Earth retaining structures

Abstract

To provide an earth retaining structure that can increase rigidity without placing reinforcement rings and can improve workability by omitting placing of the reinforcement rings.SOLUTION: An earth retaining structure is constructed by stacking an annular structure in plural stages along a hole axis direction into a drilling hole formed by drilling a ground surface. Each structure has a configuration that is formed to annularly place plural earth retaining panels with the same section modulus. A section modulus of an earth retaining panel of a structure of each stage is same as or different from a section modulus of an earth retaining panel of a structure of another stage. The earth retaining structure includes a structure where a structure constituted with an earth retaining panel of a section modulus larger than that of an earth retaining panel of the structure is placed between structures constituted with an earth retaining panel of a small section modulus in a hole axis direction of the drilling hole.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an earth retaining structure constructed using earth retaining panels. [Background technology]

[0002] Conventionally, there has been known an earth retaining structure constructed by assembling earth retaining panels made of corrugated steel plates in a borehole formed by excavating the ground, as disclosed in, for example, Patent Document 1. The earth retaining structure is constructed by stacking structures formed by arranging a plurality of corrugated steel plates in an annular manner along the wall surface of the borehole in the axial direction of the hole.

[0003] As the depth of an excavation hole increases, the earth pressure from the ground increases, and corrugated steel plates alone may not provide sufficient rigidity. In addition, regardless of the depth, the earth pressure may be large depending on the soil conditions. Furthermore, as the depth in the direction of the hole axis increases, the weight of the structure placed above acts on the structure placed below. For this reason, in soil retaining structures, in areas where rigidity is insufficient, H-shaped steel called reinforcing rings are sandwiched between adjacent corrugated steel plates above and below to increase rigidity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-066845 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the construction of the reinforcing rings is complicated and time-consuming, which lengthens the construction period and increases the construction costs, so there is a demand for a structure that does not require the reinforcing rings.

[0006] The present invention is intended to solve the above-mentioned problems, and aims to provide a retaining structure that can increase rigidity without installing reinforcing rings, and can improve workability by omitting the installation of reinforcing rings. [Means for solving the problem]

[0007] Books The earth-retaining structure of the invention is constructed by stacking annular structures with the same inner diameter in a plurality of stages along the hole axis direction in a borehole formed by excavating the ground, and each of the structures is formed by arranging a plurality of earth-retaining panels made of the same section modulus in a ring shape, and the section modulus of the earth-retaining panels of the structures of each stage is the same as or different from the section modulus of the earth-retaining panels of the structures of the other stages, and the earth-retaining panels have a first earth-retaining panel and a second earth-retaining panel having a larger section modulus than the first earth-retaining panel, and in the hole axis direction of the borehole, the second earth-retaining panel having a larger section modulus than the first earth-retaining panel of the structure is arranged between the structures made of the first earth-retaining panels having a smaller section modulus. The first earth-retaining panel is a corrugated steel plate arranged on the wall surface of the borehole, the first earth-retaining panel having an arc-shaped circumferential flange portion provided along the upper and lower edges and an axial flange portion provided along both edges in the arc direction of the circumferential flange portion, the second earth-retaining panel having a rectangular skin plate facing the wall surface of the borehole, main girders provided at the upper and lower ends of the skin plate to form the upper and lower surfaces, and joint plates provided at both left and right ends of the skin plate to form the left and right side surfaces, the outer diameter side end of the structure formed by the first earth-retaining panel is located on the inner diameter side of the outer diameter side end of the structure formed by the second earth-retaining panel, The inner end face of the second earth retaining panel and the inner end face of the first earth retaining panel are aligned, and as the depth of the excavation hole increases, the number of structures made up of the second earth retaining panels increases. This is what is being done. Effect of the Invention

[0008] The present invention includes a structure in which a structure made of earth retaining panels with a smaller section modulus is placed between structures made of earth retaining panels with a larger section modulus than the earth retaining panels of the structure. In other words, by placing a structure made of earth retaining panels with a large section modulus and high rigidity in a borehole or a deep portion of the borehole where strong earth pressure acts, the rigidity of the entire structure can be increased. Therefore, the installation of reinforcing rings can be omitted, which shortens the construction period and reduces construction costs, and improves workability. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a front view showing a schematic diagram of the retaining structure according to the first embodiment. [Diagram 2] 1 is an oblique view showing an example of a first earth retaining panel that constitutes the earth retaining structure of embodiment 1. FIG. [Diagram 3] A vertical cross-sectional view of the first retaining panel shown in Figure 2. [Figure 4] 2 is an oblique view showing an example of a second earth retaining panel that constitutes the earth retaining structure of embodiment 1. FIG. [Diagram 5] A cross-sectional plan view of the second retaining panel shown in Figure 4. [Figure 6] 5(A) is a front view of the second retaining panel shown in FIG. 4, and (B) is a left side view of the second retaining panel. [Figure 7] 1 is an explanatory diagram showing the relationship between the connecting holes of the first soil retaining panel and the connecting holes of the second soil retaining panel of the retaining structure of embodiment 1. FIG. [Figure 8] FIG. 2 is an explanatory diagram showing a schematic example of a construction method for the earth retaining structure according to the first embodiment. [Figure 9] FIG. 11 is a front view showing a schematic diagram of an earth retaining structure according to embodiment 2. [Figure 10] An oblique view showing an example of a first earth retaining panel that constitutes the earth retaining structure of embodiment 2. [Figure 11] A vertical cross-sectional view of the first retaining panel shown in Figure 10. [Figure 12]13 is an explanatory diagram showing the relationship between the connecting holes of the first soil retaining panel and the connecting holes of the second soil retaining panel of the retaining structure of embodiment 2. FIG. [Figure 13] FIG. 11 is a front view showing a schematic diagram of an earth retaining structure according to embodiment 3. [Figure 14] FIG. 11 is a front view showing a schematic diagram of an earth retaining structure according to embodiment 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will be omitted or simplified as appropriate. In addition, the shape, size, arrangement, etc. of the configurations shown in each drawing may be changed as appropriate within the scope of the present invention.

[0011] Embodiment 1 Fig. 1 is a front view showing a schematic diagram of an earth retaining structure according to the first embodiment. The earth retaining structure 100 is constructed when constructing a civil engineering structure such as a shaft for constructing the foundation of an architectural structure or a drainage well constructed underground. As shown in Fig. 1, the earth retaining structure 100 is constructed by stacking annular structures (101, 102) in a vertical borehole 201 formed by excavating the ground 200 in multiple stages (12 stages in Fig. 1 as an example) along the hole axis direction X.

[0012] Each of the structures (101, 102) constituting the earth-retaining structure 100 is formed by arranging a plurality of earth-retaining panels (1, 2) having the same section modulus in a ring shape. The earth-retaining panels (1, 2) of each stage of the structures (101, 102) have a section modulus that is the same as or different from that of the earth-retaining panels (1, 2) of the other structures (101, 102).

[0013] As the depth of the borehole 201 increases, the retaining structure 100 may become insufficient in rigidity due to the increased earth pressure from the natural ground. In addition, regardless of the depth, the earth pressure may be large due to soil conditions, etc. Furthermore, as the depth in the hole axis direction X increases, the weight of the structures (101, 102) arranged above acts on the structures (101, 102) arranged below.

[0014] For this reason, in conventional earth retaining structures, in deep places, H-shaped steel, called a reinforcing ring, is sandwiched between adjacent structures on the top and bottom to increase rigidity. However, the construction of the reinforcing ring is complicated and time-consuming, which causes problems of longer construction time and higher construction costs. For example, the reinforcing ring protrudes from the outer diameter side of the earth retaining structure toward the wall surface of the borehole, so the borehole must be made larger accordingly, and over-drilling is required. In addition, when backfill grouting material is filled between the outer surface of the earth retaining structure and the wall surface of the borehole, the backfill grouting material may not be sufficiently filled inside the H-shaped steel. In addition, when multiple H-shaped steels are arranged along the circumferential direction of the borehole 201 and adjacent H-shaped steels are connected to the left and right with flange joints, there are connection points that are out of reach of the worker. Therefore, in this assembly work method, the work is performed in a state where it is difficult to visually check, making assembly difficult, and there are concerns about safety confirmation. In other words, there is a demand for the construction of an earth retaining structure in which the reinforcing ring can be omitted.

[0015] Therefore, in the earth retaining structure 100 according to the first embodiment, in the hole axis direction X of the excavation hole 201, between the structures 101 composed of the earth retaining panels 1 having a small section modulus, structures 102 composed of the earth retaining panels 2 having a larger section modulus than the earth retaining panels 1 of the structures 101 are arranged, thereby increasing the rigidity of the entire structure. For example, in the earth retaining structure 100 shown in FIG. 1, the first, third to fifth, seventh, eighth, and tenth stages out of the 12 stages are structures 101 composed of the earth retaining panels 1, and the second, sixth, ninth, eleventh, and twelfth stages are structures 102 composed of the earth retaining panels 2. The height in the hole axis direction X of the structures (101, 102) of each stage is, for example, about 50 cm. The earth retaining structure 100 is assembled by shifting the positions of the earth retaining panels (1, 2) of the structures (101, 102) adjacent to each other in the circumferential direction so that the earth retaining panels (1, 2) are arranged in a staggered pattern. Moreover, as an example, the retaining structure 100 has a circular shape when viewed from above.

[0016] The number and arrangement of the structures (101, 102) of the retaining structure 100 are not limited to the illustrated configuration, and may be modified as appropriate to suit the construction conditions. The number of retaining panels (1, 2) in each structure (101, 102) may also be modified as appropriate to suit the construction conditions.

[0017] FIG. 2 is a perspective view showing an example of a first earth retaining panel constituting the earth retaining structure of embodiment 1. FIG. 3 is a vertical cross-sectional view of the first earth retaining panel shown in FIG. 2. FIG. 4 is a perspective view showing an example of a second earth retaining panel constituting the earth retaining structure of embodiment 1. FIG. 5 is a plan cross-sectional view of the second earth retaining panel shown in FIG. 4. FIG. 6(A) is a front view of the second earth retaining panel shown in FIG. 4, and FIG. 6(B) is a left side view of the second earth retaining panel. FIG. 7 is an explanatory view of the earth retaining structure of embodiment 1, showing the relationship between the connecting holes of the first earth retaining panel and the connecting holes of the second earth retaining panel.

[0018] The earth retaining panels (1, 2) have a first earth retaining panel 1 shown in Figs. 2 and 3, and a second earth retaining panel 2 having a larger section modulus than the first earth retaining panel 1 as shown in Figs.

[0019] The first retaining panel 1 is composed of a corrugated steel plate made of a liner plate 1A. The liner plate 1A has a configuration in which the corrugated cross section is formed in a sine curve shape. The liner plate 1A is formed in an arc shape in a plan view. The liner plate 1A has a thickness of, for example, about 2.7 mm to 7 mm. As shown in Figs. 2 and 3, the liner plate 1A is provided with an arc-shaped circumferential flange portion 10 provided along the upper and lower edges, and an axial flange portion 11 provided along both ends in the arc direction. The circumferential flange portion 10 is formed by bending so as to protrude from the upper and lower edges of the liner plate 1A toward the inside of the drilling hole 201. The axial flange portion 11 is formed by welding a plate to both ends in the arc direction of the liner plate 1A.

[0020] The circumferential flange portion 10 has a plurality of connecting holes 10a formed along the arc direction for connecting adjacent first retaining panels 1 stacked in the hole axis direction X, or connecting the first retaining panel 1 and the second retaining panel 2. The adjacent first retaining panels 1 are connected by butting the circumferential flange portions 10 together and fastening the shafts of bolts inserted into the connecting holes 10a with nuts, for example. The means for connecting the circumferential flange portions 10 of adjacent first retaining panels 1 may be, for example, a connector such as a clip. The number of connecting holes 10a shown in the figure is merely an example and is not limited to this.

[0021] The axial flange portion 11 has a plurality of connecting holes 11a formed in the vertical direction for connecting adjacent first retaining panels 1 arranged in the circumferential direction of the excavation hole 201. Adjacent first retaining panels 1 are connected by butting the axial flange portions 11 together and fastening the shanks of bolts inserted into the connecting holes 11a with nuts. The means for connecting the axial flange portions 11 of adjacent first retaining panels 1 may be, for example, a connector such as a clip. The number of connecting holes 11a shown in the figure is merely an example and is not limited to this.

[0022] The second retaining panel 2 shown in Figs. 4 to 6 is made of steel and is formed in an arc shape in plan view. The second retaining panel 2 has an arc-shaped skin plate 20 facing the wall surface of the borehole 201, an arc-shaped main girder 21 provided at the upper and lower ends of the skin plate 20 to form the upper and lower surfaces, and joint plates 22 provided at both ends of the skin plate 20 in the arc direction to form the left and right side surfaces. The second retaining panel 2 is formed in a concave shape that opens toward the inside of the borehole 201. The skin plate 20, the main girder 21, and the joint plate 22 are fixed by welding. The girder height of the main girder 21 varies depending on the soil quality and depth of the borehole 201, and is, for example, about 150 mm to 400 mm. The cross-sectional rigidity of the second retaining panel 2 can be set by adjusting the plate thickness and girder height of the main girder 21.

[0023] The second earth retaining panel 2 has a shape retention member 23 that is disposed between the upper main girder 21 and the lower main girder 21 and that retains the shape of the second earth retaining panel 2 during manufacture, transportation, and construction. The shape retention member 23 is composed of, for example, a plate-like member made of a steel plate or the like as shown in the figure, or a rod-like member made of a reinforcing bar or the like not shown in the figure. In the illustrated example, four shape retention members 23 are disposed at intervals in the arc direction. Note that the shape and number of the shape retention members 23 are not limited to the illustrated example, and are determined in consideration of, for example, the size and shape of the second earth retaining panel 2, etc.

[0024] The main girder 21 has a plurality of connecting holes 21a for connecting the second retaining panels 2 stacked vertically in the hole axis direction X, or the second retaining panels 2 and the first retaining panels 1. The second retaining panels 2 adjacent to each other vertically are connected by butting the main girders 21 together and fastening the shanks of the bolts inserted into the connecting holes 21a with nuts. The second retaining panels 2 and the first retaining panels 1 adjacent to each other vertically are connected by butting the main girders 21 together with the circumferential flange portions 10 and fastening the shanks of the bolts inserted into the connecting holes 21a and 10a with nuts. The number of connecting holes 21a shown in the figure is an example and is not limited to this.

[0025] Here, the connection hole 10a formed in the first soil retaining panel 1 is the first connection hole, and the connection hole 21a formed in the second soil retaining panel 2 is the second connection hole. For example, as shown in FIG. 7, the first connection hole 10a and the second connection hole 21a are formed at the same position B from the end A on the inner diameter side of the soil retaining structure 100 toward the outer diameter side. In other words, the first connection hole 10a and the second connection hole 21a are formed at equal distances from the end A in the radial direction of the soil retaining structure 100. With this configuration, the end face on the inner diameter side of the second soil retaining panel 2 and the end face on the inner diameter side of the first soil retaining panel 1 can be aligned, so that the effective diameter of the soil retaining structure 100 can be increased. In addition, the end face on the inner diameter side of the second soil retaining panel 2 does not protrude further toward the inner diameter side of the soil retaining structure 100 than the end face on the inner diameter side of the first soil retaining panel 1, so that the internal space is wider and the working space of the worker can be secured. Other effects include making it easier to set up a work ladder during excavation, allowing the inner diameter to be larger for deep foundation piles, making it easier to set up steps for a drainage well, and making it easier to set up supports. Note that the "same position" from the end A on the inner diameter side of the retaining structure 100 does not have to be the exact same position, and the first retaining panel 1 or the second retaining panel 2 may be slightly offset toward the wall surface of the excavation hole 201. Also, although not shown in the figures, the position of the outer surface of the first retaining panel 1 and the position of the outer surface of the second retaining panel 2 may be aligned.

[0026] As shown in Figs. 4 and 5, the upper and lower main girders 21 have a plurality of drilling holes 21b formed at intervals in the arc direction for inserting a tool to drill (pry). Pruning means, for example, inserting an object into a gap and twisting. The tool is, for example, a rod-shaped member such as a shim rod. The drilling holes 21b are provided for the purpose of aligning the positions of the connecting holes 21a of the second retaining panels 2 adjacent to each other vertically, or the positions of the connecting holes 21a of the second retaining panels 2 and the connecting holes 10a of the first retaining panels 1. The drilling holes 21b may be provided in only one of the upper and lower main girders 21, or may be omitted in both. The positions, sizes, and numbers of the drilling holes 21b are not limited to those shown in the drawings, and may be changed as appropriate.

[0027] The joint plate 22 is formed with a plurality of connecting holes 22a for connecting adjacent second retaining panels 2 arranged in the circumferential direction of the excavation hole 201. Adjacent second retaining panels 2 are connected by butting the joint plates 22 together and fastening the shafts of the bolts inserted into the connecting holes 22a with nuts. The number of connecting holes 22a shown in the figure is an example and is not limited to this.

[0028] As shown in Figs. 4 and 6, the left and right joint plates 22 are provided with drilling holes 22b for inserting a tool to drill holes. The tool is, for example, a rod-shaped member such as a sino rod. The drilling holes 22b are provided for the purpose of aligning the positions of the connecting holes 22a of the second retaining panels 2 adjacent to each other on the left and right. The drilling holes 22b may be used to align the positions of the connecting holes 21a of the second retaining panels 2 adjacent to each other on the top and bottom, or the connecting holes 21a of the second retaining panels 2 and the connecting holes 10a of the first retaining panels 1. The drilling holes 22b may be provided in only one of the left and right joint plates 22, or both may be omitted. The positions, sizes, and numbers of the drilling holes 22b are not limited to those shown in the drawings, and may be changed as appropriate.

[0029] Next, an example of a construction method for the above-mentioned earth retaining structure 100 will be described with reference to Fig. 8. Fig. 8 is an explanatory diagram that shows a schematic diagram of an example of a construction method for the earth retaining structure according to the first embodiment.

[0030] In the retaining structure 100 according to the first embodiment, first, as shown in FIG. 8(A), a borehole 201 for constructing the retaining structure 100 is formed in the ground 200. The borehole 201 is formed with an outer diameter, for example, about 20 cm larger than the outer diameter of the retaining structure 100. The depth of the borehole 201 is, for example, about 0.5 m to 1.5 m. Then, the first retaining panel 1 is arranged in a ring shape along the wall surface of the borehole 201 to assemble the structure 101, and the second retaining panel 2 is arranged in a ring shape to assemble the structure 102. In the illustrated example, first, three stages of structures (101, 102) are constructed. Note that the number of stages of structures (101, 102) to be constructed first is not limited to three stages, and the number of stages is determined according to the construction situation, such as the size and shape of the borehole 201.

[0031] The structure 101 is assembled by arranging the first earth retaining panels 1 in order along the circumferential direction of the wall surface of the borehole 201 and connecting adjacent first earth retaining panels 1 on the left and right with bolts and nuts. The number of first earth retaining panels 1 constituting the structure 101 is determined according to the size and shape of the borehole 201, etc. The structure 102 is assembled by arranging the second earth retaining panels 2 in order along the circumferential direction of the wall surface of the borehole 201 and connecting adjacent second earth retaining panels 2 on the left and right with bolts and nuts. The number of second earth retaining panels 2 constituting the structure 102 is also determined according to the size and shape of the borehole 201, etc.

[0032] The first and second earth retaining panels 1 and 2, which are adjacent to each other vertically, are connected with bolts and nuts. The earth retaining panels (1, 2) of the vertically adjacent structures (101, 102) are staggered in the circumferential direction so as to form a staggered arrangement.

[0033] Next, after constructing three tiers of structures (101, 102), the structure 101 located at the top tier is fixed to the ground 200 with a lattice 300, as shown in Fig. 8(B), and then the excavated holes 201 on the outside of the structures (101, 102) are backfilled with excavated soil. Note that the means for fixing the structure 101 located at the top tier to the ground 200 is not limited to the lattice 300, and concrete, for example, may be used.

[0034] Then, as shown in FIG. 8(C), the first and second earth retaining panels 1 and 2 are assembled to construct the structures 101 and 102 while excavating the ground, and excavation is continued to a predetermined depth. After the structure 101 located at the top is fixed with the lattice 300, the first or second earth retaining panel 1 or 2 is placed at the bottom end of the structure 101 at the bottom along the circumferential direction of the wall surface of the excavation hole 201, and the first or second earth retaining panel 1 or 2 is connected to the structure 101 at the bottom with bolts and nuts, and the first or second earth retaining panel 1 or 2 adjacent to the left and right are connected with bolts and nuts to construct the structure 101 or 102. In addition, concrete or mortar is filled between the structures 101 and 102 and the wall surface of the excavation hole 201 as a backfill injection material.

[0035] The retaining structure 100 is constructed to include a structure in which, in the hole axis direction X of the excavation hole 201, a structure 101 made of retaining panels 1 having a small section modulus is placed between the retaining panels 101, and a structure 102 made of retaining panels 2 having a larger section modulus than the retaining panels 1 of the retaining structures 101.

[0036] The retaining structure 100 is not limited to a circular shape in plan view. The retaining structure 100 may be rectangular, oval, or U-shaped, such as a horseshoe, in plan view. The first retaining panel 1 and the second retaining panel 2 are configured to have a shape that corresponds to the shape of the retaining structure 100.

[0037] As described above, the retaining structure 100 according to the first embodiment is constructed by stacking annular structures (101, 102) in a plurality of stages along the hole axis direction X in a borehole 201 formed by excavating the ground 200. Each structure (101, 102) is configured by arranging a plurality of retaining panels (1, 2) having the same section modulus in a ring shape. The section modulus of the retaining panels (1, 2) of the structures (101, 102) of each stage is the same as or different from the section modulus of the retaining panels (1, 2) of the structures (101, 102) of the other stages. In the hole axis direction X of the borehole 201, a structure is included in which a structure 102 composed of a retaining panel 2 having a larger section modulus than the retaining panel 1 of the structure 101 is arranged between the structures 101 composed of the retaining panels 1 having a smaller section modulus.

[0038] The earth retaining panels (1, 2) have a first earth retaining panel 1 and a second earth retaining panel 2 having a larger section modulus than the first earth retaining panel 1. The first earth retaining panel 1 is a corrugated steel plate. The second earth retaining panel 2 has a skin plate 20 facing the wall surface of the borehole 201, main girders 21 provided at the upper and lower ends of the skin plate 20 to form the upper and lower surfaces, and joint plates 22 provided at both the left and right ends of the skin plate 20 to form the left and right side surfaces.

[0039] Therefore, in the retaining structure 100 according to the first embodiment, the rigidity of the entire structure can be increased by arranging the structural body 102 made up of the retaining panels 2 having a large section modulus and high rigidity in the borehole 201 where the earth pressure acts strongly and in the deep part of the borehole 201. Therefore, since the installation of the reinforcing ring can be omitted, the construction period and the construction cost can be shortened, and the workability and safety can be improved.

[0040] Embodiment 2 Next, an earth-retaining structure 100A according to the second embodiment will be described based on Figs. 9 to 12 with reference to Figs. 1 to 8. Fig. 9 is a front view showing a schematic diagram of the earth-retaining structure according to the second embodiment. Fig. 10 is a perspective view showing an example of a first earth-retaining panel constituting the earth-retaining structure according to the second embodiment. Fig. 11 is a vertical cross-sectional view of the first earth-retaining panel shown in Fig. 10. Fig. 12 is an explanatory diagram showing the relationship between the connection holes of the first earth-retaining panel and the connection holes of the second earth-retaining panel in the earth-retaining structure according to the second embodiment. Note that the same components as those in the first embodiment are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0041] As shown in Figure 9, the retaining structure 100A of this embodiment 2 is also configured in the hole axis direction X of the excavation hole 201 to include a structure 101 composed of a first retaining panel 1 having a small section modulus, and a structure 102 composed of a second retaining panel 2 having a larger section modulus than the first retaining panel 1 of the structure 101, arranged between the structures 101, thereby increasing the rigidity of the entire structure.

[0042] The retaining structure 100A according to the second embodiment differs from the structure described in the first embodiment in the structure of the first retaining panel 1. As shown in Figs. 10 and 11, the first retaining panel 1 according to the second embodiment is made of a corrugated steel plate made of a plank plate 1B. The plank plate 1B has a larger section modulus and higher rigidity than the liner plate 1A. In other words, the retaining structure 100A according to the second embodiment is preferably applied to a borehole 201 with a larger earth pressure than the retaining structure 100 according to the first embodiment.

[0043] The plank plate 1B has a rectangular corrugated cross section. The plank plate 1B is formed in an arc shape when viewed from above. The plank plate 1B has a thickness of, for example, about 2.7 mm to 7 mm. As shown in Figs. 10 and 11, the plank plate 1B is provided with an arc-shaped circumferential flange portion 10 that forms the upper and lower surfaces, and an axial flange portion 11 provided along both end edges in the arc direction. The axial flange portion 11 is formed by welding a plate to both end edges in the arc direction of the plank plate 1B.

[0044] The circumferential flange portion 10 has a plurality of connecting holes 10a formed along the arc direction for connecting adjacent first retaining panels 1 stacked in the hole axis direction X, or connecting the first retaining panel 1 and the second retaining panel 2. The adjacent first retaining panels 1 are connected by butting the circumferential flange portions 10 together and fastening the shafts of bolts inserted into the connecting holes 10a with nuts, for example. The means for connecting the circumferential flange portions 10 of adjacent first retaining panels 1 may be, for example, a connector such as a clip. The number of connecting holes 10a shown in the figure is merely an example and is not limited to this.

[0045] The axial flange portion 11 has a plurality of connecting holes 11a formed in the vertical direction for connecting adjacent first retaining panels 1 arranged in the circumferential direction of the excavation hole 201. Adjacent first retaining panels 1 are connected by butting the axial flange portions 11 together and fastening the shanks of bolts inserted into the connecting holes 11a with nuts. The means for connecting the axial flange portions 11 of adjacent first retaining panels 1 may be, for example, a connector such as a clip. The number of connecting holes 11a shown in the figure is merely an example and is not limited to this.

[0046] The second soil retaining panel 2 has the configuration described in the above embodiment 1 based on Figs. 4 to 6. The connecting hole 10a formed in the first soil retaining panel 1 is the first connecting hole, and the connecting hole 21a formed in the second soil retaining panel 2 is the second connecting hole. For example, as shown in Fig. 12, the first connecting hole 10a and the second connecting hole 21a are formed at the same position B from the end A on the inner diameter side of the soil retaining structure 100A toward the outer diameter side. In other words, the first connecting hole 10a and the second connecting hole 21a are formed at equal distances from the end A in the radial direction of the soil retaining structure 100A. With this configuration, the end face on the inner diameter side of the second soil retaining panel 2 and the end face on the inner diameter side of the first soil retaining panel 1 can be aligned, so that the effective diameter of the soil retaining structure 100A can be increased. In addition, since the inner diameter end face of the second soil retaining panel 2 does not protrude further into the inner diameter of the soil retaining structure 100A than the inner diameter end face of the first soil retaining panel 1, the internal space is wider, ensuring a working space for workers. Note that the same position from the inner diameter end A of the soil retaining structure 100A does not have to be strictly the same position, and some dimensional error is acceptable. Also, although not shown in the figures, the position of the outer surface of the first soil retaining panel 1 and the position of the outer surface of the second soil retaining panel 2 may be aligned.

[0047] As described above, in the earth-retaining structure 100A according to the second embodiment, the structure 102 made up of the earth-retaining panels 2 with a large section modulus and high rigidity is arranged in the borehole 201 where the earth pressure acts strongly and in the deep part of the borehole 201, so that the rigidity of the entire structure can be increased. Therefore, the installation of reinforcing rings can be omitted, so that the construction period and construction costs can be shortened, and workability and safety can be improved.

[0048] Embodiment 3 Next, an earth retaining structure 100B according to the third embodiment will be described based on Fig. 13 while referring to Figs. 1 to 12. Fig. 13 is a front view showing a schematic view of the earth retaining structure according to the third embodiment. Note that the same components as those in the first and second embodiments are given the same reference numerals and the description thereof will be omitted as appropriate.

[0049] As shown in Figure 13, the retaining structure 100B of this embodiment 3 is also configured in the hole axis direction X of the excavation hole 201, including a structure 101 composed of a first retaining panel 1 having a small section modulus, and a structure 102 composed of a second retaining panel 2 having a larger section modulus than the first retaining panel 1 of the structure 101, arranged between the structures 101, thereby increasing the rigidity of the entire structure.

[0050] In the earth-retaining structure 100B according to the third embodiment, the structure of the first earth-retaining panel 1 is different from that described in the first and second embodiments. The first earth-retaining panel 1 is composed of both a corrugated steel plate made of a liner plate 1A and a corrugated steel plate made of a plank plate 1B having a larger section modulus than the liner plate 1A. The corrugated steel plate made of the liner plate 1A is as described in the first embodiment based on Figs. 2 and 3. The corrugated steel plate made of the plank plate 1B is as described in the second embodiment based on Figs. 10 and 11. The second earth-retaining panel 2 is as described in the first and second embodiments based on Figs. 4 to 7 and 12.

[0051] In the earth retaining structure 100B according to the third embodiment, as shown in FIG. 13, in the hole axis direction X of the borehole 201, a structure 101 made of a plank plate 1B having a larger section modulus than the liner plate 1A is arranged between the structures 101 made of the liner plate 1A. In addition, in the hole axis direction X of the borehole 201, a structure 102 made of a second earth retaining panel 2 having a larger section modulus than the liner plate 1A and the plank plate 1B is arranged between the structures 101 made of the liner plate 1A. In other words, the earth retaining structure 100B according to the third embodiment is configured to increase the rigidity of the entire structure by using earth retaining panels (1, 2) according to the magnitude of the earth pressure of each stage and the depth. Note that the arrangement of the structures (101, 102) shown in FIG. 13 is an example, and is not limited thereto. For example, the structure 102 made of the second earth retaining panel 2 may be arranged between the structures 101 made of the plank plate 1B.

[0052] As described above, in the earth-retaining structure 100B according to the third embodiment, the structure 102 made up of the earth-retaining panels 2 with a large section modulus and high rigidity is arranged in the borehole 201 where the earth pressure acts strongly and in the deep part of the borehole 201, so that the rigidity of the entire structure can be increased. Therefore, the installation of reinforcing rings can be omitted, so that the construction period and construction costs can be shortened, and workability and safety can be improved.

[0053] Embodiment 4 Next, an earth retaining structure 100C according to the fourth embodiment will be described based on Fig. 14 with reference to Figs. 1 to 12. Fig. 14 is a front view showing a schematic view of the earth retaining structure according to the fourth embodiment. Note that the same components as those in the first and second embodiments are given the same reference numerals and the description thereof will be omitted as appropriate.

[0054] As shown in Fig. 14, the retaining structure 100C according to the fourth embodiment includes a structure in which a structure 101 made of a corrugated steel plate made of a plank plate 1B having a larger section modulus than that of the liner plate 1A is arranged between structures 101 made of a corrugated steel plate made of a liner plate 1A in the hole axis direction X of the borehole 201, thereby increasing the rigidity of the entire structure. The corrugated steel plate made of the liner plate 1A is as described in the first embodiment with reference to Figs. 2 and 3. The corrugated steel plate made of the plank plate 1B is as described in the second embodiment with reference to Figs. 10 and 11.

[0055] The retaining structure 100C according to the fourth embodiment is preferably applied to a borehole 201 where the earth pressure is smaller than those of the first to third embodiments, or to a shallow portion of the borehole 201. In the retaining structure 100C according to the fourth embodiment, the rigidity of the entire structure can be increased by disposing a structure 102 made of a plank plate 1B having a large section modulus and high rigidity. Therefore, the installation of a reinforcing ring can be omitted, so that the construction period and the construction cost can be shortened, and the workability and safety can be improved.

[0056] Although the earth retaining structure (100, 100A, 100B, 100C) has been described above based on the embodiment, it is not limited to the configuration of the above-mentioned embodiment. For example, the construction method of the earth retaining structure 100 described based on FIG. 8 is one example and is not limited to the above-mentioned embodiment. In addition, the first earth retaining panel 1 is not limited to the liner plate 1A and the plank plate 1B shown in the figure, and may be an earth retaining panel having another form. In addition, the second earth retaining panel 2 is not limited to the configuration shown in FIG. 4 to FIG. 6, and may be another form as long as it has a section modulus larger than that of the first earth retaining panel 1. In addition, the earth retaining structure (100, 100A, 100B, 100C) is not limited to the three types of earth retaining panels shown in the figure, and may be configured by combining four or more types of earth retaining panels. In short, the earth retaining structure (100, 100A, 100B, 100C) includes the range of design changes and application variations that are normally made by a person skilled in the art, within the scope of the technical idea. [Explanation of symbols]

[0057] 1 first earth retaining panel (earth retaining panel), 1A liner plate, 1B plank plate, 2 second earth retaining panel (earth retaining panel), 10 circumferential flange portion, 10a connection hole (first connection hole), 11 axial flange portion, 11a connection hole, 20 skin plate, 21 main girder, 21a connection hole (second connection hole), 21b drilled hole, 22 joint plate, 22a connection hole, 22b drilled hole, 23 shape retention member, 100, 100A, 100B, 100C earth retaining structure, 101, 102 structure, 200 ground, 201 borehole, 300 girder.

Claims

1. A retaining structure constructed by stacking annular structures with the same inner diameter in a plurality of stages along the hole axis direction in a borehole formed by excavating the ground, Each of the structures is formed by arranging a plurality of earth retaining panels having the same section modulus in an annular shape; The section modulus of the earth retaining panel of each stage of the structure is the same as or different from the section modulus of the earth retaining panel of the other stage of the structure; The earth retaining panel includes a first earth retaining panel and a second earth retaining panel having a section modulus larger than that of the first earth retaining panel, In the hole axis direction of the borehole, a structure composed of the second earth retaining panel having a larger section modulus than the first earth retaining panel of the structure is arranged between the structures composed of the first earth retaining panel having a smaller section modulus, The first retaining panel comprises: An arc-shaped circumferential flange portion provided along an upper end edge and a lower end edge; an axial flange portion provided along both end edges in the arc direction of the circumferential flange portion; A corrugated steel plate is provided on the wall surface of the borehole, The second retaining panel is A rectangular skin plate facing the wall surface of the borehole; A main beam is provided at the upper end and the lower end of the skin plate to form an upper surface and a lower surface; Joint plates are provided at both left and right ends of the skin plate to form left and right side surfaces; and The outer diameter side end of the structure formed by the first soil retaining panel is located on the inner diameter side of the outer diameter side end of the structure formed by the second soil retaining panel, The end face of the second retaining panel on the inner diameter side and the end face of the first retaining panel on the inner diameter side are aligned, As the depth in the borehole increases, the number of structures made up of the second earth retaining panels increases. Earth retaining structure.

2. The retaining structure of claim 1, wherein the first retaining panel is composed of either one or both of a corrugated steel plate made of a liner plate and a corrugated steel plate made of a plank plate having a larger section modulus than the liner plate.

3. The retaining structure according to claim 1 or 2, wherein the second retaining panel is provided between the upper and lower main girders and further comprises a shape retaining member that retains the shape of the second retaining panel.

4. The first retaining panel is formed with a first connecting hole for connecting to the second retaining panel, The second retaining panel has a second connecting hole for connecting to the first retaining panel, The retaining structure according to any one of claims 1 to 3, wherein the first connecting hole and the second connecting hole are formed at the same position from the inner diameter side end toward the outer diameter side.

5. The retaining structure according to any one of claims 1 to 4, wherein a drilled hole is formed in at least one of the main girder or the joint plate.

6. The retaining structure according to any one of claims 1 to 5, wherein the section modulus of the second retaining panel is set by adjusting at least one of the plate thickness or girder height of the main girder.

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