JP7543170B2 - Steel earth retaining panel and earth retaining structure using said steel earth retaining panel - Google Patents

Description

The present invention relates to a steel earth retaining panel and an earth retaining structure using the steel earth retaining panel.

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 structures formed by arranging multiple 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 provide enough rigidity. In addition, regardless of the depth, the earth pressure may be high 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 deeper areas, H-shaped steel called reinforcing rings are sandwiched between adjacent corrugated steel plates above and below to increase rigidity.

However, the construction of the reinforcing ring is complicated and time-consuming, which lengthens the construction period and increases the construction costs. Therefore, it is desirable to construct an earth retaining structure that can omit the reinforcing ring. For example, in a shallow part of a borehole where the earth pressure is small and a reinforcing ring is not necessary, a structure can be constructed by arranging multiple corrugated steel plates in a ring shape along the wall surface of the borehole, and in a deep part of a borehole where the earth pressure is large and a reinforcing ring is necessary, a structure can be constructed by arranging multiple steel earth retaining panels in a ring shape along the wall surface of the borehole. The steel earth retaining panel is a product with higher rigidity than the corrugated steel plate. This steel earth retaining panel is equipped with a 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 the left and right ends of the skin plate to form the left and right side surfaces. The steel earth retaining panel is formed in a concave shape that opens toward the inside of the borehole by the skin plate, main girders, and joint plates. The skin plates, main girders and joint plates are each fixed by welding.

JP 2020-066845 A

A steel retaining panel with the above-mentioned configuration is known to have a structure with water-stopping properties. To achieve a water-stopping structure, the joints between the skin plate and the main girder, and between the skin plate and the joint plate, must be welded from the outer surface of the steel retaining panel. This is to completely seal the gaps between the skin plate and the main girder, and between the skin plate and the joint plate, from the outer surface, to prevent groundwater from entering the gaps.

However, in the process of welding the joints between the skin plate and the main girder, and the joints between the skin plate and the joint plate from the outer surface side of the steel earth retaining panel, the steel earth retaining panel must be turned over in the middle of assembly in order to weld the joints located at the bottom of the steel earth retaining panel. This is because there are some parts that cannot be welded unless the steel earth retaining panel is turned over. This is also to ensure the safety of the welding work and to increase the welding accuracy. The work of welding such heavy steel earth retaining panels while turning them over was a heavy burden for the workers. In addition, since the entire joint needs to be welded without any gaps, the number of parts that need to be welded increases, which may increase the welding man-hours and manufacturing costs.

On the other hand, corrugated steel plates are structures that do not have water-stopping properties. Retaining structures constructed using such corrugated steel plates that do not have water-stopping properties are constructed in places that are, for example, less susceptible to the effects of groundwater and do not require water-stopping properties. In other words, steel retaining panels that are used together with corrugated steel plates or in place of corrugated steel plates also do not need to have water-stopping properties.

The present invention aims to solve the above problems and provide a steel earth retaining panel and an earth retaining structure using the steel earth retaining panel, which is used in an earth retaining structure that does not require watertightness, and which can omit some or all of the welding work from the outer surface side of the steel earth retaining panel when welding the joints between the skin plate and the main girder and the joints between the skin plate and the joint plate, thereby improving the workability of the welding work and reducing the manufacturing effort and cost.

The steel earth-retaining panel of the present invention is a steel earth-retaining panel used to construct an earth-retaining structure by being installed in a borehole formed by excavating the ground, and comprises a skin plate facing the wall surface of the borehole, main girders provided at the upper and lower ends of the skin plate and forming the upper and lower surfaces, and joint plates provided at both left and right ends of the skin plate and forming the left and right side surfaces, and is formed in a concave shape that opens toward the inside of the borehole, and either one or both of the joints between the skin plate and the main girders and the joints between the skin plate and the joint plates are welded and joined from the concave inner side of the concave shape , and further comprises a shape-retaining member provided between the upper and lower main girders and which retains the shape of the concave shape, and the joints between the shape-retaining members and the skin plate are welded and joined from the concave inner side of the concave shape, and the joints between the shape-retaining members and the skin plate are formed alternately left and right along the vertical direction .

The retaining structure of the present invention is constructed by installing multiple steel retaining panels in a borehole formed by excavating the ground, and the structure formed by arranging the multiple steel retaining panels along the wall surface of the borehole includes a first retaining structure section constructed in at least one stage in the axial direction of the borehole, and the multiple steel retaining panels each include at least one of the steel retaining panels.

In the present invention, either or both of the joints between the skin plate and the main girder and the joints between the skin plate and the joint plate are welded from the inside of the concave shape, so that it is possible to omit some or all of the welding work from the outer surface side of the steel retaining panel. This makes it possible to increase the efficiency of the welding work and reduce the manufacturing effort and costs.

1 is a perspective view showing a schematic diagram of an earth retaining structure according to an 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 embodiment. FIG. 2 is a longitudinal sectional view showing a liner plate as an example of a corrugated steel plate according to the embodiment. FIG. 2 is a perspective view showing a plank plate as an example of a corrugated steel plate according to an embodiment. FIG. 2 is a vertical cross-sectional view showing a plank plate as an example of a corrugated steel plate according to an embodiment. FIG. 2 is an oblique view showing a steel retaining panel according to an embodiment of the present invention. 1 is a cross-sectional plan view showing a steel retaining panel according to an embodiment of the present invention. 1A is a front view showing a steel earth-retaining panel according to an embodiment of the present invention, and FIG. 1B is a left side view showing the steel earth-retaining panel. 9 is a cross-sectional view of part I shown in FIG. 8 as seen from the side. FIG. 9 is an enlarged view of part II shown in FIG. 8 . 9 is a cross-sectional view taken along line III-III in FIG. 8. 9 is a cross-sectional view of part II shown in FIG. 8 as seen from the side. An explanatory diagram showing modified example 1 of the shape retention member of the steel retaining panel in the embodiment. An explanatory diagram showing modified example 2 of the shape retention member of the steel retaining panel in the embodiment. FIG. 2 is an explanatory diagram showing a schematic example of a construction method for a retaining structure according to an embodiment of the present invention. A cross-sectional plan view showing an example of a first retaining structure part in an earth retaining structure according to an embodiment of the present invention. A cross-sectional plan view showing modified example 1 of a steel retaining panel according to an embodiment of the present invention. 17A is a front view of the steel earth retaining panel shown in FIG. 17, and FIG. 17B is a left side view of the steel earth retaining panel. This is a cross-sectional plan view showing an example of a first retaining structure portion in a retaining structure using the steel retaining panel shown in Figure 17. FIG. 20 is an enlarged view of part A shown in FIG. 19 . FIG. 20 is an explanatory diagram showing a schematic diagram of the procedure for constructing the first retaining structure portion of the retaining structure shown in FIG. 19 . FIG. 20 is an explanatory diagram specifically showing the features of the construction method for the retaining structure shown in FIG. 19. A plan view showing modified example 2 of the steel retaining panel of the embodiment. FIG. 24 is an enlarged view of the left side of the steel retaining panel shown in FIG. 23. This is an enlarged schematic diagram showing a main part of a retaining structure using the steel retaining panel shown in Figure 23. FIG. 13 is a perspective view showing a schematic diagram of a modified example of the earth retaining structure according to the embodiment. FIG. 11 is an oblique view showing a modified example of a steel retaining panel according to an embodiment of the present invention.

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
FIG. 1 is a perspective view showing a schematic diagram of an earth retaining structure according to an embodiment. As shown in FIG. 1, the earth retaining structure 100 is constructed by installing a corrugated steel plate 2 and a steel earth retaining panel 1 in a vertical excavation hole formed by excavating the ground. 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 in the ground. Specifically, the earth retaining structure 100 includes a second earth retaining structure portion 102 and a first earth retaining structure portion 101. The second earth retaining structure portion 102 is constructed by stacking four structures 102A formed by arranging corrugated steel plates 2 in a circular shape in a plan view in a circular shape in the hole axis direction. The second earth retaining structure portion 102 is assembled by arranging the corrugated steel plates 2 in a staggered manner. The first earth retaining structure 101 is constructed by stacking two layers of structures 101A in the hole axis direction, each structure being formed by arranging steel earth retaining panels 1 in a circular arc shape in plan view. The first earth retaining structure 101 is also assembled by arranging the steel earth retaining panels 1 in a staggered pattern. The earth retaining structure 100 is, as an example, configured to be circular in plan view.

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. Also, 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 an example and is not limited to this.

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

The corrugated steel plate 2 is composed of, for example, a liner plate 2A shown in Figs. 2 and 3, or a plank plate 2B shown in Figs. 4 and 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 Figs. 2 to 5, the corrugated steel plate 2 has an arc-shaped circumferential flange portion 20 provided along the upper and lower edges, 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 and lower edges 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, the earth pressure from the ground increases as the depth of the excavation hole increases, and the weight of the structure 102A arranged above acts on the structure 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 an embodiment. Figure 7 is a plan cross-sectional view showing a steel earth retaining panel according to an embodiment. Figure 8 (A) is a front view showing a steel earth retaining panel according to an embodiment, and (B) is a left side view showing the steel earth retaining panel. Figure 9 is a cross-sectional view of part I shown in Figure 8, seen from the side. Figure 10 is an enlarged view of part II shown in Figure 8. Figure 11 is a cross-sectional view taken along the line III-III shown in Figure 8. Figure 12 is a cross-sectional view of part II shown in Figure 8, seen from the side.

As shown in Figs. 6 to 8, the steel earth retaining panel 1 has an arc-shaped skin plate 10 facing the wall of the borehole, arc-shaped main girders 11 that are provided at the upper and lower ends of the skin plate 10 to form the upper and lower surfaces, and joint plates 12 that are provided at both ends of the skin plate 10 in the arc direction to form the left and right side surfaces. The steel earth retaining panel 1 is formed into a concave shape that opens toward the inside of the borehole by the skin plate 10, main girders 11, and joint plates 12. The skin plate 10, main girders 11, and joint plates 12 are each fixed by welding. The girder height of the main girders 11 varies depending on the soil quality and depth of the borehole, but is, for example, about 150 mm to 400 mm. 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 account the safety and efficiency of the workers who construct the earth retaining structure 100.

As shown in Figures 9 to 11, the steel retaining panel 1 is configured such that the joint 10a between the skin plate 10 and the main girder 11, and the joint 10b between the skin plate 10 and the joint plate 12 are welded from the inside of the concave recess. In other words, the joint 10a between the skin plate 10 and the main girder 11, and the joint 10b between the skin plate 10 and the joint plate 12 are not welded from the outer surface side of the steel retaining panel 1.

For example, a structure with water-stopping properties is known as a typical steel retaining panel. In order to achieve a water-stopping structure, the joints between the skin plate 10 and the main girder 11 and the joints between the skin plate 10 and the joint plate 12 must be welded from the outer surface of the steel retaining panel 1. This is to completely seal the gaps between the skin plate 10 and the main girder 11 and the gaps between the skin plate 10 and the joint plate 12 from the outer surface, preventing groundwater from entering the gaps.

However, in the work of welding the joints between the skin plate 10 and the main girder 11 and the joints between the skin plate 10 and the joint plate 12 from the outer surface side of the steel earth retaining panel 1, in order to weld the joints located at the bottom of the steel earth retaining panel 1, the steel earth retaining panel 1 must be turned over in the middle of assembly. This is because there are some parts that cannot be welded unless the steel earth retaining panel 1 is turned over. This is also to ensure the safety of the welding work and to increase the welding accuracy. The work of welding while turning over such a heavy steel earth retaining panel 1 was a heavy burden for the workers. In addition, since it is necessary to weld the entire joint without any gaps, the number of parts that need to be welded increases, which may increase the welding man-hours and increase the manufacturing effort and cost.

On the other hand, the corrugated steel plate 2 is a structure that does not have water-stopping properties. The retaining structure 100 constructed using such a corrugated steel plate 2 that does not have water-stopping properties is constructed in a place that is, for example, not easily affected by groundwater and does not require water-stopping properties. In other words, the steel retaining panel 1 used together with the corrugated steel plate 2 or used in place of the corrugated steel plate 2 also does not need to have water-stopping properties.

In other words, the steel retaining panel 1 according to this embodiment 1 is used in a retaining structure 100 that does not require watertightness, and the joint 10a between the skin plate 10 and the main girder 11, and the joint 10b between the skin plate 10 and the joint plate 12 are welded from the inside of the concave shape, eliminating the need to weld from the outer surface of the steel retaining panel 1.

It is desirable that the joint 10a be provided continuously without gaps along the arc direction to increase the joint strength, but it may be provided partially along the arc direction if sufficient joint strength can be obtained. Similarly, it is desirable that the joint 10b be provided continuously without gaps along the vertical direction to increase the joint strength, but it may be provided partially along the vertical direction if sufficient joint strength can be obtained.

The steel earth retaining panel 1 is not limited to a configuration in which both joints 10a and 10b are welded from the inside of the recess. The steel earth retaining panel 1 may be configured in which either one of joints 10a and 10b (10a or 10b) is welded from the inside of the recess. Even in this case, some of the welding work from the outer surface side of the steel earth retaining panel 1 can be omitted, which can increase the efficiency of the welding work and reduce the manufacturing effort and cost.

As shown in FIG. 11, for the same reasons as above, the joint 10c between the main girder 11 and the joint plate 12 is also welded from the inside of the recess to join them.

As shown in Figures 6 and 7, the main girder 11 has multiple connection holes 11a for connecting adjacent steel retaining panels 1 stacked vertically 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 girder 11 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 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 structure 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 structure 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 structure 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.

As shown in Figures 6 and 8, the joint plate 12 has multiple connection holes 12a for connecting adjacent steel retaining panels 1 arranged in the circumferential direction of 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 Figures 6 to 8, 10 and 12, the steel earth retaining panel 1 has shape retaining members 13 that are arranged between the upper and lower main girders 11 and retain the shape of the steel earth retaining panel 1 during manufacturing, transportation and construction. The shape retaining members 13 are formed of plate-like members made of steel plates with a thickness of, for example, about 6 mm. The shape retaining members 13 only need to have the strength to retain the shape of the steel earth retaining panel 1, so they may be thinner than the thickness of the joint plate 12, for example. In the illustrated example, four shape retaining members 13 are arranged at intervals in the arc direction. The thickness and number of shape retaining 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.

As shown in Figures 10 and 12, the shape-retaining member 13 has a structure in which the joints 13a with the inner surface of the skin plate 10 and the joints 13b with the upper and lower main girders 11 are welded from the inside of the concave recess. The joints 13a are formed with a predetermined weld length, alternating left and right along the vertical direction. This is to prevent distortion of the shape-retaining member 13. However, the joints 13a may be provided only on the right or left side of the shape-retaining member 13, eliminating the need for joining. The joints 13a may be provided continuously along the vertical direction or partially. Similarly, the joints 13b may be provided continuously along the radial direction of the drilling hole or partially.

The shape-retaining member 13 may be configured such that the joint 13a with the inner surface of the skin plate 10 is omitted, and only the joints 13b with the upper and lower main girders 11 are welded from the inside of the recess. In other words, it is not necessary to weld the shape-retaining member 13 to the skin plate 10. This is because the shape-retaining member 13 is not provided for the purpose of increasing the strength of the steel earth-retaining panel 1, but for the purpose of maintaining the shape of the steel earth-retaining panel 1 during its manufacture, transportation, and construction, and therefore minimal welding and fixing is sufficient. This reduces the effort and cost of welding work and increases productivity.

Figure 13 is an explanatory diagram showing modified example 1 of the shape retention member of the steel earth retaining panel according to the embodiment. The shape retention member 14 shown in Figure 13 is a rod-shaped member made of a reinforcing bar with an outer diameter of about 6 mm. A plurality of these shape retention members 14 are arranged at intervals in the arc direction. Only the joints 14b of the shape retention members 14 to the upper and lower main girders 11 are welded from the inside of the recess. The outer diameter and number of the shape retention members 14 to be arranged are determined taking into consideration, for example, the size and shape of the steel earth retaining panel 1.

Figure 14 is an explanatory diagram showing a modified example 2 of the shape retention member of the steel earth retaining panel according to the embodiment. The shape retention member 15 shown in Figure 14 is formed, for example, by combining two reinforcing bars 15a and 15b, and is configured to be provided between the upper and lower main girders 11. One end of one reinforcing bar 15a is fixed by welding to the upper main girder 11, and one end of the other reinforcing bar 15b is fixed by welding to the lower main girder 11. The other end of one reinforcing bar 15a and the other end of the other reinforcing bar 15b are fixed to each other by welding. The reason why the shape retention member 15 is composed of two reinforcing bars 15a and 15b is that the length is adjusted so that it fits between the upper and lower main girders 11 and is installed. The shape retention member 15 may be provided at a position spaced a predetermined distance from the inner surface of the skin plate 10 as shown in Figure 14, but may also be provided in a position close to the inner surface of the skin plate 10, for example. Furthermore, the shape-retaining member 15 is not limited to two reinforcing bars 15a and 15b, but may be made of, for example, two steel plates.

Next, an example of a construction method for the above-mentioned earth retaining structure 100 will be described with reference to Figures 15 and 16. Figure 15 is an explanatory diagram that shows a schematic diagram of an example of a construction method for an earth retaining structure according to an embodiment. Figure 16 is a plan cross-sectional view that shows an example of a first earth retaining structure part in an earth retaining structure according to an embodiment. The arrows in Figure 16 indicate the range of each steel earth retaining panel 1.

In the construction method for the earth retaining structure 100 according to this embodiment, after constructing the second earth retaining structure 102, the first earth retaining structure 101 is constructed below the second earth retaining structure 102. First, as shown in FIG. 15(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, the structure 102A is assembled by placing the corrugated steel plate 2 in a ring shape along the wall surface of the borehole 201.

The structure 102A is assembled by arranging the corrugated steel plates 2 in order along the circumferential direction of the wall surface of the borehole 201, and connecting adjacent corrugated steel plates 2 on the left and right with bolts and nuts. The corrugated steel plates 2 of the upper structure 102A and the corrugated steel plates 2 of the lower structure 102A are connected with bolts and nuts. The corrugated steel plates 2 of the upper structure 102A and the corrugated steel plates 2 of the lower structure 102A are arranged with their circumferential positions shifted so as to form a staggered arrangement. In this way, a part of the second retaining structure 102 is constructed by stacking the structures 102A in multiple layers (three layers in the illustrated example) along the hole axis direction.

Next, as shown in FIG. 15(B), the structure 102A located at the top is fixed to the ground 200 with a lattice 300, and then the excavation hole 201 outside the structure 102A is backfilled with excavated soil. Note that the means for fixing the structure 102A located at the top to the ground 200 is not limited to the lattice 300, and concrete may be used, for example.

As shown in FIG. 15(C), the ground is excavated while assembling the structures 102A and 101A to construct the second retaining structure 102 and the first retaining structure 101, and excavation is continued to a predetermined depth. After the structure 102A located at the top is fixed with the lattice 300, a corrugated steel plate 2 is placed at the bottom end of the structure 102A at the bottom along the circumferential direction of the wall surface of the excavation hole 201, and the corrugated steel plate 2 is connected to the corrugated steel plate 2 at the bottom 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 structure 102A. In addition, concrete or mortar is filled between the corrugated steel plate 2 and the excavation hole 201 as a backfill injection material.

As shown in FIG. 15(C), the first retaining structure 101 is constructed at the lower end of the second retaining structure 102 after the second retaining structure 102 is constructed. As shown in FIG. 16, the structure 101A is assembled by arranging the steel retaining panels 1 in order along the circumferential direction of the wall surface of the borehole 201. The steel retaining panels 1 arranged on the wall surface of the borehole 201 are connected to the upper corrugated steel plate 2 or the upper steel retaining panel 1 with bolts and nuts, and are connected to the adjacent steel retaining panels 1 on the left and right with bolts and nuts. The upper corrugated steel plate 2 or the upper steel retaining panel 1 and the lower steel retaining panel 1 are arranged with their circumferential positions shifted so as to be staggered. In this way, the first retaining structure 101 is constructed by stacking the structures 101A in a plurality of stages along the hole axis direction. In addition, concrete or mortar is filled between the steel earth retaining panel 1 and the excavation hole 201 as a backfill injection material. In addition, it is preferable that the steel earth retaining panel 1 placed last in the circumferential direction in each structure 101A has a length in the arc direction that is about 0 mm to 6 mm shorter than the other steel earth retaining panels 1, and more preferably about 3 mm shorter. This is to make it easier to insert the steel earth retaining panel 1 placed last into the space formed by the left and right steel earth retaining panels 1 that have already been placed, and to improve the workability of assembly.

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 structure 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 with a number other than six. Furthermore, the retaining structure 100 according to this embodiment is not limited to a configuration having the second retaining structure 102 constructed with corrugated steel plates 2 and the first retaining structure 101 constructed with steel retaining panels 1, and although not shown in the figure, it may be composed of only the first retaining structure 101 constructed with steel retaining panels 1.

Figure 17 is a plan cross-sectional view showing a modified example 1 of a steel earth retaining panel according to an embodiment. Figure 18 (A) is a front view of the steel earth retaining panel shown in Figure 17, and (B) is a left side view of the steel earth retaining panel. Figure 19 is a plan cross-sectional view showing an example of a first earth retaining structure part in an earth retaining structure using the steel earth retaining panel shown in Figure 17. Figure 20 is an enlarged view of part A shown in Figure 19. Figure 21 is an explanatory diagram showing a schematic diagram of the procedure for constructing the first earth retaining structure part of the earth retaining structure shown in Figure 19. Figure 22 is an explanatory diagram showing in detail the characteristics of the construction method of the earth retaining structure shown in Figure 19. Note that the numbers in parentheses shown in Figures 21 and 22 indicate the numbers of the pieces of the steel earth retaining panel 1A.

As shown in Figs. 17 and 18, the steel earth retaining panel 1A is arc-shaped in plan view, and both end faces in the arc direction are inclined relative to the radial direction of the excavation hole 201. Specifically, in plan view, the steel earth retaining panel 1A has both end portions in the arc direction of the main girder 11 and the joint plate 12 inclined relative to the radial direction of the excavation hole 201. In other words, as shown in Figs. 19 and 20, in a structure 101A constructed by arranging multiple steel earth retaining panels 1A in a ring shape, the pair of end faces where the steel earth retaining panels 1A adjacent in the circumferential direction butt against each other are inclined relative to the radial direction of the excavation hole 201. Incidentally, inclined relative to the radial direction of the excavation hole 201 means that the steel earth retaining panel 1A to be installed last is inclined to such an extent that it can be slid circumferentially from the inside of the structure 101A into the space formed between the already installed left and right steel earth retaining panels 1A and 1A.

To construct an earth retaining structure 100 using the steel earth retaining panels 1A shown in Figures 17 and 18, as shown in Figure 21 (A), the first to fifth pieces of steel earth retaining panels 1A 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 1A, to construct a part of the structure 101A. The first to fifth pieces of steel earth retaining panels 1A are connected to the upper corrugated steel plate 2 or the upper steel earth retaining panel 1A with bolts and nuts, and adjacent steel earth retaining panels 1A on the left and right are connected to each other with bolts and nuts.

21(B), the remaining sixth piece of steel earth retaining panel 1A is inserted into the space S formed between the first piece of steel earth retaining panel 1A and the fifth piece of steel earth retaining panel 1A by sliding it in the circumferential direction from the inside of the structure 101A. At this time, as shown in FIG. 22, one joint plate 12 of the sixth piece of steel earth retaining panel 1A is slid relative to one joint plate 12 of the fifth piece of steel earth retaining panel 1A. After one end of the sixth piece of steel earth retaining panel 1A is slid into the space S between the first piece of steel earth retaining panel 1A and the fifth piece of steel earth retaining panel 1A, as shown in FIG. 21(C) and FIG. 22, the other end of the sixth piece of steel earth retaining panel 1A is pushed from the inside of the structure 101A toward the outside (the direction of the arrow X in the figure) and fitted into the space S. Then, the sixth piece of steel retaining panel 1A is connected to the upper corrugated steel plate 2 or steel retaining panel 1A with bolts and nuts, and is also connected to the adjacent steel retaining panels 1A on the left and right with bolts and nuts.

The steel earth retaining panel 1A and the earth retaining structure 100 using the steel earth retaining panel 1A shown in Figures 17 and 18 use a steel earth retaining panel 1A that is arc-shaped when viewed from above and has both end faces in the arc direction that are inclined relative to the radial direction of the excavation hole 201. This allows the last steel earth retaining panel 1A to be installed to be slid circumferentially from the inside of the structure 101A into the space S formed between the left and right steel earth retaining panels 1A that have already been installed, improving workability.

The steel retaining panels 1A forming the structure 101A may be configured such that, as shown in FIG. 19, all pairs of end faces where adjacent steel retaining panels 1A in the circumferential direction butt together are inclined relative to the radial direction of the excavation hole 201, or, although not shown in the figure, at least one or more pairs may be configured to be inclined relative to the radial direction of the excavation hole 201.

Figure 23 is a plan view showing modified example 2 of the steel earth retaining panel according to the embodiment. Figure 24 is an enlarged view of the left side of the steel earth retaining panel shown in Figure 23. Figure 25 is an enlarged view showing a schematic of the main parts of the earth retaining structure using the steel earth retaining panel shown in Figure 23.

As shown in Figures 23 to 25, the upper and lower main girders 11 may be provided so that their outer edges 11c protrude toward the wall surface of the excavation hole 201 beyond the outer surface of the skin plate 10. The outer edges 11c here refer to the parts that protrude toward the wall surface of the excavation hole 201 beyond the outer surface of the skin plate 10. The protruding length of the outer edges 11c of the main girders 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 202 filled between the outer surface of the earth retaining structure 100 and the excavation hole 201 enters. In other words, the steel earth retaining panel 1B can form a fixing allowance for the backfill injection material 202 filled and hardened between the wall surface of the excavation hole 201 and the steel earth retaining panel 1B to be caught by the concave space S, thereby improving the fixing ability of the backfill injection material 202.

Although not shown in the figures, the steel retaining panel 1B 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 space can be formed on which the backfill injection material 202 filled and hardened between the wall surface of the excavation hole 201 and the steel retaining panel 1B can be caught, thereby improving the fixing property of the backfill injection material 202.

The features of the steel earth retaining panel 1B shown in Figures 23 to 25 are shown when applied to the shape of the steel earth retaining panel 1A shown in Figures 17 and 18, but can also be applied to the shape of the steel earth retaining panel 1 shown in Figures 6 to 8.

Figure 26 is a perspective view showing a modified example of an earth retaining structure according to the embodiment. Figure 27 is a perspective view showing a modified example of a steel earth retaining panel according to the embodiment.

The earth retaining structure 100 according to this embodiment is not limited to the circular shape in plan view shown in FIG. 1. The earth retaining structure 100 may be constructed in a rectangular shape in plan view by installing a corrugated steel plate 2 and a steel earth retaining panel 1C in a vertical excavation hole formed by excavating the ground, as shown in FIG. 26. Specifically, the earth retaining structure 100 has a second earth retaining structure 102 constructed by stacking four structures 102A formed by arranging the corrugated steel plate 2 in a rectangular shape in plan view in the hole axis direction, and a first earth retaining structure 101 constructed by stacking two structures 101A formed by arranging the steel earth retaining panels 1C in a rectangular shape in plan view in the hole axis direction. The second earth retaining structure 102 is assembled by arranging the corrugated steel plate 2 in a staggered manner. The first earth retaining structure 101 is also assembled by arranging the steel earth retaining panels 1 in a staggered manner. The corrugated steel plate 2 shown in FIG. 26 uses the plank plate 2B shown in FIG. 4 and FIG. 5, but the liner plate 2A shown in FIG. 2 and FIG. 3 may also be used. 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. Also, the number of corrugated steel plates 2 and steel retaining panels 1C that make up each structure 102A and 101A shown in FIG. 26 is one example.

As shown in FIG. 27, the steel earth retaining panel 1C has a flat skin plate 10 facing the wall of the excavation hole, flat main girders 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 left and right ends of the skin plate 10 to form the left and right side surfaces. The steel earth retaining panel 1C is configured to be concave and open toward the inside of the excavation hole 201. The skin plate 10, main girders 11, and joint plates 12 are each fixed by welding. Although not shown enlarged, an L-shaped steel earth retaining panel 1C for the corner portion is placed at the rectangular corner of the first earth retaining structure 101 shown in FIG. 26.

In this way, the retaining structure 100 according to this embodiment can be constructed in various shapes by modifying the shape of the corrugated steel plate 2 and the steel retaining panel 1C. The retaining structure 100 is not limited to the circular shape shown in FIG. 1 and the rectangular shape shown in FIG. 26, but may be, for example, an oval shape like an oval coin in plan view, or a U-shape like a horseshoe. The corrugated steel plate 2 and the steel retaining panel 1C are configured in a shape that corresponds to the shape of the retaining structure 100.

As described above, the steel earth retaining panel 1 according to this embodiment includes a skin plate 10 facing the wall surface of the excavation hole 201, a main girder 11 provided at the upper and lower ends of the skin plate 10 to form the upper and lower surfaces, and a joint plate 12 provided at both the left and right ends of the skin plate 10 to form the left and right side surfaces. The steel earth retaining panel 1 is formed in a concave shape that opens toward the inside of the excavation hole 201, and either or both of the joint portion 10a between the skin plate 10 and the main girder 11 and the joint portion 10b between the skin plate 10 and the joint plate 12 are welded and joined from the inside of the concave shape. Therefore, the steel earth retaining panel 1 according to this embodiment can omit part or all of the welding work from the outer surface side of the steel earth retaining panel 1, thereby improving the work efficiency of the welding work and reducing the manufacturing effort and cost.

The joint 10c between the main girder 11 and the joint plate 12 is welded from the inside of the concave shape. Therefore, the steel retaining panel 1 according to this embodiment can omit some or all of the welding work from the outer surface side of the steel retaining panel 1, which can increase the efficiency of the welding work and reduce the manufacturing effort and cost.

The steel earth retaining panel 1 is also provided with a shape retaining member 13 that is provided between the upper and lower main girders 11 and that maintains the concave shape. Therefore, in the steel earth retaining panel 1 according to this embodiment and the earth retaining structure 100 that uses the steel earth retaining panel 1, the shape of the steel earth retaining panel 1 can be maintained during manufacturing, transportation, and construction, improving workability and contributing to shortening the construction period.

The shape-retaining members 13 are plate- or rod-shaped members, and are welded and fixed only to the main girder 11. This is because the shape-retaining members 13 are not provided for the purpose of increasing the strength of the steel earth-retaining panel 1, but for the purpose of maintaining the shape of the steel earth-retaining panel 1 during its manufacture, transportation, and construction, and therefore minimal welding and fixing is sufficient. Therefore, the steel earth-retaining panel 1 of this embodiment can reduce the effort and cost of welding work and increase productivity.

The shape-retaining member 15 is formed by combining two members 15a and 15b. One end of the member 15a is fixed to one main girder 11, and one end of the member 15b is fixed to the other main girder 11, and the other ends of the member 15a and the member 15b are fixed to each other, and the shape-retaining member 15 is provided between the upper and lower main girders 11. In other words, the length of the shape-retaining member 15 can be adjusted and installed so that it fits between the upper and lower main girders 11. Therefore, the steel earth-retaining panel 1 according to this embodiment can contribute to improving the workability of the earth-retaining structure 100.

Although the steel earth retaining panels (1, 1A, 1B, 1C) and the earth retaining structure 100 have been described above based on the embodiment, the steel earth retaining panels (1, 1A, 1B, 1C) and the earth retaining structure 100 are 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. 15 is one example and is not limited to the above-mentioned embodiment. In addition, the shape retaining members (13, 14, 15) are not limited to the configuration shown in the figure, and any member may be used and any configuration may be used as long as the shape of the steel earth retaining panel 1 can be maintained. In short, the steel earth retaining panels (1, 1A, 1B, 1C) and the earth 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 of their technical concept.

1, 1A, 1B, 1C Steel retaining panel, 2 Corrugated steel plate, 2A Liner plate, 2B Plank plate, 10 Skin plate, 10a, 10b, 10c Joint, 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, 13a, 13b Joint, 14 Shape retaining member, 14b Joint, 15 Shape retaining member, 15a, 15b Reinforcement bar (member), 20 Circumferential flange, 20a Connection hole, 21 Axial flange, 21a Connection hole, 100 Retaining structure, 101 First retaining structure, 101A Structure, 102 Second retaining structure, 102A Structure, 200 Ground, 201 borehole, 202 backfill injection material, 300 grid, S space.

Claims (5)

A steel earth retaining panel used to construct an earth retaining structure by being installed in a borehole formed by excavating the ground,
A skin plate facing a wall surface of the borehole;
A main girder provided at the upper end and the lower end of the skin plate and forming an upper surface and a lower surface;
A joint plate is provided at both left and right ends of the skin plate to form left and right side surfaces,
The borehole is formed in a concave shape that opens toward the inside of the borehole, and one or both of the joint between the skin plate and the main girder and the joint between the skin plate and the joint plate are welded and joined from the concave inner side of the concave shape ,
Further, a shape retention member is provided between the upper and lower main beams and retains the concave shape,
The joint between the shape-retaining member and the skin plate is configured to be joined by welding from the concave inner side of the concave shape,
A steel retaining panel, in which the joints between the shape retention member and the skin plate are formed alternately left and right along the vertical direction. The steel retaining panel according to claim 1, in which the joint between the main girder and the joint plate is welded from the inside of the recess. The shape retention member is formed by combining two members, one end of one member is fixed to one main girder and one end of the other member is fixed to the other main girder, and the other ends of the one member and the other member are fixed to each other, and the shape retention member is disposed between a pair of the main girders.A steel earth retaining panel as described in claim 1 or 2 . A retaining structure constructed by installing a plurality of steel retaining panels in a borehole formed by excavating the ground,
A structure formed by arranging a plurality of the steel earth retaining panels 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 the plurality of steel retaining panels include at least one steel retaining panel according to any one of claims 1 to 3 . A structure formed by arranging a plurality of corrugated steel plates along the wall surface of the borehole further includes a second retaining structure constructed in at least one stage in the hole axial direction,
The earth retaining structure according to claim 4 , wherein the first earth retaining structural portion is constructed below the second earth retaining structural portion.

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