Steel support worker

Abstract

To provide a steel support that can tolerate a deformation to some extent without largely protruding to inside of a tunnel when pressure is applied to circumference of an excavation surface from foundation and allows lining work to be smoothly executed.SOLUTION: A steel support 16 supports an excavation surface 12 in collaboration with a spraying concrete 14. The steel support 16 has a support 20 extending along the excavation surface 12. The support 20 is configured by connecting a plurality of steel support members 22. A compression coil spring 26 and a cover 28 covering the compression coil spring 26 are disposed between adjacent steel support members 22. The compression coil spring 26 is compressed and deformed before the support 20 deforms when load from the excavation surface 12 is applied to the steel support member 22.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a steel support used for NATM construction. [Background technology]

[0002] In tunnels excavated using NATM, concrete is sprayed as a primary spray onto the excavated surface of the tunnel, which has been dug into the ground using blasting and drilling equipment. Steel supports are then assembled along this concrete, and concrete is sprayed on top of the concrete and steel supports as a secondary spray. Finally, support is provided by driving multiple rock bolts into the ground on top of the concrete. The excavated surface is supported by steel supports, sprayed concrete, and rock bolts to prevent the excavated surface from collapsing. Depending on the geology of the ground, either the steel supports or the rock bolts may be omitted. After that, once the ground around the excavation surface has stabilized, the lining is done by pouring concrete using a slide centre over steel supports, sprayed concrete and rock bolts. In this way, NATM has the advantage that the thickness of the concrete lining can be reduced, as it uses steel supports, shotcrete, and rock bolts to support the excavation surface while preventing it from collapsing and stabilizes the ground surrounding the excavation surface. On the other hand, in NATM, when pressure from the surrounding ground acts on the excavation surface, it is desirable for the steel support to be allowed to deform to a certain extent and absorb the deformation of the ground in order to stabilize the ground surrounding the excavation surface. From this perspective, a technique has been disclosed that allows deformation of steel support members constituting a steel support (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6584738 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional technology, a concrete body is used in which concrete is sprayed onto a synthetic resin framework structure. When pressure from the ground acts around the excavation surface, the concrete is compressed and protrudes significantly into the inside of the tunnel, making it difficult to carry out the lining work smoothly and causing problems in the lining work. The present invention has been made in consideration of the above circumstances, and its purpose is to provide a steel support that can tolerate a certain degree of deformation in the support without protruding significantly into the inside of the tunnel when pressure from the ground acts around the excavation surface, allowing lining work to be carried out more smoothly than with the above-mentioned conventional techniques, shortening the construction period for tunnel construction, and being advantageous in reducing costs. [Means for solving the problem]

[0005] In order to achieve the above-mentioned object, one embodiment of the present invention is a steel support assembled along the excavation surface of an excavated tunnel to support the excavation surface in cooperation with sprayed concrete sprayed onto the excavated surface, the steel support including a support structure formed by connecting a plurality of steel support members extending along the excavation surface in a plane perpendicular to the excavation direction of the tunnel, and characterized in that compression coil springs are arranged at a plurality of locations spaced apart in the extension direction of the support structure, which undergo compressive deformation prior to deformation of the steel support members when a load from the excavation surface acts on the support structure. In addition, one embodiment of the present invention is characterized in that the compression coil spring is interposed between adjacent steel support members in the extension direction of the support structure. In addition, one embodiment of the present invention is characterized in that the compression coil spring is interposed between the adjacent steel support members via a pair of spring mounting plates, and the spring mounting plates include a spring support plate portion having one surface that serves as a spring support surface against which the axial end of the compression coil spring abuts, and a support member mounting plate portion that is attached to the steel support member. In addition, one embodiment of the present invention is characterized in that a positioning pin to be inserted into the compression coil spring is protruded from the spring receiving surface of the spring receiving plate against which the end of the compression coil spring abuts. In one embodiment of the present invention, a compressible and deformable cover is provided to cover the compression coil spring. In one embodiment of the present invention, the cover is provided across the spring receiving plate portions of the pair of spring mounting plates. In addition, one embodiment of the present invention is characterized in that the ends of the compression coil spring are attached to the spring receiving surface with the ends abutting the spring receiving surface, and the compression coil spring, the cover, and the spring receiving plate portions of the pair of spring mounting plates are integrated together. Effect of the Invention

[0006] According to one embodiment of the present invention, when a load from the ground acts on the support from the excavation surface, causing an axial compressive force on the support, the compression coil spring undergoes compressive deformation prior to deformation of the support, absorbing the deformation of the ground and stabilizing the ground around the tunnel. In this case, since the compression coil spring undergoes compression deformation, it does not protrude significantly into the inside of the tunnel as in the above-mentioned prior art. Therefore, when loads from the surrounding ground act on the excavation surface, the steel supports are allowed to deform to a certain extent, absorbing the deformation of the ground and stabilizing it, and since they do not protrude significantly into the inside of the tunnel as in the conventional technology described above, lining work can be carried out more smoothly than with the conventional technology described above, which is advantageous in shortening the construction period for tunnel construction and reducing costs. Furthermore, according to one embodiment of the present invention, the compression coil spring is interposed between adjacent steel support members in the extension direction of the support, so that the installation of the compression coil spring can be easily performed, which is advantageous in shortening the construction period of tunnel construction and reducing costs compared to the conventional technology described above. Furthermore, according to one embodiment of the present invention, a pair of spring mounting plates include a spring receiving plate portion and a support member mounting plate portion that is attached to a steel support member, making it easy to install the compression coil springs, which is advantageous in shortening the construction period of tunnel construction and reducing costs compared to the conventional technology described above. In addition, since a positioning pin for positioning the compression coil spring is provided on the spring receiving surface of the spring receiving plate, this is advantageous in that the compression coil spring can be smoothly and reliably compressed and deformed prior to deformation of the steel support member, allowing lining work to be carried out more smoothly than with the conventional technology described above, and is advantageous in shortening the construction period for tunnel construction and reducing costs. Furthermore, providing a cover is advantageous in terms of efficient concrete spraying. Furthermore, providing the cover on the spring receiving plate portion is advantageous in integrating the compression coil spring, the cover, and the spring receiving plate portions of the pair of spring mounting plates. In addition, when the end of the compression coil spring is attached to the spring receiving surface, the compression coil spring, cover, and pair of spring mounting plates are integrated, making it easy to handle the compression coil spring and cover, which is advantageous in shortening the construction period for tunnel construction and reducing costs compared to the conventional technology described above. [Brief description of the drawings]

[0007] [Figure 1] This is an explanatory diagram of the steel supports, sprayed concrete, and rock bolts that support the excavation surface. [Diagram 2] This is a front view of the support structure. [Diagram 3] 1 is an explanatory diagram of the excavation surface, the primary sprayed concrete, and the H-shaped steel that constitutes the steel support member. [Figure 4] FIG. 4 is an explanatory diagram of the positional relationship between a steel support member and a compression coil spring. [Diagram 5] (A) A view of the steel support member, compression coil spring, and cover from the center of the tunnel cross section, and (B) a view of the steel support member, compression coil spring, and cover from the direction of tunnel excavation, with the cover shown in cross section. [Figure 6] 1A is a plan view of a spring mounting plate, FIG. 1B is a partially sectional front view of the spring mounting plate, and FIG. [Figure 7] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, at a portion of the tunnel 10 near the face, the tunnel 10 is excavated using blasting or drilling equipment, and concrete 14A is sprayed onto the excavated surface 12 of the tunnel 10 as a primary spraying, and a steel support 16 is assembled in an arch shape along the surface of the concrete 14A. Then, a secondary sprayed concrete 14B is sprayed from above the primary sprayed concrete 14A and the steel support 16 to near the surface of the steel support 16, and further, a plurality of rock bolts 18 are driven into the ground around the tunnel 10 from above the secondary sprayed concrete 14B. In NATM, such steel supports 16, sprayed concrete 14, and rock bolts 18 are used to support the excavation surface 12 while preventing the excavation surface 12 from collapsing, and to stabilize the ground around the excavation surface 12. Depending on the geology of the ground, the rock bolts 18 may be omitted, and the present invention is of course applicable in that case as well. Then, once the ground around the excavation surface 12 has stabilized, lining is done by pouring concrete over the steel supports 16, sprayed concrete 14, and rock bolts 18 using a slide center.

[0009] The steel support 16 is configured to include a plurality of supports 20 shown in FIG. 2 that are provided at intervals in the excavation direction X of the tunnel 10 (see FIGS. 3 and 4). The support structure 20 extends in an arch shape along the circumferential direction of the tunnel cross section obtained by cutting the tunnel 10 in a plane perpendicular to the excavation direction X of the tunnel 10, and connecting materials (not shown) extend in the excavation direction X of the tunnel 10 and connect multiple points of adjacent supports 20.

[0010] As shown in FIGS. 2 and 5, the support 20 is configured to include a plurality of steel support members 22, a plurality of compression coil springs 26, and a cover 28 that covers the periphery of each compression coil spring 26. The steel support member 22 is made of structural steel, and in this embodiment, the steel support member 22 is made of an H-shaped steel consisting of a pair of flanges 2402 and a web 2404 connecting the flanges 2402, as shown in Figure 3. The H-shaped steel that constitutes the steel support member 22 is arranged with a pair of flanges 2402 facing approximately the center of the tunnel cross section obtained by cutting the tunnel 10 on a plane perpendicular to the excavation direction X of the tunnel 10, and with the web 2404 facing the excavation direction X of the tunnel 10.

[0011] As shown in Figs. 2 and 5, the compression coil springs 26 and covers 28 are provided at a plurality of locations spaced apart in the extension direction of the support 20. When the load from the ground acts on the support 20 from the excavation surface 12 and axial compressive force is generated in the support 20 in order for the support 20 to maintain its arch shape, the compression coil spring 26 undergoes compressive deformation prior to deformation of the steel support member 22. In other words, when a compressive stress that deforms the steel support member 22 acts on the compression coil spring 26, the compression spring 26 undergoes compressive deformation prior to deformation of the steel support member 22. In detail, when the compressive stress generated in the support structure 20 is sufficiently smaller than the stress that deforms the steel support member 22, the compression coil spring 26 does not undergo compressive deformation and maintains its free length, and when the compressive stress approaches the stress that deforms the steel support member 22, the compression coil spring 26 undergoes compressive deformation from its free length. From this perspective, the material, wire diameter, outer diameter, number of turns, etc., constituting the compression coil spring 26 are set, and in this embodiment, as shown in FIG. 4, it is formed with an outer diameter that fits inside the outline of the cross-sectional shape of the H-shaped steel.

[0012] The cover 28 is a member that prevents concrete 14B from being sprayed onto the compression coil spring 26 as a secondary spray so that the compression coil spring 26 can be smoothly compressed and deformed. More specifically, the cover 28 is a member that prevents the compression coil spring 26 from being prevented from being compressed and deformed by spraying and filling the outer periphery or interior of the compression coil spring 26 with concrete 14B as a secondary spray. Incidentally, when spraying the concrete 14B, the cover 28 can be omitted by spraying the concrete 14B onto the concrete 14A so that the concrete 14B is not sprayed onto the compression coil spring 26. However, providing the cover 28 as in this embodiment is advantageous in terms of efficient spraying of the concrete 14B. The total length of the multiple compression coil springs 26 and covers 28 installed on the support 20 is approximately 10% of the total length of the support 20, and the length of one compression coil spring 26 and cover 28 is approximately a few percent of the total length of the support 20.

[0013] The compression coil springs 26 are interposed between adjacent steel support members 22 via a pair of spring mounting plates 30 . The compression coil spring 26 is arranged via a pair of spring mounting plates 30 with its axis aligned along the extension direction of the support structure 20, and as shown in Figure 4, its axis is aligned with the centroid of the H-shaped steel that constitutes the steel support member 22 so that it can be smoothly compressed and deformed by the load from the steel support member 22. As shown in FIG. 6, the spring attachment plate 30 includes a spring receiving plate portion 3002 and a support member attachment plate portion 3004. The spring receiving plate portion 3002 is a spring support member attachment plate portion 3004. As shown in FIG. As shown in FIGS. 6(A), 5(A) and (B), the spring receiving plate portion 3002 has a rectangular shape with a contour larger than the outer diameter of the compression coil spring 26. One surface of the spring support plate portion 3002 is formed as a spring support surface 3012 against which the end of the compression coil spring 26 abuts, and the other surface is formed as a support member support surface 3014 against which the end of the steel support member 22 abuts.

[0014] A positioning pin 3022 is protruded from the spring receiving surface 3012 and is inserted into the compression coil spring 26 to position the compression coil spring 26 relative to the spring receiving surface 3012 . As shown in Figures 5(A) and (B), the end of the compression coil spring 26 is abutted against the spring receiving surface 3012 with the positioning pin 3022 inserted therein, and is attached to the spring receiving surface 3012 via a fastener (not shown) or by welding, and when attached in this manner, the compression coil spring 26 has a free length. Therefore, the compression coil spring 26 and the pair of spring mounting plates 30 are integrated together.

[0015] The support member mounting plate portions 3004 are provided in pair, protruding from both sides of the support member receiving surface 3014 of the spring receiving plate portion 3002 . The dimension between the pair of support member mounting plate portions 3004 is formed to allow a pair of flanges 2402 of the H-shaped steel constituting the steel support member 22 to be inserted therebetween. Each support member mounting plate portion 3004 is provided with two bolt insertion holes H1 spaced apart from one another. is. As shown in Figure 5, the ends of adjacent steel support members 22 abut against the support member receiving surfaces 3014 of the spring receiving plate portions 3002 of a pair of spring mounting plates 30, a pair of support member mounting plate portions 3004 are fitted to the H-shaped steel flanges 2402 at the ends of the steel support members 22, and the pair of spring mounting plates 30 are attached to the ends of adjacent steel support members 22 by bolts B1 inserted into the bolt insertion holes H1 and screwed into the female threads F1 of the flanges 2402. In addition, a pair of spring mounting plates 30 for mounting the compression coil spring 26 to the steel support member 22 may be composed of, for example, a flat plate attached by welding to the ends of adjacent steel support members 22 and a flat plate attached to both longitudinal ends of the compression coil spring 26, and the flat plates attached to the ends of the steel support members 22 and the flat plates attached to the ends of the compression coil spring 26 may be fastened with bolts and nuts. Various conventionally known configurations can be adopted for the configuration for mounting the compression coil spring between the ends of adjacent steel support members 22, and are not limited to the configuration of the embodiment. However, the configuration as in the embodiment is advantageous in that the compression coil spring can be easily and reliably mounted between the ends of adjacent steel support members 22.

[0016] The cover 28 is provided between the spring receiving plate portions 3002 of the pair of spring mounting plates 30, and covers the periphery of the compression coil spring 26. In this embodiment, both axial ends of the compression coil spring 26 are covered by spring receiving plates 3002, and the outer periphery of the compression coil spring 26 is covered by a cover 28. The cover 28 is made of an elastic material such as rubber so that the compression coil spring 26 can be smoothly compressed and deformed, and is deformable in the axial direction of the compression coil spring 26. Any cover 28 may be used, such as a bellows-shaped cover made of a metal plate, a synthetic resin plate, or the like, so long as the compression coil spring 26 can be smoothly compressed and deformed. As shown in FIG. 7, in this embodiment, the cover 28 is formed to extend in a rectangular tubular shape or in a bellows shape. The compression coil spring 26 is inserted inside the cover 28, and both ends of the cover 28 in the extending direction are covered by the spring receiving plate portion 3002 and are bonded to the spring receiving plate portion 3002 with an adhesive. Therefore, the compression coil spring 26, the cover 28, and the pair of spring receiving plate portions 3002 are integrated together; in other words, the compression coil spring 26, the cover 28, and the pair of spring mounting plates 30 are integrated together, which makes it easy to handle and improves the efficiency of the work of connecting the compression coil spring 26 and the cover 28 to the steel support member 22. The covers 28 may be directly attached to the ends of the adjacent steel support members 22, and the arrangement of the covers 28 is not limited to the configuration of the embodiment. However, the configuration of the embodiment is advantageous in that it is easy to handle and improves the efficiency of the work of connecting the compression coil springs 26 and the covers 28 to the steel support members 22.

[0017] According to this embodiment, when a load from the ground acts on the support 20 from the excavation surface 12 and an axial compressive force is generated in the support 20, the compression coil spring 26 undergoes compressive deformation prior to deformation of the steel support member 22. The compression deformation of the compression coil spring 26 absorbs deformation of the ground (displacement of the excavation surface) and stabilizes the ground around the tunnel 10. In this case, since the compression coil spring 26 is compressed and deformed, it does not protrude significantly into the inside of the tunnel 10 as in the above-mentioned conventional technology. Therefore, according to this embodiment, when a load from the surrounding ground acts on the excavation surface 12, the deformation of the ground can be absorbed by allowing the steel support 16 to deform to a certain extent, and the ground can be stabilized. Since the steel support 16 does not protrude significantly into the inside of the tunnel 10 as in the above-mentioned conventional technology, the lining work can be carried out more smoothly than in the above-mentioned conventional technology, which is advantageous in shortening the construction period of the tunnel construction and reducing costs.

[0018] In addition, since the compression coil spring 26 and the cover 28 are interposed between adjacent steel support members 22 in the extension direction of the support structure 20, the arrangement of the compression coil spring 26 and the cover 28 can be easily carried out, which is advantageous in shortening the construction period of tunnel construction and reducing costs compared to the conventional technology described above. In addition, the pair of spring mounting plates 30 are equipped with a spring receiving plate portion 3002 against which the axial end of the compression coil spring 26 and the end of the steel support member 22 abut, and a support member mounting plate portion 3004 which is attached to the steel support member 22, and the cover 28 is provided between the pair of spring mounting plates 30, so that the arrangement of the compression coil spring 26 and the cover 28 can be easily carried out, which is advantageous in terms of shortening the construction period of tunnel construction and reducing costs compared to the above-mentioned conventional technology.

[0019] Furthermore, a positioning pin 3022 is provided on the spring receiving surface 3012 of the spring receiving plate portion 3002 so as to be inserted into the end of the compression coil spring 26 to position the compression coil spring 26 relative to the spring receiving surface 3012. This is advantageous in that the compression coil spring 26 can be smoothly and reliably compressed and deformed prior to deformation of the steel support member 22, and therefore lining work can be carried out more smoothly than with the above-mentioned conventional technology, which is advantageous in shortening the construction period for tunnel construction and reducing costs. In addition, since the end of the compression coil spring 26 is attached to the spring receiving surface 3012, and the compression coil spring 26, cover 28, and pair of spring mounting plates 30 are integrated, the compression coil spring 26 and cover 28 can be easily handled, which is advantageous in shortening the construction period of tunnel construction and reducing costs compared to the conventional technology described above. [Explanation of symbols]

[0020] 10. Tunnel 12 Excavation Surface 14. Shotcrete 14A Primary shotcrete 14B Secondary shotcrete 16 Steel shoring 18 Rock Bolt 20 Shoring 22 Steel support members 2402 Flange 2404 Web 26 Compression coil spring 28 Cover 30 Spring mounting plate 3002 Spring receiving plate 3004 Support member mounting plate 3012 Spring receiving surface 3014 Support member receiving surface 3022 Locating pin B1 Bolt F1 Female thread H1 Bolt insertion hole

Claims

1. A steel support structure assembled along an excavation surface of an excavated tunnel to support the excavation surface in cooperation with sprayed concrete sprayed on the excavation surface, The steel support includes a support structure formed by connecting a plurality of steel support members extending along the excavation surface in a plane perpendicular to the excavation direction of the tunnel, Compression coil springs are arranged at intervals in the extension direction of the support structure, and when a load from the excavation surface acts on the support structure, the compression coil springs are compressed and deformed prior to deformation of the steel support member, The compression coil spring is interposed between adjacent steel support members in the extension direction of the support via a pair of spring mounting plates, the spring mounting plate includes a spring receiving plate portion having one surface that serves as a spring receiving surface against which an axial end of the compression coil spring abuts, and a support member mounting plate portion that is attached to the steel support member, a positioning pin to be inserted into the compression coil spring is provided on a spring receiving surface of the spring receiving plate portion against which an end of the compression coil spring abuts; A steel support structure characterized by:

2. A compressible and deformable cover is provided to cover the compression coil spring.

2. The steel support according to claim 1.

3. The cover is provided between the spring receiving plate portions of the pair of spring mounting plates.

3. The steel support according to claim 2.

4. The end of the compression coil spring is attached to the spring receiving surface with the end of the compression coil spring abutting against the spring receiving surface, and the compression coil spring, the cover, and the spring receiving plate portions of the pair of spring mounting plates are integrated together.

4. The steel support according to claim 3.

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