JP7543162B2 - Steel earth retaining panel, earth retaining structure using said steel earth retaining panel, and construction method for said earth retaining structure - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act. An explanation was given in the conference room of Kotsu Kensetsu Co., Ltd.'s Fuchu Branch on November 10, 2020.

Application of Article 30, Paragraph 1 of the Patent Act The construction method was carried out on January 25, 2021 near Shimojuku 2-553, Kiyose City, Tokyo.

The present invention relates to a steel retaining panel, a retaining structure using the steel retaining panel, and a construction method for the retaining structure.

As disclosed in Patent Document 1, for example, there is a known earth retaining structure constructed by assembling corrugated steel plates in a vertical borehole formed by excavating the ground. The earth retaining structure is constructed by stacking annular bodies formed by arranging corrugated steel plates in a ring shape along the wall surface of the borehole in the axial direction of the hole.

As the depth of an excavation hole increases, the earth pressure from the ground increases, and corrugated steel plates alone may not be strong enough. Also, as the hole axial depth increases, the weight of the rings placed above acts on the rings placed below. For this reason, in soil retaining structures, H-shaped steel called reinforcing rings are sandwiched between adjacent corrugated steel plates above and below in deep places to increase the rigidity.

However, the construction of the reinforcing rings is complicated and time-consuming, which lengthens the construction period and increases the construction costs. Therefore, there is a demand for the construction of an earth retaining structure that can omit the reinforcing rings. For example, in the shallow part of the excavation hole where the earth pressure is small and a reinforcing ring is not necessary, a ring-shaped body can be constructed with an arc-shaped corrugated steel plate, and in the deep part of the excavation hole where the earth pressure is large and a reinforcing ring is necessary, a ring-shaped body can be constructed with an arc-shaped steel earth retaining panel. The steel earth retaining panel is a product with higher rigidity than the corrugated steel plate. The steel earth retaining panel is configured to have, for example, an arc-shaped skin plate that faces the wall surface of the excavation hole, arc-shaped main girders that are provided at the upper and lower ends of the skin plate and form the upper and lower surfaces, and joint plates that are provided at both ends in the arc direction of the skin plate and form both end faces in the arc direction.

JP 2020-066845 A

When constructing a ring-shaped annular body using arc-shaped corrugated steel plates, multiple corrugated steel plates are arranged in sequence along the circumferential direction of the wall surface of the borehole, and adjacent corrugated steel plates are connected to each other. At this time, the corrugated steel plate arranged last along the circumferential direction of the wall surface is installed so as to fit from the inside to the outside of the annular body into the space between the left and right corrugated steel plates already installed. Since the corrugated steel plate is thin and the dimensional difference between the inner diameter surface and the outer diameter surface of the arc is small, it can be easily fitted from the inside to the outside of the annular body into the space between the left and right corrugated steel plates already installed.

On the other hand, even when constructing a ring-shaped annular body using arc-shaped steel earth retaining panels, they are placed in order on multiple steel earth retaining panels along the circumferential direction of the wall of the excavation hole, and adjacent steel earth retaining panels are connected. In this case, the steel earth retaining panel placed last in the circumferential direction of the wall cannot be fitted from the inside to the outside of the annular body into the space between the already installed left and right steel earth retaining panels. This is because the girder height of the main girder of the steel earth retaining panel is large and there is a large difference in dimensions between the inner diameter side and the outer diameter side of the arc, so if an attempt is made to fit the steel earth retaining panel from the inside to the outside of the annular body into the space between the already installed left and right steel earth retaining panels, both ends of the outer surface will abut against the inner surfaces of the left and right steel earth retaining panels. Therefore, a method is adopted in which the wall surface surrounding the space is expanded and excavated, and the steel earth retaining panel is fitted into the space from the outside to the inside of the annular body using the expanded space created. The hole is backfilled after the last steel earth retaining panel is installed. Even when constructing a ring-shaped structure using steel retaining panels, holes must be drilled into the wall to install the final steel retaining panel, making construction complicated and time-consuming, lengthening the construction period and increasing construction costs.

The present invention aims to solve the above problems, and aims to provide a steel earth retaining panel that can improve workability when constructing an earth retaining structure by arranging steel earth retaining panels in sequence along the circumferential direction of the wall surface of a borehole, an earth retaining structure using the steel earth retaining panel, and a construction method for the earth retaining structure.

The steel earth retaining panel of the present invention is a steel earth retaining panel that is placed in an excavation hole formed by excavating the ground and is used to construct a ring-shaped earth retaining structure, and has an arc-shaped plan view, with at least one end face in the arc direction being formed at an angle relative to the radial direction of the excavation hole, and has an arc-shaped skin plate facing the wall surface of the excavation hole, and arc-shaped main girders provided at the upper and lower ends of the skin plate and forming the upper and lower surfaces, and the outer edges of the upper and lower main girders protrude toward the wall surface of the excavation hole more than the outer surface of the skin plate, and a concave space is formed between the outer edges of the main girders and the outer surface of the skin plate .

The retaining structure according to the present invention is constructed by installing steel retaining panels that are arc-shaped in plan view in a borehole formed by excavating the ground, and includes a first retaining structure section in which a ring-shaped body formed by arranging a plurality of the steel retaining panels in a ring shape along the wall surface of the borehole is constructed in at least one stage in the axial direction of the borehole, and each of the plurality of steel retaining panels that constitute the ring-shaped body has at least two steel retaining panels of the above configuration, and at least one of the pairs of end faces where the steel retaining panels that are adjacent in the circumferential direction butt together is formed at an angle to the radial direction of the borehole.

The method for constructing an earth retaining structure according to the present invention is a method for constructing an earth retaining structure of the above configuration, and includes the steps of: leaving one steel earth retaining panel of the above configuration and assembling the other steel earth retaining panels in order along the circumferential direction of the wall surface of the excavation hole to construct a part of a ring-shaped body; and sliding the remaining steel earth retaining panel circumferentially from the inside of the ring-shaped body into the space formed between the steel earth retaining panels located at both ends of the steel earth retaining panels assembled in order along the circumferential direction, inserting one end of the remaining steel earth retaining panel, and pushing the other end in the radial direction to fit it in.

In the present invention, a steel retaining panel is used that is arc-shaped in plan view and at least one end face in the arc direction is formed at an angle relative to the radial direction of the excavation hole, so that the steel retaining panel to be installed last can be slid circumferentially from the inside of the ring-shaped body into the space formed between the left and right steel retaining panels that have already been installed. This eliminates the need to excavate the wall surface surrounding the space, shortening the construction period and reducing construction costs, and improving workability.

1 is a perspective view showing a schematic view of an earth retaining structure according to a first embodiment of the present invention; FIG. 2 is a perspective view showing a liner plate as an example of a corrugated steel plate according to the first embodiment. FIG. 2 is a longitudinal cross-sectional view showing a liner plate as an example of a corrugated steel plate according to the first embodiment. FIG. 2 is a perspective view showing a plank plate as an example of a corrugated steel plate according to the first embodiment. FIG. 2 is a longitudinal sectional view showing a plank plate as an example of a corrugated steel plate according to the first embodiment. 1 is an oblique view showing a steel retaining panel according to embodiment 1. FIG. A cross-sectional plan view showing a steel retaining panel for embodiment 1. 1A is a front view showing a steel earth-retaining panel according to embodiment 1, and FIG. 1B is a left side view showing the steel earth-retaining panel. A cross-sectional plan view showing an example of a first retaining structure portion in the retaining structure of embodiment 1. FIG. 10 is an enlarged view of part A shown in FIG. 9 . FIG. 2 is an explanatory diagram illustrating a schematic example of a construction method for a retaining structure according to the first embodiment. 1 is an explanatory diagram showing a schematic diagram of the procedure for constructing a first retaining structure portion of the retaining structure of embodiment 1. FIG. FIG. 2 is an explanatory diagram specifically showing the features of the construction method for the retaining structure according to the first embodiment. FIG. 1 is an explanatory diagram showing a schematic diagram of an example of a conventional construction method for a retaining structure. A plan view showing a modified example of the steel retaining panel of embodiment 1. FIG. 16 is an enlarged view of the left side of the steel retaining panel shown in FIG. 15 . 16 is an enlarged schematic diagram showing a main portion of a retaining structure using the steel retaining panel shown in FIG. 15. A cross-sectional plan view showing an example of a first retaining structure portion in an earth retaining structure according to embodiment 2. A cross-sectional plan view showing the first steel retaining panel in embodiment 2. 1A is a front view showing the first steel earth-retaining panel in embodiment 2, and FIG. 1B is a left side view showing the first steel earth-retaining panel. A cross-sectional plan view showing the second steel retaining panel in embodiment 2. (A) is a front view showing the second steel earth-retaining panel in embodiment 2, (B) is a left side view showing the second steel earth-retaining panel, and (C) is a right side view showing the second steel earth-retaining panel. A cross-sectional plan view showing the third steel retaining panel in embodiment 2. (A) is a front view showing the third steel earth-retaining panel in embodiment 2, (B) is a left side view showing the third steel earth-retaining panel, and (C) is a right side view showing the third steel earth-retaining panel. A cross-sectional plan view showing a modified example of the first retaining structure part in the retaining structure of embodiment 2. A cross-sectional plan view showing a steel retaining panel in a modified example of embodiment 2. (A) is a front view of the third steel earth-retaining panel shown in Figure 26, (B) is a left side view of the third steel earth-retaining panel, and (C) is a right side view of the third steel earth-retaining panel.

Below, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding parts are given the same reference numerals, and their description 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.

Embodiment 1.
First, a steel earth retaining panel 1 according to a first embodiment, an earth retaining structure 100 using the steel earth retaining panel 1, and a construction method for the earth retaining structure 100 will be described with reference to Figures 1 to 14. Figure 1 is a perspective view showing a schematic view of the earth retaining structure according to the first embodiment.

As shown in FIG. 1, the retaining structure 100 is constructed by installing a corrugated steel plate 2 and a steel retaining panel 1 in a vertical borehole formed by excavating the ground. The 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. Specifically, the retaining structure 100 includes a second retaining structure 102 and a first retaining structure 101. The second retaining structure 102 is constructed by stacking four layers of annular bodies 102A formed by arranging corrugated steel plates 2 in a ring shape in a plan view in a ring shape in the hole axis direction. The second retaining structure 102 is assembled by arranging the corrugated steel plates 2 in a staggered pattern. The first retaining structure 101 is constructed by stacking two layers of annular bodies 101A formed by arranging steel retaining panels 1 in a ring shape in a plan view in a ring shape in the hole axis direction. The first retaining structure 101 is also assembled by arranging the steel retaining panels 1 in a staggered pattern. The number of stages of the first retaining structure 101 and the second retaining structure 102 is not limited to the configuration shown in the figure, and each may have at least one stage. The number of corrugated steel plates 2 and steel retaining panels 1 in the circumferential direction of the retaining structure 100 shown in Figure 1 is one example. The ring shape also includes, for example, an elliptical shape.

Figure 2 is a perspective view showing a liner plate as an example of a corrugated steel plate according to the first embodiment. Figure 3 is a vertical cross-sectional view showing a liner plate as an example of a corrugated steel plate according to the first embodiment. Figure 4 is a perspective view showing a plank plate as an example of a corrugated steel plate according to the first embodiment. Figure 5 is a vertical cross-sectional view showing a plank plate as an example of a corrugated steel plate according to the first embodiment.

The corrugated steel plate 2 is, for example, a liner plate 2A shown in FIG. 2 and FIG. 3 or a plank plate 2B shown in FIG. 4 and FIG. 5. The liner plate 2A has a configuration in which the corrugated cross section is formed in a sine curve shape. The plank plate 2B has a configuration in which the corrugated cross section is formed in a rectangular shape. As shown in FIG. 2 to FIG. 5, the corrugated steel plate 2 is provided with an arc-shaped circumferential flange portion 20 provided along the upper end edge and the lower end edge, and an axial flange portion 21 provided along both ends in the arc direction. The circumferential flange portion 20 is formed by bending so as to protrude from the upper end edge and the lower end edge of the corrugated steel plate 2 toward the inside of the drilling hole. The axial flange portion 21 is formed by welding a plate to both ends in the arc direction of the corrugated steel plate 2.

The corrugated steel plate 2 has a thickness of, for example, about 2.7 mm to 7 mm. In the retaining structure 100 shown in FIG. 1, the first and second stages from the top are made of corrugated steel plates 2 made of liner plates 2A, and the third and fourth stages from the top are made of corrugated steel plates 2 made of plank plates 2B. In the retaining structure 100, as the depth of the excavation hole increases, the earth pressure from the ground increases, and the weight of the ring-shaped body 102A arranged above acts on the ring-shaped body 102A arranged below. For this reason, plank plates 2B, which are more rigid than the liner plates 2A, are used in the third and fourth stages of the retaining structure 100. Note that all stages of the second retaining structure 102 may be made of liner plates 2A, or all stages may be made of plank plates 2B.

The circumferential flange portion 20 has a plurality of connecting holes 20a formed along the arc direction for connecting adjacent corrugated steel plates 2 stacked in the hole axis direction, or connecting the corrugated steel plate 2 and the steel retaining panel 1. The vertically adjacent corrugated steel plates 2 are connected by butting the circumferential flange portions 20 together and fastening the shafts of bolts inserted into the connecting holes 20a with nuts, for example. The means for connecting the circumferential flange portions 20 of adjacent corrugated steel plates 2 may be, for example, a connector such as a clip. The number of connecting holes 20a shown in the figure is an example and is not limited to this.

The axial flange portion 21 has multiple connection holes 21a formed in the vertical direction to connect adjacent corrugated steel plates 2 arranged in the circumferential direction of the drilled hole. Adjacent corrugated steel plates 2 are connected by butting the axial flange portions 21 together and fastening the shaft portions of bolts inserted into the connection holes 21a with nuts. The means for connecting the axial flange portions 21 of adjacent corrugated steel plates 2 may be, for example, a connector such as a clip. The number of connection holes 21a shown in the figure is an example and is not limited to this.

Figure 6 is a perspective view showing a steel earth retaining panel according to the first embodiment. Figure 7 is a plan cross-sectional view showing a steel earth retaining panel according to the first embodiment. Figure 8 (A) is a front view showing a steel earth retaining panel according to the first embodiment, and (B) is a left side view showing the steel earth retaining panel. Figure 9 is a plan cross-sectional view showing an example of a first earth retaining structure part in an earth retaining structure according to the first embodiment. The arrows in Figure 9 indicate the range of each steel earth retaining panel 1. Figure 10 is an enlarged view of part A shown in Figure 9.

As shown in Figures 6 to 8, the steel earth retaining panel 1 has an arc-shaped skin plate 10 facing the wall of the borehole, an arc-shaped main girder 11 provided at the upper and lower ends of the skin plate 10 to form the upper and lower surfaces, and joint plates 12 provided at both ends of the skin plate 10 in the arc direction to form both end faces in the arc direction, and is formed in a concave shape that opens toward the inside of the borehole. The skin plate 10, main girder 11, and joint plates 12 are each fixed by welding. The girder height of the main girder 11 varies depending on the soil quality and depth of the borehole, but is, for example, about 150 mm to 400 mm. In addition, the height of the steel earth retaining panel 1 in the hole axis direction is designed to be in the range of about 500 mm to 1000 mm, with 500 mm as the standard, taking into consideration the safety and efficiency of the workers who construct the earth retaining structure 100.

The steel earth retaining panel 1 also has a shape retention member 13 that is disposed between the upper and lower main girders 11 and that retains the shape of the steel earth retaining panel 1 during manufacture, transportation, and construction. The shape retention member 13 is composed of, for example, a plate-shaped member made of a steel plate or the like as shown in the figure, or a rod-shaped member made of a reinforcing bar or the like not shown in the figure. In the illustrated example, four shape retention members 13 are disposed at intervals in the arc direction. Note that the shape and number of shape retention members 13 are not limited to the illustrated example, and are determined taking into consideration, for example, the size and shape of the steel earth retaining panel 1, etc.

The main girder 11 has multiple connection holes 11a for connecting adjacent steel retaining panels 1 stacked in the hole axis direction, or connecting the steel retaining panels 1 and the corrugated steel plate 2. Vertically adjacent steel retaining panels 1 are connected by butting the main girders 11 together and fastening the shanks of bolts inserted into the connection holes 11a with nuts. Vertically adjacent steel retaining panels 1 and the corrugated steel plate 2 are connected by butting the main girder 11 and the circumferential flange portion 20 together and fastening the shanks of bolts inserted into the connection holes 11a and 20a with nuts.

The diameter of the connecting hole 11a is preferably larger than the diameter of the connecting hole 20a. The annular body 102A may have an error in roundness due to construction errors or low rigidity of the corrugated steel plate 2. If construction errors and roundness errors occur in the annular body 102A, the positions of the connecting holes 11a and 20a may be slightly misaligned, making it difficult to insert bolts into the connecting holes 11a and 20a. In other words, by making the diameter of the connecting hole 11a larger than the diameter of the connecting hole 20a, the construction errors and roundness errors of the annular body 102A formed by the corrugated steel plate 2 can be absorbed by the connecting hole 11a, and the bolts can be inserted into the connecting holes 11a and 20a. The position, size, and number of the connecting holes 11a are not limited to those shown in the figure, and may be appropriately changed and formed according to the shape and size of the steel retaining panel 1.

As shown in Figs. 6 and 7, the upper and lower main girders 11 have a plurality of gouging holes 11b spaced apart in the arc direction for inserting a tool to gouge the gap. Gouging means, for example, inserting an object into a gap and twisting it. One example of a tool is a rod-shaped member such as a steel rod. The gouging holes 11b are provided to align the positions of the connecting holes 11a for connecting adjacent steel retaining panels 1 vertically, or connecting a steel retaining panel 1 and a corrugated steel plate 2. The gouging holes 11b may be provided in only one of the upper and lower main girders 11, or both may be omitted. The position, size, and number of the gouging holes 11b are not limited to those shown in the figures, and may be changed as appropriate.

The joint plate 12 has multiple connection holes 12a for connecting adjacent steel retaining panels 1 arranged circumferentially around the excavation hole. Adjacent steel retaining panels 1 are connected by butting the joint plates 12 together and fastening the shafts of the bolts inserted into the connection holes 12a with nuts. The number of connection holes 12a shown in the figure is an example and is not limited to this.

6 and 8, the left and right joint plates 12 are provided with gouging holes 12b for inserting a tool to gouge the holes. The tool is, for example, a rod-shaped member such as a chisel. The gouging holes 12b are provided for the purpose of aligning the positions of the connecting holes 12a of the steel retaining panels 1 adjacent to each other on the left and right. The gouging holes 12b may also be used to align the positions of the connecting holes 11a for connecting the steel retaining panels 1 adjacent to each other on the top and bottom, or the steel retaining panels 1 and the corrugated steel plate 2. The gouging holes 12b may be provided in only one of the left and right joint plates 12, or both may be omitted. The positions, sizes, and numbers of the gouging holes 12b are not limited to those shown in the drawings, and may be changed as appropriate.

As shown in Figs. 6 and 7, the steel earth retaining panel 1 is arc-shaped in plan view, and both end faces in the arc direction are inclined with respect to the radial direction of the excavation hole. Specifically, in plan view, both ends of the main girder 11 in the arc direction and the joint plate 12 of the steel earth retaining panel 1 are inclined with respect to the radial direction of the excavation hole. In other words, as shown in Figs. 9 and 10, in an annular body 101A constructed by arranging a plurality of steel earth retaining panels 1 in a ring shape, the pair of end faces where the steel earth retaining panels 1 adjacent in the circumferential direction butt together are inclined with respect to the radial direction of the excavation hole. Note that inclination with respect to the radial direction of the excavation hole means that the steel earth retaining panel 1 to be installed last is inclined to such an extent that it can be slid circumferentially from the inside of the annular body 101A into the space formed between the already installed left and right steel earth retaining panels 1 and 1.

Next, the construction method of the earth retaining structure 100 will be described with reference to Figures 11 to 13. Figure 11 is an explanatory diagram that shows a schematic example of a construction method of the earth retaining structure according to the first embodiment. Figure 12 is an explanatory diagram that shows a schematic procedure for constructing the first earth retaining structure part of the earth retaining structure according to the first embodiment. Figure 13 is an explanatory diagram that shows specific features of the construction method of the earth retaining structure according to the first embodiment. Note that the numbers in parentheses shown in Figures 12 and 13 indicate the numbers of the pieces of the steel earth retaining panel 1.

In the construction method for the earth retaining structure 100 according to the first embodiment, after constructing the second earth retaining structure portion 102, the first earth retaining structure portion 101 is constructed below the second earth retaining structure portion 102. First, as shown in FIG. 11(A), a borehole 201 for constructing the earth 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 earth retaining structure 100. The depth of the borehole 201 is, for example, about 0.5 m to 1.5 m. Then, a circular body 102A is assembled by arranging arc-shaped corrugated steel plates 2 in a ring shape along the wall surface of the borehole 201.

The annular body 102A is assembled by sequentially arranging the corrugated steel plates 2 along the circumferential direction of the wall surface of the borehole 201, and connecting the adjacent corrugated steel plates 2 on the left and right with bolts and nuts. At this time, the corrugated steel plate 2 arranged last in the circumferential direction of the wall surface is installed so as to be fitted from the inside to the outside of the annular body 102A into the space formed between the left and right corrugated steel plates 2. Since the corrugated steel plate 2 has a thin plate thickness and a small dimensional difference between the inner diameter surface and the outer diameter surface of the arc, it can be fitted from the inside to the outside of the annular body 102A into the space formed between the left and right corrugated steel plates 2. The corrugated steel plate 2 of the upper annular body 102A and the corrugated steel plate 2 of the lower annular body 102A are connected with bolts and nuts. The corrugated steel plate 2 of the upper stage and the corrugated steel plate 2 of the lower stage are arranged with the circumferential positions shifted so as to be staggered. In this way, a portion of the second retaining structure 102 is constructed by stacking the annular bodies 102A in multiple tiers (three tiers in the illustrated example) along the hole axis direction.

Next, as shown in Figure 11 (B), the topmost ring-shaped body 102A is fixed with a lattice 300 installed on the ground 200, and the excavation hole 201 outside the ring-shaped body 102A is then backfilled with excavated soil. Note that the means for fixing the topmost ring-shaped body 102A to the ground is not limited to the lattice 300, and concrete may be used, for example. Then, as shown in Figure 11 (C), the ground is excavated while assembling the ring-shaped bodies 102A and 101A to construct the second retaining structure 102 and the first retaining structure 101, and digging is continued to a predetermined depth. After the topmost ring-shaped body 102A is fixed with the lattice 300, a corrugated steel plate 2 is placed at the bottom end of the bottommost ring-shaped body 102A along the circumferential direction of the wall surface of the drilled hole 201, and the corrugated steel plate 2 is connected to the bottommost corrugated steel plate 2 with bolts and nuts, and adjacent corrugated steel plates 2 on the left and right are connected to each other with bolts and nuts to construct the ring-shaped body 102A. In addition, concrete or mortar is filled between the corrugated steel plate 2 and the drilled hole 201 as a backfill injection material.

The first retaining structure 101 is constructed at the bottom end of the second retaining structure 102 after the second retaining structure 102 is constructed by stacking four annular bodies 102A, formed by arranging arc-shaped corrugated steel plates 2 in a ring shape, in the hole axis direction. Each annular body 101A constituting the first retaining structure 101 shown in FIG. 12 is, as an example, composed of six steel retaining panels 1 of the same shape and size.

Specifically, as shown in FIG. 12(A), the first to fifth pieces of steel earth retaining panels 1 are assembled in order along the circumferential direction of the wall surface of the excavation hole 201, leaving one sixth piece of steel earth retaining panel 1, to construct a part of the annular body 101A. The first to fifth pieces of steel earth retaining panels 1 are connected to the upper corrugated steel plate 2 or the upper steel earth retaining panel 1 with bolts and nuts, and adjacent steel earth retaining panels 1 on the left and right are connected to each other with bolts and nuts. The upper corrugated steel plate 2 or the upper steel earth retaining panel 1 and the lower steel earth retaining panel 1 are staggered in the circumferential position so as to form a staggered arrangement.

Then, as shown in FIG. 12(B), the remaining sixth piece of steel earth retaining panel 1 is inserted into the space S formed between the first piece of steel earth retaining panel 1 and the fifth piece of steel earth retaining panel 1 by sliding it circumferentially from the inside of the annular body 101A. At this time, as shown in FIG. 13, one joint plate 12 of the sixth piece of steel earth retaining panel 1 is slid relative to one joint plate 12 of the fifth piece of steel earth retaining panel 1. After one end side of the sixth piece of steel earth retaining panel 1 is slid and inserted into the space S between the first piece of steel earth retaining panel 1 and the fifth piece of steel earth retaining panel 1, as shown in FIG. 12(C) and FIG. 13, the other end side of the sixth piece of steel earth retaining panel 1 is pushed from the inside of the annular body 101A toward the outside (the direction of the arrow X in the figure) and fitted into the space S. The sixth piece of steel earth retaining panel 1 is then connected to the upper corrugated steel plate 2 or steel earth retaining panel 1 with bolts and nuts, and is also connected to the adjacent steel earth retaining panels 1 on the left and right with bolts and nuts. Concrete or mortar is filled between the steel earth retaining panel 1 and the excavation hole as a backfill injection material. The sixth piece of steel earth retaining panel 1, which is installed last, is preferably shorter in the arc direction than the other steel earth retaining panels 1, for example, by about 0 mm to 6 mm, and more preferably by about 3 mm. This is to make it easier to insert the sixth piece of steel earth retaining panel 1 into the space S and to improve the workability of assembly.

Figure 14 is an explanatory diagram that shows a schematic example of a conventional construction method for an earth retaining structure. The numbers in parentheses in Figure 14 indicate the numbers of the pieces of the steel earth retaining panel 3.

In the steel earth retaining panel 3 shown in FIG. 14, in plan view, both end faces and joint plates in the arc direction of the main girder are configured to face the radial direction of the excavation hole. In the construction method of the conventional earth retaining structure 100, the annular body of the first earth retaining structure part is constructed by first assembling the first to fifth pieces of steel earth retaining panels 3 in order from the inside of the annular body along the circumferential direction of the wall surface of the excavation hole 201. The sixth piece of steel earth retaining panel 3, which is placed last, cannot be fitted from the inside to the outside of the annular body into the space S between the first piece of steel earth retaining panel 3 and the fifth piece of steel earth retaining panel 3 that have already been installed. The steel earth retaining panel 3 has a large girder height of the main girder, and there is a large dimensional difference between the inner diameter side and the outer diameter side of the arc. Therefore, if the sixth piece of steel earth retaining panel 3 is to be fitted from the inside to the outside of the ring body into the space S between the first piece of steel earth retaining panel 3 and the fifth piece of steel earth retaining panel 3 that have already been installed, both ends of the outer surface of the sixth piece of steel earth retaining panel 3 will hit the inner surface of the first piece of steel earth retaining panel 3 or the inner surface of the fifth piece of steel earth retaining panel 3. Therefore, as shown in FIG. 14, a method is adopted in which the wall surface surrounding the space S is expanded and excavated, and the steel earth retaining panel 3 is fitted into the space S from the outside to the inside of the ring body (in the direction of arrow Y in the figure) using the expanded space 202 that is created. The expanded space 202 is backfilled after the last steel earth retaining panel 3 is installed.

As described above, the conventional construction method for earth retaining structures requires the creation of an expansion space 202 in the wall of each ring body to accommodate the steel earth retaining panel that is installed last, which makes construction complicated and time-consuming, lengthens the construction period, and increases construction costs.

The steel retaining panel 3 is lowered into the borehole 201 while suspended by a crane or the like installed on the ground, and is arranged along the circumferential direction of the wall of the borehole 201. However, if the steel retaining panel 3 is placed in the expansion space 202 while suspended by a crane or the like, and moved from the outside to the inside of the annular body, the crane's hoisting cord may get in the way of the upper corrugated steel plate or upper steel retaining panel that has already been installed, and the steel retaining panel 3 may not be able to be properly hoisted by the hoisting cord.

On the other hand, in the steel earth retaining panel 1 according to the first embodiment, the earth retaining structure 100 using the steel earth retaining panel 1, and the construction method for the earth retaining structure 100, a steel earth retaining panel 1 is used that is arc-shaped in plan view and has both end faces in the arc direction formed at an incline relative to the radial direction of the excavation hole. Therefore, the steel earth retaining panel 1 to be installed last can be slid circumferentially from the inside of the annular body 101A into the space S formed between the left and right steel earth retaining panels 1 already installed. In other words, since there is no need to excavate the wall surface surrounding the space S, it is possible to shorten the construction period and reduce construction costs, and improve workability.

The second retaining structure 102 is not limited to the four stages shown in the figure, and may have one or more stages. Furthermore, each annular body 101A constituting the first retaining structure 101 is not limited to the configuration formed by the six steel retaining panels 1 shown in the figure, and may be formed by a number other than six. Furthermore, the retaining structure 100 according to the first embodiment is not limited to a configuration having the second retaining structure 102 constructed of corrugated steel plates 2 and the first retaining structure 101 constructed of steel retaining panels 1, and although not shown in the figure, it may be composed of only the first retaining structure 101 constructed of steel retaining panels 1.

Figure 15 is a plan view showing a modified example of the steel earth retaining panel according to embodiment 1. Figure 16 is an enlarged view of the left side of the steel earth retaining panel shown in Figure 15. Figure 17 is an enlarged view showing a schematic of the main parts of an earth retaining structure using the steel earth retaining panel shown in Figure 15.

15 to 17, the upper main girder 11 may be provided so that its outer edge 11c protrudes toward the wall of the borehole 201 beyond the outer surface of the skin plate 10. The lower main girder 11 is also provided so that its outer edge 11c protrudes toward the wall of the borehole 201 beyond the outer surface of the skin plate 10. The outer edge 11c here refers to the part that protrudes toward the wall of the borehole 201 beyond the outer surface of the skin plate 10. The protruding length of the outer edge 11c of the main girder 11 is, for example, about 25 mm. The outer edges 11c of the upper and lower main girders 11 and the outer surface of the skin plate 10 form a concave space S into which the backfill injection material 203 filled between the outer surface of the earth retaining structure 100 and the borehole 201 enters. In other words, the steel retaining panel 1 can form an anchorage gap for the backfill injection material 203 that has been filled between the wall surface of the excavation hole 201 and the steel retaining panel 1 and hardened, by using the concave space S, thereby improving the anchorage of the backfill injection material 203.

Although not shown in the figures, the steel retaining panel 1 may be configured so that the outer edge 11c of either the upper or lower main girder 11 protrudes toward the wall surface of the excavation hole 201 beyond the outer surface of the skin plate 10. Even in this case, a concave space S is formed between the outer edge 11c of the protruding main girder 11 and the outer surface of the skin plate 10, so that a fixing allowance can be formed for the backfill injection material 203 that has been filled and hardened between the wall surface of the excavation hole 201 and the steel retaining panel 1 to catch on, thereby improving the fixing ability of the backfill injection material 203.

Embodiment 2.
Next, a steel earth retaining panel according to the second embodiment, an earth retaining structure using the steel earth retaining panel, and a construction method for the earth retaining structure will be described based on Figs. 18 to 24 with reference to Figs. 1 to 17. Fig. 18 is a plan sectional view showing an example of a first earth retaining structural part in the earth retaining structure according to the second embodiment. The arrows shown in Fig. 18 indicate the ranges of the steel earth retaining panels 1A to 1C. Note that the same components as those in the first embodiment are given the same reference numerals, and their description will be omitted as appropriate.

As shown in FIG. 1, the earth retaining structure according to the second embodiment also includes a second earth retaining structure 102 constructed by stacking multiple annular bodies 102A formed by arranging arc-shaped corrugated steel plates 2 in a ring shape in the hole axis direction, and a first earth retaining structure 101 constructed by stacking multiple annular bodies 101A formed by arranging arc-shaped steel earth retaining panels 1 in a ring shape in the hole axis direction. The number of stages of the first earth retaining structure 101 and the second earth retaining structure 102 is not limited to the configuration shown in the figure, and may be at least one stage. The ring shape also includes, for example, an elliptical shape.

As shown in FIG. 18, the retaining structure according to the second embodiment is characterized in that, in the steel retaining panels 1 constituting the annular body 101A of the first retaining structure 101, one of the pairs of end faces where adjacent steel retaining panels 1 in the circumferential direction butt together is formed at an incline with respect to the radial direction of the excavation hole.

The steel retaining panel 1 according to the second embodiment also has an arc-shaped skin plate 10 that faces the wall of the excavation hole, arc-shaped main girders 11 that are provided at the upper and lower ends of the skin plate 10 and form the upper and lower surfaces, and joint plates 12 that form both end faces in the arc direction, and is configured in a concave shape that opens toward the inside of the excavation hole.

In the earth-retaining structure according to the second embodiment, each annular body 101A is constructed by combining three types of steel earth-retaining panels. The annular body 101A shown in FIG. 18 has seven steel earth-retaining panels 1 consisting of five first steel earth-retaining panels 1A, one second steel earth-retaining panel 1B, and one third steel earth-retaining panel 1C. The first steel earth-retaining panel 1A, the second steel earth-retaining panel 1B, and the third steel earth-retaining panel 1C each have a different orientation of the end face and joint plate 12 in the arc direction of the main girder 11.

Figure 19 is a plan cross-sectional view showing the first steel earth retaining panel in embodiment 2. Figure 20 (A) is a front view showing the first steel earth retaining panel in embodiment 2, and (B) is a left side view showing the first steel earth retaining panel. The first steel earth retaining panels 1A are all constructed with the same shape and size. As shown in Figures 19 and 20, the first steel earth retaining panels 1A are configured such that the end faces in the arc direction of the main girder 11 and the joint plate 12 face the radial direction of the excavation hole in a plan view. Note that the first steel earth retaining panels 1A do not need to have the same length in the arc direction. In addition, the number of first steel earth retaining panels 1A is not limited to the five shown in the figure. The length and number of the first steel earth retaining panels 1A in the arc direction are appropriately changed depending on the shape and size of the excavation hole.

21 is a plan cross-sectional view showing the second steel earth retaining panel in the second embodiment. FIG. 22 (A) is a front view showing the second steel earth retaining panel in the second embodiment, (B) is a left side view showing the second steel earth retaining panel, and (C) is a right side view showing the second steel earth retaining panel. The length of the second steel earth retaining panel 1B in the arc direction is, for example, approximately half the length of the first steel earth retaining panel 1A in the arc direction. As shown in FIG. 21 and FIG. 22, the second steel earth retaining panel 1B is formed so that the left end surface in the arc direction is inclined relative to the radial direction of the excavation hole in a plan view. Specifically, the second steel earth retaining panel 1B is formed so that the left end portion in the arc direction of the main girder 11 and the joint plate 12 forming the left end surface in the arc direction are inclined relative to the radial direction of the excavation hole in a plan view.

23 is a plan cross-sectional view showing the third steel earth retaining panel in the second embodiment. FIG. 24 (A) is a front view showing the third steel earth retaining panel in the second embodiment, (B) is a left side view showing the third steel earth retaining panel, and (C) is a right side view showing the third steel earth retaining panel. The third steel earth retaining panel 1C has a length in the arc direction that is, for example, approximately half the length in the arc direction of the first steel earth retaining panel 1A. As shown in FIG. 23 and FIG. 24, the third steel earth retaining panel 1C is formed so that the right end surface in the arc direction is inclined relative to the radial direction of the excavation hole in a plan view. Specifically, the third steel earth retaining panel 1C is formed so that the right end portion in the arc direction of the main girder 11 and the joint plate 12 forming the right end surface in the arc direction are inclined relative to the radial direction of the excavation hole in a plan view.

Next, the construction method of the retaining structure 100 according to the second embodiment will be described with reference to FIG. 18. The process of constructing the second retaining structure portion 102 in the construction method of the retaining structure 100 according to the second embodiment is the same as that in the first embodiment.

The first retaining structure 101 is constructed at the bottom end of the second retaining structure 102 after the second retaining structure 102 is constructed by stacking multiple layers of annular bodies 102A, formed by arranging arc-shaped corrugated steel plates 2 in a ring shape, in the hole axis direction.

The construction of the ring-shaped body 101A of the first earth retaining structure 101 is carried out by first arranging the five first steel earth retaining panels 1A in order along the circumferential direction of the wall surface of the excavation hole, connecting them to the upper corrugated steel plate 2 or the upper steel earth retaining panel 1 with bolts and nuts, and connecting the first steel earth retaining panels 1A adjacent to each other on the left and right with bolts and nuts. Then, a second steel earth retaining panel 1B is arranged between the first steel earth retaining panels 1A located at both ends of the circumferential direction among the five first steel earth retaining panels 1A, and the second steel earth retaining panel 1B is connected to the upper corrugated steel plate 2 or the upper steel earth retaining panel 1 with bolts and nuts, and connected to the first steel earth retaining panel 1A adjacent to the left side with bolts and nuts. Then, a third steel earth retaining panel 1C is fitted into the space formed between the first steel earth retaining panel 1A and the second steel earth retaining panel 1B. The third steel earth-retaining panel 1C is inserted into the space formed between the first steel earth-retaining panel 1A and the second steel earth-retaining panel 1B by sliding it circumferentially from the inside of the annular body 101A. At this time, the inclined joint plate 12 of the third steel earth-retaining panel 1C is slid relative to the inclined joint plate 12 of the second steel earth-retaining panel 1B. Then, after sliding one inclined end side of the third steel earth-retaining panel 1C into the space formed between the first steel earth-retaining panel 1A and the second steel earth-retaining panel 1B, the other end side of the third steel earth-retaining panel 1C is pushed from the inside to the outside of the annular body 101A and fitted into the space. The third steel retaining panel 1C is then connected to the upper corrugated steel plate 2 or the upper steel retaining panel 1 with bolts and nuts, and is also connected to the first steel retaining panel 1A and the second steel retaining panel 1B adjacent to each other on the left and right with bolts and nuts. In addition, concrete or mortar is filled between the steel retaining panels (1A to 1C) and the excavation holes as a backfill injection material.

In addition, a third steel earth retaining panel 1C may be placed between the first steel earth retaining panels 1A located at both ends of the circumference among the five first steel earth retaining panels 1A, and connected to the first steel earth retaining panel 1A with bolts and nuts, and then the second steel earth retaining panel 1B may be fitted into the space formed between the first steel earth retaining panel 1A and the third steel earth retaining panel 1C.

In this way, the steel earth retaining panels (1A-1C) according to the second embodiment, the earth retaining structure 100 using the steel earth retaining panels (1A-1C), and the construction method for the earth retaining structure 100 also use a steel earth retaining panel 1 that is arc-shaped in plan view and has both end faces in the arc direction inclined relative to the radial direction of the excavation hole. Therefore, the third steel earth retaining panel 1C, which is installed last, can be slid circumferentially from the inside of the ring-shaped body 101A into the space formed between the already installed first steel earth retaining panel 1A and second steel earth retaining panel 1B on the left and right. In other words, since there is no need to excavate the wall surface around the space, the construction period can be shortened, construction costs can be reduced, and workability can be improved.

Although not shown in the figures, in the steel retaining panels 1 forming the annular body 101A, two or more of the pairs of end faces where adjacent steel retaining panels 1 in the circumferential direction butt together may be configured to be inclined relative to the radial direction of the excavation hole.

Next, based on Figs. 25 to 27, we will explain modified examples of the steel earth retaining panels (1A to 1C) according to the second embodiment and the earth retaining structure 100 using the steel earth retaining panels (1A to 1C). Fig. 25 is a cross-sectional plan view showing a modified example of the first earth retaining structure part in the earth retaining structure according to the second embodiment. The arrows in Fig. 25 indicate the range of each steel earth retaining panel (1A to 1C). Fig. 26 is a cross-sectional plan view showing a steel earth retaining panel in a modified example of the second embodiment. Fig. 27 (A) is a front view of the third steel earth retaining panel shown in Fig. 26, (B) is a left side view of the third steel earth retaining panel, and (C) is a right side view of the third steel earth retaining panel.

The modified example of the second embodiment shown in Figures 25 to 27 is characterized in that the length in the arc direction of the second steel earth retaining panel 1B is much shorter than that of the third steel earth retaining panel 1C. As an example, the length in the arc direction of the second steel earth retaining panel 1B and the third steel earth retaining panel 1C combined is approximately the same as that of the first steel earth retaining panel 1A. The length in the arc direction of the second steel earth retaining panel 1B is approximately 1/9 of the length in the arc direction of the third steel earth retaining panel 1C.

In this modified version of the second embodiment, the second steel earth retaining panel 1B is made much shorter and lighter than the third steel earth retaining panel 1C, which makes it easier to slide the second steel earth retaining panel 1B into the space formed between the left and right first steel earth retaining panel 1A and third steel earth retaining panel 1C, further improving workability.

The steel retaining panel 1, the retaining structure 100, and the construction method for the retaining structure 100 have been described above based on the embodiment, but the steel retaining panel 1, the retaining structure 100, and the construction method for the retaining structure 100 are not limited to the configuration of the above-mentioned embodiment. For example, the construction method for the retaining structure 100 described based on FIG. 11 is one example and is not limited to the above-mentioned embodiment. In short, the steel retaining panel 1, the retaining structure 100, and the construction method for the retaining structure 100 include the range of design changes and application variations that are normally made by a person skilled in the art, within the scope that does not deviate from the technical concept.

1 Steel retaining panel, 1A First steel retaining panel, 1B Second steel retaining panel, 1C Third steel retaining panel, 2 Corrugated steel plate, 2A Liner plate, 2B Plank plate, 3 Steel retaining panel, 10 Skin plate, 11 Main girder, 11a Connection hole, 11b Drilled hole, 11c Outer edge, 12 Joint plate, 12a Connection hole, 12b Drilled hole, 13 Shape retaining member, 20 Circumferential flange portion, 20a Connection hole, 21 Axial flange portion, 21a Connection hole, 100 Retaining structure, 101 First retaining structure portion, 101A Ring-shaped body, 102 Second retaining structure portion, 102A Ring-shaped body, 200 Ground, 201 Excavation hole, 202 Expansion space, 203 Backfill injection material, 300 Well.

Claims (7)

A steel earth retaining panel used to construct a ring-shaped earth retaining structure by being placed in a borehole formed by excavating the ground,
The plan view is arc-shaped, and at least one end face in the arc direction is inclined with respect to the radial direction of the drilling hole,
An arc-shaped skin plate facing the wall surface of the borehole;
An arc-shaped main girder is provided at the upper end and the lower end of the skin plate and forms an upper surface and a lower surface;
It has
The outer edges of the upper and lower main girders protrude toward the wall surface of the borehole beyond the outer surface of the skin plate,
A steel retaining panel in which a concave space is formed between the outer edge of each of the main girders and the outer surface of the skin plate . The skin plate further includes a joint plate provided at both ends in the arc direction and forming both end faces in the arc direction,
The steel retaining panel according to claim 1, wherein, in a plan view, the end faces of the main girder in the arc direction and the joint plates are formed at an incline with respect to the radial direction of the excavation hole. The steel retaining panel according to claim 1 or 2, further comprising a shape retention member provided between the upper and lower main girders and configured to retain the shape. A retaining structure constructed by installing a steel retaining panel having an arc-shaped plan view in a borehole formed by excavating the ground,
A ring-shaped structure formed by arranging a plurality of the steel earth retaining panels in a ring shape along the wall surface of the borehole includes a first earth retaining structure portion constructed in at least one stage in the hole axial direction;
A retaining structure, wherein each of the multiple steel retaining panels constituting the annular body has at least two steel retaining panels as described in any one of claims 1 to 3, and at least one of the pairs of end faces where adjacent steel retaining panels in the circumferential direction butt together is formed at an incline with respect to the radial direction of the excavation hole. The retaining structure according to claim 4, wherein all pairs of end faces where adjacent steel retaining panels in the circumferential direction butt together in the steel retaining panels forming each annular body are formed at an incline with respect to the radial direction of the excavation hole. A second retaining structure is further provided, in which a ring-shaped body formed by arranging a plurality of corrugated steel plates having an arc-shaped plan view in a ring shape along the wall surface of the borehole is constructed in at least one stage in the hole axial direction,
The earth retaining structure according to claim 4 or 5, wherein the first earth retaining structural portion is constructed below the second earth retaining structural portion. A method for constructing an earth retaining structure according to any one of claims 4 to 6,
A step of assembling the remaining steel earth retaining panels, except for one of the steel earth retaining panels according to claim 1 or 2, in sequence along the circumferential direction of the wall surface of the borehole to construct a part of the annular body;
A method for constructing an earth retaining structure, comprising the steps of: sliding the remaining steel earth retaining panel circumferentially from the inside of the annular body to insert one end of the steel earth retaining panel into a space formed between the steel earth retaining panels located at both ends of the steel earth retaining panels which are assembled in sequence along the circumferential direction, and then pushing the other end in the radial direction to fit it in.

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