Fig. 1). That is, when the guide fin 130 is viewed in the radial direction RD of the earth retaining structure 100, the fin main body 131 is formed in a tapered shape from the upper end to the lower end of the earth retaining structure 100.

[0043] The fin body portion 131 has an inclined surface 131a facing the circumferential direction CD and the hole axis direction AD. The fin body portion 131 has two inclined surfaces 131a. The inclined surface 131a formed on one side in the circumferential direction CD and the inclined surface 131a formed on the other side face in opposite directions in the circumferential direction CD. Further, both of these inclined surfaces 131a face the arrangement side of the blade ring 120 with respect to each other in the hole axis direction AD.

[0044] The inclined surface 131a of the fin body portion 131 and the inclined surface 133 of the fin tip portion 132 may be formed flush with each other, or may be formed to be inclined at different angles from each other. By having the inclined surface 131a of the fin body portion 131 and the inclined surface 133 of the fin tip portion 132, the entire guide fin 130 may be formed in a tapered shape that tapers toward the lower end when viewed from the side surface of the main body portion 110.

[0045] [An example of the construction method of the earth retaining structure 100] In the construction method of the earth retaining structure 100 according to the embodiment, first, an excavation hole for constructing the earth retaining structure 100 is formed on the ground. After the excavation hole is formed, the blade ring 120 is installed along the wall surface of the excavation hole. Then, the earth retaining panel 10 is annularly arranged above the blade ring 120, the segment ring 101 is assembled, and a new earth retaining panel 10 is annularly arranged above the assembled segment ring 101 and a new segment ring 101 is assembled. The number of stacked stages of the segment ring 101 is determined according to the construction conditions such as the size and shape of the excavation hole.

[0046] The segment ring 101 is assembled by sequentially arranging the earth retaining panels 10 along the circumferential direction CD of the wall surface of the excavation hole and connecting the adjacent earth retaining panels 10 on the left and right with bolts and nuts. The number of the earth retaining panels 10 constituting the segment ring 101 is determined according to the size and shape of the excavation hole and the like.

[0047] The earth-retaining panels 10 adjacent to each other vertically are connected by bolts and nuts. Note that the earth-retaining panels 10 of the segment rings 101 adjacent to each other vertically are arranged with their positions in the circumferential direction CD shifted so as to be in a staggered arrangement.

[0048] The earth-retaining structure 100 is sunk into the ground 200 from the cutting-edge ring 120. The sinking of the earth-retaining structure 100 is carried out by pressing the earth-retaining structure 100 into the ground 200 not only by the gravity due to its own weight but also by the force applied downward by a hydraulic unit (not shown). In parallel with the pressing of the earth-retaining structure 100 into the ground 200, the inside of the earth-retaining structure 100 is excavated by the bucket of an excavator (not shown). Then, while excavating the ground 200, the earth-retaining panels 10 are assembled to construct the segment ring 101. When the segment ring 101 is sunk, the next segment ring 101 is stacked and connected from above, and pressing and excavation are carried out again, and excavation proceeds to a predetermined depth.

[0049] When the earth-retaining structure 100 is being pressed in, even if the earth-retaining structure 100 tries to rotate in the circumferential direction CD, the guide fin 130 comes into contact with the surrounding ground 200, thereby suppressing the rotation of the earth-retaining structure 100 in the circumferential direction CD. Further, if the earth-retaining structure 100 tries to rotate and displacement occurs in the circumferential direction CD, the guide fin 130 comes into contact with the surrounding ground 200, resulting in an increase in resistance, and such displacement is suppressed. As a result, the sinking of the earth-retaining structure 100 is likely to be carried out straight with respect to the ground 200.

[0050] FIG. 9 is a conceptual diagram showing the relationship between the guide fin 130L without the fin tip portion 132 and the ground 200 when the earth-retaining structure according to the comparative example is being pressed in. FIG. 10 is a conceptual diagram showing the relationship between the guide fin 130 and the ground 200 when the earth-retaining structure 100 according to the embodiment is being pressed in. Using FIGS. 9 and 10, the relationship between the guide fin 130 and the ground 200 when the guide fin 130 is penetrated into the ground 200 will be described.

[0051] Figs. 9(a) and 10(a) show the guide fin 130L and the guide fin 130 before penetration into the ground 200. Figs. 9(b) and 10(b) show the guide fin 130L and the guide fin 130 in the state of being penetrated into the ground 200. Figs. 9(c) and 10(c) show the guide fin 130L and the guide fin 130 in the state of being penetrated deeper into the ground 200 than in (b).

[0052] In the soil with reduced strength and loosened state, a guide fin 130L with a flat bottom surface as shown in Fig. 9 is used. However, in recent years, when using soil retaining structures at great depths or when using soil retaining structures in hard ground where the maximum N value is greater than 50, etc., the penetration resistance of the guide fin 130L has become a situation that cannot be ignored in such cases.

[0053] In the case of the guide fin 130L with a flat bottom surface shown in Fig. 9, as shown in Figs. 9(b) and 9(c), a compressive force CS that compresses the ground 200 in the penetration direction of the guide fin 130L is applied to the ground 200 by the bottom surface of the guide fin 130L. Therefore, the ground 200 is compressed and damaged by the bottom surface of the guide fin 130L. When the bottom surface of the guide fin 130 of the soil retaining structure 100 is a flat surface without a tapered shape, the guide fin 130 vertically receives the resistance of the ground 200 when the soil retaining structure 100 sinks, which becomes the resistance to sinking.

[0054] In the case of the guide fin 130 having the fin tip portion 132 shown in Fig. 10, as shown in Figs. 10(b) and 10(c), a tensile force TS that compresses the ground 200 in a direction perpendicular to the penetration direction of the guide fin 130 is applied to the ground 200 by the inclined surface 133 of the fin tip portion 132. Therefore, the ground 200 is tensilely damaged by the fin tip portion 132 of the guide fin 130.

[0055] The properties of soil are such that the compressive resistance due to compressive failure is greater than the tensile resistance due to tensile failure. For example, it can be considered that the magnitude of tensile failure is about 0.1 times that of compressive failure. That is, the characteristics of soil are such that the compressive strength is greater than the tensile strength.

[0056] The guide fin 130 having the fin tip portion 132 can suppress the resistance received from the ground 200 to about 10% of the compressive resistance by converting the compressive failure at the tip, which is the resistance when the guide fin 130 is penetrated into the ground 200, into tensile failure. Therefore, the guide fin 130 having the fin tip portion 132 can reduce the resistance as compared with the guide fin 130L without the fin tip portion 132 by converting the compressive failure at the tip, which is the resistance when the guide fin is penetrated into the ground 200, into tensile failure.

[0057] In addition, the earth retaining structure 100 provided with a plurality of guide fins 130 having the fin tip portions 132 can greatly suppress the resistance from the ground 200 as compared with the earth retaining structure provided with a plurality of guide fins 130L without the fin tip portions 132. The earth retaining structure 100 provided with a plurality of guide fins 130 having the fin tip portions 132 can achieve both the anti-rotation effect and the effect of reducing the press-in resistance.

[0058] It should be noted that the adhesive force AS, which is the resistance acting on the side surface of the guide fin 130L shown in FIG. 9 and acting after the failure of the ground 200, and the adhesive force AS, which is the resistance acting on the side surface of the fin main body portion 131 of the guide fin 130 in FIG. 10, are considered to be approximately the same magnitude.

[0059] FIG. 11 is a conceptual diagram showing the relationship between the guide fin 130 and the blade ring 120 of the earth retaining structure 100 according to the embodiment. Note that FIG. 11 illustrates a partial omission of the structure of the main body 110 in the hole axis direction AD in order to explain the relationship between the guide fin 130 and the friction cut portion 121. As shown in FIG. 11, the blade ring 120 is provided with a friction cut portion 121 that protrudes outward from the outer peripheral surface 120b of the blade ring 120. The friction cut portion 121 is used to form a gap between the outer peripheral surface of the main body 110 and the surrounding ground 200 due to the sinking of the blade ring 120, and to reduce the circumferential surface friction of the main body 110.

[0060] As shown in FIG. 11, the guide fin 130 is formed such that the height GH of the guide fin 130 is equal to the height FH of the friction cut portion 121 plus the protruding height PH. The protruding height PH is, for example, a dimension such as 5 mm or more and 25 mm or less. That is, the guide fin 130 is formed to protrude 5 mm or more and 25 mm or less outward in the radial direction RD of the main body 110 from the tip position in the protruding direction at the lowermost end position of the friction cut portion 121. Note that the dimension of the protruding height PH, that is, the protruding amount of the guide fin 130 protruding from the tip position in the protruding direction of the friction cut portion 121 in the radial direction RD of the main body 110 is not limited to a length of 5 mm or more and 25 mm or less. These dimensions and protruding amounts are determined in consideration of, for example, the size and shape of the earth retaining structure 100, or the state of the ground 200.

[0061] The height GH of the guide fin 130 is the distance between the central portion C of the main body portion 110 and the tip portion 130a in the protruding direction of the guide fin 130 in a direction perpendicular to the hole axis direction AD. Further, the height FH of the friction cut portion 121 is the distance between the central portion C of the main body portion 110 and the tip portion 121a in the protruding direction at the lowermost end position of the friction cut portion 121 in a direction perpendicular to the hole axis direction AD. The protruding height PH is the distance between the position of the tip portion 130a of the guide fin 130 and the tip portion 121a of the friction cut portion 121 in a direction perpendicular to the hole axis direction AD.

[0062] FIG. 12 is a conceptual diagram showing another example of the friction cut portion 121 of the earth retaining structure 100 according to the embodiment. The friction cut portion 121 is not limited to the shape formed in a rectangle as shown in FIG. 11 in a cross section along the hole axis direction AD. The friction cut portion 121 may be formed in a quadrangular shape with different side lengths as shown in FIG. 12(A), for example, in a cross section along the hole axis direction AD, or may be formed in a shape of another polygon other than a quadrilateral. Alternatively, the friction cut portion 121 may be formed in a stepped shape having a plurality of stages in the radial direction RD as shown in FIG. 12(B). Even for the friction cut portion 121 having the shape shown in FIG. 12, the tip portion 121a of the friction cut portion 121 is the tip position in the protruding direction at the lowermost end position of the friction cut portion 121 in the radial direction RD of the main body portion 110.

[0063] Note that in a direction perpendicular to the hole axis direction AD, the distance between the outer peripheral surface 120b of the cutting edge ring 120 and the tip 121a in the protruding direction of the friction cut portion 121 is defined as the cutting width CH. In this case, in a direction perpendicular to the hole axis direction AD, the guide fin 130 may be formed to such a size that the position of the tip 130a in the protruding direction of the guide fin 130 exists at a position obtained by adding the protruding height PH to the cutting width CH. The region forming the cutting width CH is a region where earth and sand or the like are removed by the friction cut portion 121 when the earth retaining structure 100 is press-fitted, and is a portion where a gap is formed between the cutting edge ring 120 or the main body portion 110 and the ground 200.

[0064] [Function and Effect of Earth Retaining Structure 100] The earth retaining structure 100 protrudes from the outer peripheral side of the main body portion 110 and has guide fins 130 that prevent the main body portion 110 from rotating in the circumferential direction CD. The lower end portion of the guide fin 130 is formed in a tapered shape when viewed from the side surface of the main body portion 110. The guide fin 130 having such a configuration can reduce the resistance as compared with a guide fin having no lower end portion of such a configuration by converting the compressive failure at the tip, which is the resistance when the guide fin 130 penetrates into the ground 200, into tensile failure. Therefore, the earth retaining structure 100 provided with the guide fin 130 having the lower end portion of such a configuration can achieve both the anti-rotation effect and the effect of reducing the press-fitting resistance, and while suppressing the rotation of the earth retaining structure 100 in the circumferential direction CD, the resistance with the ground 200 is alleviated.

[0065] In addition, when viewed from the side of the main body portion 110, the lower end portion of the guide fin 130 is formed in a tapered shape. That is, the guide fin 130 has an inclined surface 133 facing the circumferential direction CD. For example, if the lower end portion of the guide fin has a radial inclined surface, excessive pressure may be applied to the main body portion toward the center of the main body portion depending on the ground, and compression failure of the ground 200 may occur. However, the earth retaining structure 100 can suppress the pressure toward the center of the main body portion 110 by having the inclined surface 133 in the circumferential direction CD at the lower end portion of the guide fin 130, and can convert the compression failure of the ground 200 into tensile failure, thereby relaxing the resistance against the ground 200.

[0066] In addition, the main body portion 110 is formed in a cylindrical shape, and when the guide fin 130 is viewed from the radial direction RD of the main body portion 110, the lower end portion is formed in a tapered shape. Compared with the main body portion 110 whose shape of the vertical cross section with respect to the hole axis direction AD of the main body portion 110 is an oval shape, an oval shape, or a square shape, the cylindrical main body portion 110 is easy to rotate in the circumferential direction CD. However, the earth retaining structure 100 has the guide fin 130 whose lower end portion is formed in a tapered shape when viewed from the radial direction RD of the main body portion 110. Therefore, the earth retaining structure 100 provided with the guide fin 130 having the lower end portion of the said structure can achieve both the anti-rotation effect and the effect of reducing the press-fitting resistance even if the main body portion 110 is cylindrical.

[0067] In addition, the lower end portion of the guide fin 130 is formed in an isosceles triangle shape when viewed from the side of the main body portion 110. That is, the guide fin 130 has an inclined surface 133 facing the circumferential direction CD. The earth retaining structure 100 can convert the compression failure of the ground 200 into tensile failure by having the inclined surface 133 facing the circumferential direction CD at the lower end portion of the guide fin 130, thereby relaxing the resistance against the ground 200. Therefore, the earth retaining structure 100 provided with the guide fin 130 having the lower end portion of the said structure can achieve both the anti-rotation effect and the effect of reducing the press-fitting resistance, and while suppressing the rotation of the earth retaining structure 100 in the circumferential direction CD, the resistance against the ground 200 is relaxed.

[0068] Also, the fin tip portion 132, which is the lower end portion of the guide fin 130, may be formed in a tapered shape when the guide fin 130 is viewed from the circumferential direction CD of the main body portion 110. That is, the guide fin 130 further has an inclined surface 133a facing the radial direction RD. By further having the inclined surface 133a facing the radial direction RD at the lower end portion of the guide fin 130, the earth retaining structure 100 can convert the compressive failure of the ground 200 into tensile failure even in the radial direction RD, so the resistance to the ground 200 is further alleviated. Therefore, the earth retaining structure 100 provided with the guide fin 130 having the lower end portion of the said structure can further achieve both the anti-rotation effect and the effect of reducing the press-fitting resistance.

[0069] Also, the guide fin 130 may be formed in an overall tapered shape when viewed from the side of the main body portion 110. The guide fin 130 having this configuration can reduce the resistance compared to a guide fin not having this configuration by converting the compressive failure at the tip, which is the resistance when the guide fin 130 is penetrated into the ground 200, into tensile failure throughout the guide fin 130. Therefore, the earth retaining structure 100 provided with the guide fin 130 having this configuration can achieve both the anti-rotation effect and the effect of reducing the press-fitting resistance, suppressing the rotation of the earth retaining structure 100 in the circumferential direction CD while alleviating the resistance to the ground 200.

[0070] The guide fin 130 is provided on the joint plate 13 of the earth retaining panel 10. Therefore, the guide fin 130 constitutes a part of the segment ring 101, and the strength of the guide fin 130 can be ensured as compared with the case where the guide fin 130 is attached after the creation of the segment ring 101. Also, the guide fin 130 can be provided when the earth retaining panel 10 is created, and the manufacturing process can be simplified as compared with the case where the guide fin 130 is provided after the creation of the segment ring 101.

[0071] In addition, when the earth retaining structure 100 is pressed into the ground, above the friction cut portion 121 is an area where earth and sand are removed by the friction cut portion 121, and it is a portion where a gap is formed between the cutting edge ring 120 or the main body portion 110 and the ground 200. Therefore, when the cutting edge ring 120 has the friction cut portion 121, in order for the guide fin 130 to serve as a rotation stopper against the ground 200, it must protrude outside the gap by the friction cut portion 121.

[0072] Since the guide fin 130 is formed to protrude outward from the tip position in the protruding direction of the friction cut portion 121 in the radial direction RD of the main body portion 110, the guide fin 130 can serve as a rotation stopper against the ground 200. Also, when the guide fin 130 protrudes too far outside the friction cut portion 121, the guide fin 130 becomes a resistance against the ground 200, making it difficult to press the earth retaining structure 100 into the ground 200. The guide fin 130 is formed to protrude outward by a length of 5 mm or more and 25 mm or less from the tip position in the protruding direction at the lowermost end position of the friction cut portion 121 in the radial direction RD of the main body portion 110. Therefore, the guide fin 130 can suppress the resistance against the ground 200 while serving as a rotation stopper for the earth retaining structure 100.

[0073] The configurations shown in the above embodiments are examples, and it is possible to combine them with other known technologies, and it is also possible to omit or change a part of the configuration without departing from the gist.

Explanation of Reference Numerals

[0074] 10 Earth retaining panel, 11 Skin plate, 12 Main girder, 12b Connecting hole, 13 Joint plate, 13a Joint plate, 13b Connecting hole, 14 Vertical rib, 100 Earth retaining structure, 101 Segment ring, 110 Main body part, 110a Outer peripheral wall, 120 Cutting edge ring, 120a Cutting edge, 120b Outer peripheral surface, 121 Friction cut part, 121a Tip part, 130 Guide fin, 130L Guide fin, 130a Tip part, 131 Fin main body part, 131a Inclined surface, 132 Fin tip part, 133 Inclined surface, 133a Inclined surface, 200 Ground, AD Axial direction of hole, AS Adhesion, C Central part, CD Circumferential direction, CH Cutting width, CS Compressive force, FH Height, GH Height, PH Projection height, RD Radial direction, TS Tensile force.

Claims

1. An earth retaining structure used as an earth retaining wall in the jacked caisson method, comprising a main body formed in a cylindrical shape, a cutting edge ring provided at one end of the main body, and guide fins protruding from the outer peripheral side of the main body to prevent the main body from rotating in the circumferential direction, wherein the guide fins have a lower end portion formed in a tapered shape when the main body is viewed from the radial direction, the main body is formed by a plurality of annular segment rings connected continuously in a plurality of stages along the extending direction of the main body, the segment rings are formed by arranging a plurality of earth retaining panels in an annular shape, each of the plurality of earth retaining panels has a joint plate used for connecting the plurality of earth retaining panels in the circumferential direction, the guide fins are earth retaining structures formed by the two joint plates at the connected portion of two adjacent earth retaining panels in the circumferential direction of the main body.

2. The lower end portion is formed in an isosceles triangle shape when the main body is viewed from the radial direction. The earth retaining structure according to claim 1.

3. The lower end portion is further formed in a tapered shape when the guide fin is viewed from the circumferential direction of the main body. The earth retaining structure according to claim 1 or 2.

4. The guide fins are formed in an overall tapered shape when the main body is viewed from the radial direction. The earth retaining structure according to any one of claims 1 to 3.

5. The cutting edge ring has a friction cut portion that protrudes outward from the outer peripheral surface of the cutting edge ring to form a gap between the outer peripheral surface of the main body and the surrounding ground due to the sinking of the cutting edge ring, and is used to reduce the circumferential surface friction of the main body, the guide fins are formed to protrude outward by a length of 5 mm or more and 25 mm or less from the tip position in the protruding direction at the lowermost end position of the friction cut portion in the radial direction of the main body. The earth retaining structure according to any one of claims 1 to 4.

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