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 sprayed on the excavation surface 12 and a plurality of rock bolts 18 driven in the excavation surface 12 from a surface of the spraying concrete 14. The steel support 16 includes a support 20 configured by connecting a plurality of steel support members 22. A steel deformation induction member 26A that more easily deforms than the steel support member 22 is disposed at a plurality of positions at intervals in extending direction of the support 20.SELECTED DRAWING: Figure 2

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 then sprayed onto 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 structure 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 structure 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 steel deformation-inducing members which are more easily deformed than the steel support members are arranged at a plurality of locations spaced apart in the extension direction of the support structure. In addition, one embodiment of the present invention is characterized in that the length, cross-sectional shape, or section modulus of the steel deformation inducing member along the extension direction of the support, or the material constituting the steel deformation inducing member, are set taking into account the amount of deformation of the steel deformation inducing member when a load from the ground acts on the support from the excavation surface. In addition, one embodiment of the present invention is characterized in that the steel support member and the steel deformation inducing member are constructed from the same structural steel, and the steel support member and the steel deformation inducing member are arranged with the cross-sectional shape of the structural steel being oriented in a different direction relative to the excavation direction of the tunnel. In addition, one embodiment of the present invention is characterized in that the steel support member and the steel deformation inducing member are both composed of the same H-shaped steel consisting of a pair of flanges and a web connecting the flanges, the H-shaped steel constituting the steel support member is positioned with the web facing the excavation direction of the tunnel, and the H-shaped steel constituting the steel deformation inducing member is positioned with the web facing the center of the tunnel cross section. In addition, one embodiment of the present invention is characterized in that the steel support member and the steel deformation inducing member are made of shaped steel having different shapes. In addition, one embodiment of the present invention is characterized in that the steel support member is composed of an H-shaped steel consisting of a pair of flanges and a web connecting the flanges, the H-shaped steel is arranged with the web facing the excavation direction of the tunnel, and the steel deformation inducing member is composed of a channel steel consisting of a web and a pair of flanges standing up from both ends of the web, and the channel steel is arranged with the web facing the center of the tunnel cross section. In addition, one embodiment of the present invention is characterized in that the steel support member is made of structural steel, and the steel deformation inducing member is made of reinforcing bar. In addition, one embodiment of the present invention is characterized in that the section modulus of the steel deformation inducing member is smaller than the section modulus of the steel support member. In addition, one embodiment of the present invention is characterized in that the steel deformation inducing member is formed of a material that is more easily deformed than the steel support member. In addition, one embodiment of the present invention is characterized in that the steel support member and the steel deformation inducing member are connected via a connecting member. Effect of the Invention

[0006] According to one embodiment of the present invention, when a load from the ground surrounding the tunnel acts on the excavation surface, the steel deformation inducing members deform prior to the steel support members, thereby absorbing the deformation of the ground and stabilizing the ground around the tunnel. In this case, since the steel deformation inducing member is a steel member and the amount of deformation can be adjusted, it does not protrude significantly into the inside of the tunnel as in the conventional case. Therefore, when loads from the surrounding ground act on the excavation surface, the steel supports can be allowed to deform to a certain extent to stabilize the ground, 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. The amount of deformation of the steel deformation inducing member can be adjusted by appropriately setting its length, cross-sectional shape, section modulus, and material. Furthermore, even if the same steel section is used for both the steel support members and the steel deformation inducing members, the cross-sectional shape of the steel section can be changed in accordance with the excavation direction of the tunnel, which is advantageous in terms of reducing costs. Furthermore, if H-shaped steel beams that make up the steel support members are used as the steel deformation-inducing members, the steel deformation-inducing members can be manufactured at the same time as the steel support members, which is advantageous in shortening the construction period for tunnel construction and reducing costs compared to the conventional technology mentioned above. Furthermore, if the steel support members and the steel deformation-inducing members are made from shaped steel beams with different shapes, they can be easily obtained as commercially available products, and the steel support members and the steel deformation-inducing members can be easily manufactured, which is advantageous in shortening the construction period of tunnel construction and reducing costs compared to the conventional technology described above. Furthermore, when the steel support member and the steel deformation-inducing member are constructed from shaped steel beams with different shapes, using H-shaped steel beams as the steel support member and channel steel beams as the steel deformation-inducing member is advantageous in easily manufacturing the steel support member and the steel deformation-inducing member, as these are easily available. In addition, using structural steel as the steel support member and reinforcing bar as the steel deformation inducing member is advantageous in easily manufacturing the steel support member and the steel deformation inducing member, since these are easily available. In addition, the steel deformation inducing member can be advantageously easily manufactured by using a steel member having a smaller section modulus than the steel support member, or by using a material that is more easily deformed than the steel support member. In addition, the steel support member and the steel deformation inducing member can be connected using a connecting member, and the connecting member can be a simple member such as a plate or bracket, which allows for a secure connection. [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] FIG. 1 is a front view of the steel support structure. [Diagram 3] (A) is an explanatory diagram of the excavation surface, the primary sprayed concrete, and the H-shaped steel that constitutes the steel support member of the first embodiment, and (B) is an explanatory diagram of the excavation surface, the primary sprayed concrete, and the H-shaped steel that constitutes the steel deformation inducing member of the first embodiment. [Figure 4] 4 is an explanatory diagram of the positional relationship between a steel support member and a steel deformation inducing member in the first embodiment. FIG. [Diagram 5] 1A is a view from the tunnel excavation direction showing the state in which the steel support member and the steel deformation inducing member of the first embodiment are connected by a plate, and FIG. 1B is a cross-sectional view of FIG. [Figure 6] FIG. 1 is an explanatory diagram of a steel support member and a steel deformation inducing member which are connected using a bracket instead of the plate in the first embodiment, where (A) is a view of the steel support member and the steel deformation inducing member from the center of the tunnel cross section, and (B) is a view of the steel support member and the steel deformation inducing member from the direction of excavation of the tunnel. [Figure 7](A) is a cross-sectional view of the steel support member and the steel deformation induction member connected by a bracket from the center of the tunnel cross section, and (B) is a view of the steel support member and the steel deformation induction member connected by a bracket from the direction of excavation of the tunnel. [Figure 8] 1A is a cross-sectional side view of the bracket, and FIG. 1B is a front view of the bracket. [Figure 9] FIG. 13 is an explanatory diagram showing the sealing of the gap between the steel deformation inducing member and the primary sprayed concrete. [Figure 10] 13 is an explanatory diagram of the positional relationship between a steel support member and a steel deformation inducing member in the second embodiment. FIG. [Figure 11] (A) is a cross-sectional view seen from the center of the tunnel cross section, showing the state in which a steel support member and a steel deformation inducing member of the second embodiment are connected by a bracket, and (B) is a view seen from the excavation direction of the tunnel, showing the state in which a steel support member and a steel deformation inducing member of the second embodiment are connected by a bracket. [Figure 12] 10A is a side view of a bracket according to a second embodiment, FIG. 10B is a front view of the bracket, and FIG. [Figure 13] 13 is an explanatory diagram of the positional relationship between a steel support member and a steel deformation inducing member in the third embodiment. FIG. [Figure 14] (A) is a cross-sectional view taken from the center of the tunnel cross section, showing the state in which a steel support member and a steel deformation inducing member of the third embodiment are connected by a bracket, and (B) is a view taken from the excavation direction of the tunnel, showing the state in which a steel support member and a steel deformation inducing member of the third embodiment are connected by a bracket. [Figure 15] 13A is a plan view of a bracket according to a third embodiment, FIG. 13B is a partially sectional front view of the bracket, and FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] (First embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. As shown in Figure 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 this primary sprayed concrete 14A. Then, concrete 14B is sprayed as a secondary spray onto the primary sprayed concrete 14A up to near the surface of the steel support structure 16, and a number 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 FIG. 2, the support 20 includes a plurality of steel support members 22 and a plurality of steel deformation inducing members 26A. 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 (A). In this embodiment, the dimension between the outer surfaces of the pair of flanges 2402 and the width of the flanges 2402 are set to the same value. 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 FIG. 2, the steel deformation inducing members 26A are provided at a plurality of locations spaced apart in the extension direction of the support 20. The steel deformation inducing member 26A is a steel member that deforms prior to the steel support member 22 when the load of the ground from the excavation surface 12 acts on the support 20. The total length of the multiple steel deformation inducing members 26A installed on the support 20 is approximately 10% of the total length of the support 20, and the length of each steel deformation inducing member 26A is approximately a few percent of the total length of the support 20. In this embodiment, the steel deformation inducing member 26A is composed of an H-shaped steel that is the same as the H-shaped steel that constitutes the steel support member 22, and more specifically, it is composed of an H-shaped steel whose cross-sectional shape is the same as the H-shaped steel that constitutes the steel support member 22 and has the same size. The H-shaped steel that constitutes the steel deformation induction member 26A is arranged with the web 2404 facing approximately the center of the cross section of the tunnel 10 and a pair of flanges 2402 facing the excavation direction X of the tunnel 10, as shown in Figure 3 (B).

[0012] Therefore, as shown in FIG. 4, the H-shaped steel constituting the steel deformation inducer member 26A is disposed so as to be turned by 90 degrees with respect to the H-shaped steel constituting the steel support member 22. As shown in FIG. Moreover, the H-shaped steel constituting the steel deformation induction member 26A is arranged so that its centroid coincides with the centroid of the H-shaped steel constituting the steel support member 22, taking into consideration the weight balance. In other words, since the steel deformation inducing member 26A has the same cross-sectional area as the steel support member 22, it functions in the same way as the steel support member 22 against axial force, and is a member that is more easily deformed than the steel support member 22 against bending moment. Therefore, by changing the direction of the H-shaped steel and arranging it, the steel deformation inducing member 26A becomes a steel member that deforms prior to the steel support member 22 when the load of the ground from the excavation surface 12 acts on the support structure 20. Specifically, when the load from the ground acts on the support 20 from the excavation surface 12, the cross-sectional modulus of the steel deformation inducing member 26A against the bending moment generated in the support 20 is made smaller than the cross-sectional modulus of the steel support member 22. In this case, the length and section modulus of the steel deformation inducing member 26A are appropriately set taking into consideration the amount of deformation when the load from the ground acts on the support 20 from the excavation surface 12, and the section modulus of the H-shaped steel is appropriately determined by the thickness T1 and width W1 of the web 2404 and the thickness T2 and width W2 of the pair of flanges 2402, as shown in Figure 3 (A).

[0013] Furthermore, as shown in FIG. 3(A), the flanges 2402 of the H-shaped steel constituting the steel support member 22 can be positioned at a certain distance from the surface of the primary sprayed concrete 14A. However, in the H-shaped steel constituting the steel deformation inducing member 26A, a pair of flanges 2402 are positioned opposite each other in the excavation direction X of the tunnel 10 as shown in FIG. 3(B). Therefore, it is considered that the ends of the pair of flanges 2402 will be close to the surface of the primary sprayed concrete 14A, and the secondary sprayed concrete 14B (see FIG. 1) will not be sprayed between the H-shaped steel constituting the steel deformation inducing member 26A and the surface of the primary sprayed concrete 14A. In such a case, as shown in FIG. 9, a long, thin bag body 28 made of cloth or the like filled with mortar 2802 may be prepared, and the bag body 28 may be placed between a pair of flanges 2402 and a web 2404 of the H-shaped steel constituting the steel deformation inducing member 26A and the surface of the primary sprayed concrete 14A.

[0014] As shown in Figures 5(A) and (B), the steel support member 22 and the steel deformation inducing member 26A are connected to a plate 29 constituting a steel connecting member via a bolt B1 and a nut N1. That is, as shown in FIG. 5(A), plates 29 are fixed to both longitudinal ends of the steel deformation inducing member 26A by welding, and plates 29 are fixed to the longitudinal ends of the adjacent steel support members 22 by welding. As shown in Figure 5 (B), plate 29 is formed in a square or circular shape with the H-shaped steel that constitutes the steel support member 22 and the steel deformation induction member 26A inside it, and two bolt insertion holes H1 are formed in plate 29. Then, the plates 29 at both ends of the steel deformation inducing member 26A are butted against the plates 29 at the ends of the steel support member 22, and a nut N1 is screwed onto the bolt B1 inserted into the bolt insertion hole H1. The plates 29 at both ends of the steel deformation inducing member 26A are fastened to the plates 29 at the ends of the steel support member 22, thereby connecting the steel support member 22 and the steel deformation inducing member 26A.

[0015] According to this embodiment, when a load from the ground surrounding the tunnel 10 acts on the excavation surface 12 and a bending moment in a direction reducing the tunnel cross-section acts on the support structure 20, the steel deformation inducing member 26A deforms prior to the steel support member 22, thereby absorbing the deformation of the ground and stabilizing the ground around the tunnel 10. In this case, since the steel deformation inducing member 26A is a steel member and the amount of deformation can be adjusted, it does not protrude significantly into the inside of the tunnel 10 as in the conventional case. 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. In addition, since H-shaped steel beams are used as the steel support member 22 and the steel deformation inducing member 26A, the steel support member 22 and the steel deformation inducing member 26A can be easily manufactured from commercially available products, which is advantageous in shortening the construction period of tunnel construction and reducing costs compared to the conventional technology described above. In particular, in this embodiment, the H-shaped steel that constitutes the steel support member 22 can be used as the steel deformation inducing member 26A, so that the steel deformation inducing member 26A can be manufactured at the same time as the steel support member 22, which is advantageous in shortening the construction period of tunnel construction and reducing costs compared to the conventional technology described above.

[0016] Next, with reference to Figures 6 to 8, we will explain a modified example of the first embodiment in which the steel support member 22 and the steel deformation inducing member 26A are connected via a bracket 30, bolts B1 and B2, and a nut N1 that constitute a connecting member instead of the plate 29. As shown in FIG. 7(A), two brackets 30 are provided and are made of metal. In detail, as shown in Figures 6(A) and (B), two bolt insertion holes H1 are formed at the longitudinal end of the H-shaped steel that constitutes the steel support member 22, in the center of the width of the web 2404, spaced apart in the longitudinal direction of the steel support member 22. Furthermore, two female threads F1 are formed at the center in the width direction of a pair of flanges 2402 of the H-shaped steel constituting the steel deformation induction member 26A, spaced apart in the longitudinal direction of the steel deformation induction member 26A. The two brackets 30 have the same shape and, as shown in Figures 8(A) and (B), comprise an elongated central plate portion 3002 and a pair of end plate portions 3004 connected to both longitudinal ends of the central plate portion 3002 via bent portions. The central plate portion 3002 and the pair of end plate portions 3004 each have two bolt insertion holes H2 formed therein at an interval in the longitudinal direction. As shown in Figures 7(A) and (B), the central plate portions 3002 of the two brackets 30 are attached to a pair of flanges 2402 of the H-shaped steel that constitutes the steel deformation induction member 26A by bolts B1 that are inserted through the bolt insertion holes H2 and screwed into the female threads F1. In addition, a pair of end plate portions 3004 of the two brackets 30 are abutted against webs 2404 of H-shaped steel that constitute adjacent steel support members 22 across the steel deformation inducing member 26A, and are attached by being fastened together to the H-shaped steel web 2404 by bolts B2 inserted into the bolt insertion holes H1, H2 and nuts N1 screwed onto the bolts B2. This modification also provides the same effects as the first embodiment. Incidentally, various conventionally known structures can be adopted for the configuration of the connecting member connecting the steel support member 22 and the steel deformation inducing member 26A, but the use of the plate 29 as in the first embodiment or the bracket 30 as in the modified example is advantageous in that it allows the steel support member 22 and the steel deformation inducing member 26A to be easily and reliably connected with a simple configuration. In the first embodiment and its modified examples, the case has been described in which the steel support member 22 and the steel deformation inducing member 26A are made of the same shaped steel, that is, H-shaped steel, and the direction of the cross-sectional shape of the H-shaped steel is changed by 90 degrees with respect to the tunnel excavation direction X. In the present invention, the shaped steel having the same cross-sectional shape used for the steel support member 22 and the steel deformation inducing member 26A is not limited to H-shaped steel, but may be other shaped steel such as channel steel or I-shaped steel, in which case it is sufficient to use the shaped steel as the steel support member 22 with the direction that increases the section modulus and use the shaped steel as the steel deformation inducing member 26A with the direction that decreases the section modulus, and the angle at which the direction of the cross-sectional shape of the shaped steel is changed with respect to the tunnel excavation direction X is not limited to 90 degrees and may be, for example, 30 degrees, 45 degrees, 60 degrees, etc. Furthermore, if the steel deformation inducing member 26A is made of a shaped steel or a steel material formed of a material that is, for example, lower in strength or rigidity than the material of the shaped steel constituting the steel supporting member 22, i.e., a material that is easily deformed, even if the sectional shape is the same as that of the shaped steel constituting the steel supporting member 22, the sectional shape can be used in the same direction as that of the shaped steel of the steel supporting member 22. Even in this case, the sectional shape of the steel deformation inducing member 26A may be changed in direction with respect to the tunnel excavation direction X. Of course, in the present invention, the members used for the steel supporting member 22 and the steel deformation inducing member 26A are not limited to shaped steel, and any steel member including a shaped steel whose sectional shape of the steel supporting member 22 and that of the steel deformation inducing member 26A are different from each other may be used. Even in this case, if a material that is more easily deformed than the material constituting the steel supporting member 22 is used, it is advantageous in easily manufacturing the steel deformation inducing member 26A. Furthermore, by using the steel deformation inducing member 26A having a section modulus smaller than that of the steel supporting member 22, the steel deformation inducing member 26A can be easily manufactured. In addition, in this embodiment, the cross-sectional shape of the steel deformation inducing member 26A is uniform along the longitudinal direction, but the cross-sectional shape of the steel deformation inducing member 26A may be gradually larger or gradually smaller along the longitudinal direction, or the middle part in the longitudinal direction may be smaller than both ends, making it easier to deform than the steel support member 22.

[0017] (Second embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. In the following embodiment, the same parts and members as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted or simplified, and the description will focus on the parts that are different from the first embodiment. In the second embodiment, as shown in FIG. 10, the steel deformation induction member 26B differs from the first embodiment in that it is composed of a channel steel having a web 2414 and a pair of flanges 2412 standing up from both ends of the web 2414. As in the first embodiment, the steel support member 22 is composed of an H-shaped steel having a pair of flanges 2402 facing approximately the center of the tunnel cross section and a web 2404 facing the excavation direction X of the tunnel 10. That is, in the second embodiment, the steel supporting member 22 and the steel deformation inducing member 26B are made of shaped steel having mutually different shapes. As shown in FIG. 10, the channel steel is arranged such that the centroid of the channel steel coincides with the centroid of the H-shaped steel when viewed in a plan view. The channel steel is positioned with the web 2414 facing the center of the tunnel cross section. As in the first embodiment, the length and section modulus of the steel deformation inducing member 26B are appropriately set taking into consideration the amount of deformation when the load from the ground acts on the support 20 from the excavation surface 12, and when the load from the ground acts on the support 20 from the excavation surface 12, the section modulus of the steel deformation inducing member 26B against the bending moment generated in the support 20 is formed to be smaller than the section modulus of the steel support member 22, making the steel deformation inducing member 26B a member that is more easily deformed than the steel support member 22.

[0018] As shown in Figs. 11 and 12, the steel support member 22 and the steel deformation inducer member 26B are connected via a bracket 32 ​​and bolts B3 and B4. Specifically, as shown in FIG. 11(B), two female threads F2 are formed on both widthwise sides of a pair of flanges 2402 at the longitudinal ends of the H-shaped steel constituting the steel support member 22. As shown in Figs. 11A) and 11B, a female thread F3 is formed on each of the two flanges 2412 of the channel steel constituting the steel deformation induction member 26B.

[0019] Two brackets 32 are provided. The two brackets 32 have the same shape and, as shown in FIGS. 12(A), (B) and (C), comprise a central plate portion 3202 and a pair of end plate portions 3204 bent from both ends of the central plate portion 3202. The pair of end plate portions 3204 are formed with dimensions that allow a pair of flanges 2402 of the H-shaped steel to be inserted between them. Two bolt insertion holes H3 are formed in the central plate portion 3202, and two bolt insertion holes H4 are each formed in the pair of end plate portions 3204. As shown in Figures 11(A) and (B), the central plate portions 3202 of the two brackets 32 are abutted against the ends of the channel steel that constitutes the steel deformation inducing member 26B and also against the ends of the steel support member 22, and the pair of end plate portions 3204 are fitted to a pair of flanges 2402 of the H-shaped steel, and the two brackets 32 are attached to the ends of the H-shaped steel with bolts B3 that are inserted into the bolt insertion holes H4 of the pair of end plate portions 3204 and screwed into the female threads F2 of the pair of flanges 2402. Additionally, the bracket 32 ​​is attached to the channel steel by means of a bolt B4 which is inserted through the bolt insertion hole H3 of the central plate portion 3202 and screwed into the female thread F3 of the flange 2412 of the channel steel.

[0020] In this second embodiment, as in the first embodiment, the steel deformation inducing member 26B is more easily deformed than the steel support member 22, and when a load from the ground surrounding the tunnel 10 acts on the excavation surface 12 and a bending moment in a direction that reduces the tunnel cross-section acts on the support structure 20, the steel deformation inducing member 26B deforms prior to the steel support member 22, thereby absorbing the deformation of the ground and stabilizing the ground around the tunnel 10. In this case, since the steel deformation inducing member 26B is a steel member and the amount of deformation can be adjusted, it does not protrude significantly into the inside of the tunnel 10 as in the conventional case. Therefore, when the 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 conventional technology described above, the lining work can be carried out more smoothly than in the conventional technology described above, which is advantageous in shortening the construction period for tunnel construction and reducing costs. In addition, since H-shaped steel is used as the steel support member 22 and channel steel is used as the steel deformation inducing member 26B, the steel support member 22 and the steel deformation inducing member 26B can be easily manufactured from commercially available products, which is advantageous in shortening the construction period of tunnel construction and reducing costs compared to the conventional technology described above. In addition to H-shaped steel and channel steel, other structural steels include I-shaped steel, angle steel, round steel, etc., and in the present invention, these may be used in any combination as the structural steels that make up the steel support member 22 and the steel deformation inducing member 26B.

[0021] (Third embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 13, the third embodiment is different from the first embodiment in that a steel deformation inducer 26C is made of reinforcing bar. As in the first embodiment, the steel support member 22 is composed of an H-shaped steel having a pair of flanges 2402 facing approximately the center of the tunnel cross section and a web 2404 facing the excavation direction X of the tunnel 10. The reinforcing bars constituting the steel deformation induction member 26C are arranged so that the centroids of the reinforcing bars coincide with the centroids of the H-shaped steel. As in the first embodiment, the length and section modulus of the steel deformation inducing member 26C are appropriately set taking into consideration the amount of deformation when the load from the ground acts on the support 20 from the excavation surface 12, and when the load from the ground acts on the support 20 from the excavation surface 12, the section modulus of the steel deformation inducing member 26C against the bending moment generated in the support 20 is formed to be smaller than the section modulus of the steel support member 22, making the steel deformation inducing member 26C a member that is more easily deformed than the steel support member 22.

[0022] As shown in FIG. 14, the steel support member 22 and the steel deformation inducer member 26C are connected via a bracket 34 and a bolt B5. In detail, as shown in Figures 14(A) and (B), two female threads F4 are formed on both widthwise sides of a pair of flanges 2402 at the longitudinal ends of the H-shaped steel that constitutes the steel support member 22.

[0023] The brackets 34 are made of metal and two are provided. The two brackets 34 have the same shape, and include a bracket body 3402 and a tubular member 3404, as shown in FIGS. The bracket body 3402 includes a central plate portion 3412 and a pair of end plate portions 3414 bent from both ends of the central plate portion 3412 . The pair of end plate portions 3414 are formed with dimensions that allow a pair of flanges 2402 of the H-shaped steel that constitutes the steel support member 22 to be inserted between them. Each of the pair of end plate portions 3414 has two bolt insertion holes H5 formed therein. The inner diameter of the cylindrical member 3404 is formed to have a dimension that allows the end of the reinforcing bar that constitutes the steel deformation induction member 26C to be fitted therein, and the cylindrical member 3404 is attached to the center of the central plate portion 3412 by welding. As shown in Figures 14(A) and (B), tubular members 3404 are fitted to both ends of the reinforcing bar that constitutes the steel deformation inducing member 26C, a pair of end plate portions 3414 are fitted to a pair of flanges 2402, and the two brackets 34 are attached to the ends of the H-shaped steel with bolts B5 that are inserted into bolt insertion holes H5 of the pair of end plate portions 3414 and screwed into the female threads F4 of the pair of flanges 2402.

[0024] In this third embodiment, as in the first embodiment, when a load from the ground surrounding the tunnel 10 acts on the excavation surface 12 and a bending moment in a direction reducing the tunnel cross section acts on the support structure 20, the steel deformation inducing member 26C is more easily deformed than the steel support member 22, and the steel deformation inducing member 26C deforms prior to the steel support member 22, thereby absorbing the deformation of the ground and stabilizing the ground around the tunnel 10. In this case, since the steel deformation inducing member 26C is a steel member and the amount of deformation can be adjusted, it does not protrude significantly into the inside of the tunnel 10 as in the conventional case. Therefore, when the load from the surrounding ground acts on the excavation surface 12, the ground can be stabilized by allowing the steel support 16 to deform to a certain extent and releasing the load, and since it does not protrude significantly into the inside of the tunnel 10 as in the conventional technology described above, lining work can be carried out more smoothly than in the conventional technology described above, which is advantageous in shortening the construction period for tunnel construction and reducing costs. In addition, since H-shaped steel beams are used as the steel support members 22 and reinforcing bars are used as the steel deformation inducing members 26C, the steel support members 22 and the steel deformation inducing members 26C can be easily manufactured from commercially available products, which is advantageous in shortening the construction period of tunnel construction and reducing costs compared to the conventional techniques described above. [Explanation of symbols]

[0025] 10. Tunnel 12 Excavation Surface 14. Shotcrete 14A Primary sprayed concrete 14B Secondary sprayed concrete 16 Steel shoring 18 Rock Bolt 20 Shoring 22 Steel support members 2402,2412 Flanges 2404, 2414 Web 26A, 26B, 26C Steel deformation-inducing members 28 Bag body 2802 Mortar 29 Plate 30, 32, 34 bracket 3002,3202,3412 Center plate part 3004,3204,3414 End plate 3402 Bracket body 3404 Cylindrical member B1, B2, B3, B4, B5 Bolts F1, F2, F3, F4 female thread H1, H2, H3, H4, H5 bolt holes N1 Nut

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, Steel deformation inducing members that are more easily deformed than the steel support members are arranged at multiple locations spaced apart in the extension direction of the support, The steel support member and the steel deformation induction member are made of the same shaped steel, The steel support member and the steel deformation inducer member are arranged by changing the direction of the cross-sectional shape of the shaped steel with respect to the excavation direction of the tunnel. A steel support structure characterized by:

2. The steel support member and the steel deformation inducer member are both composed of the same H-shaped steel having a pair of flanges and a web connecting the flanges, The H-shaped steel constituting the steel support member is arranged with the web facing the excavation direction of the tunnel, The H-shaped steel constituting the steel deformation induction member is arranged with the web facing the center of the tunnel cross section, 2. The steel support according to claim 1.

3. 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, Steel deformation inducing members that are more easily deformed than the steel support members are arranged at multiple locations spaced apart in the extension direction of the support, The steel support member and the steel deformation inducer member are made of shaped steel having different shapes. A steel support structure characterized by:

4. The steel support member is composed of an H-shaped steel having a pair of flanges and a web connecting the flanges, The H-shaped steel is arranged with the web facing the excavation direction of the tunnel, The steel deformation induction member is composed of a channel steel having a web and a pair of flanges standing from both ends of the web, The channel steel is arranged with the web facing the center of the tunnel cross section.

4. The steel support according to claim 3.

5. 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, Steel deformation inducing members that are more easily deformed than the steel support members are arranged at multiple locations spaced apart in the extension direction of the support, The steel support member is made of shaped steel, The steel deformation induction member is made of reinforcing bars. A steel support structure characterized by:

6. The length, cross-sectional shape, or section modulus of the steel deformation inducing member along the extension direction of the support, or the material constituting the steel deformation inducing member, are set in consideration of the deformation amount of the steel deformation inducing member when a load from the ground acts on the support from the excavation surface. The steel support according to any one of claims 1 to 5.

7. The section modulus of the steel deformation inducer member is smaller than the section modulus of the steel support member; The steel support according to any one of claims 1 to 6.

8. The steel deformation inducing member is formed of a material that is more easily deformed than the steel support member. The steel support according to any one of claims 1 to 6.

9. The steel support member and the steel deformation inducer member are connected via a connecting member. A steel support according to any one of claims 1 to 8.

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