JP2022130185A - Leg reinforcement structure for steel support - Google Patents

Abstract

To provide a leg reinforcement structure for a steel support which can be easily processed on site and whose dimensions and sizes can be changed according to the properties of natural ground, and can effectively prevent the steel support from sinking with a simple constitution.SOLUTION: The lower end of a steel support 11 is provided with: a bottom inner locking portion 12 provided to protrude in the axial direction X of a tunnel 30; a bottom connecting member 13 with an inner end 13a locked to the bottom inner locking portion 12, and arranged along a bottom 16a of a widening reinforcement overdrill portion 16 overdrilled on the outside of a leg 11a of the steel support 11; an oblique side connecting member 14 having a lower end 14a engaged with an outer end 13b of the bottom connecting member 13, and whose upper end 14b is locked by an upper projecting locking portion 18 projecting from a leg 11b of the steel support 11; a wire mesh member 15 supported by the oblique side connecting member 14 and attached to cover the outside thereof; and a spray hardening material 17 that is hardened by being sprayed so as to fill the widening reinforcement overdrill portion 16.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a leg reinforcement structure for steel shoring, and in particular, a leg of a steel shoring installed along an excavated inner wall surface of a tunnel having a cross-sectional shape including an arch-shaped portion at the top in a mountain tunnel construction method. The present invention relates to a leg reinforcement structure of a steel shoring that reinforces a part.

In the mountain tunnel construction method, for example, prior to constructing the secondary lining using a tunnel lining formwork (centre), the primary lining using shotcrete or shot mortar is applied along the excavated inner wall surface of the tunnel. The primary lining is made up of multiple steel rods installed at intervals in the axial direction of the tunnel and extending in the circumferential direction to absorb the load from the inner wall surface of the excavated tunnel immediately after excavation. It is formed by spraying shotcrete or shot mortar in a predetermined thickness on the spaced portions of these steel shorings while they are supported by steel shorings.

In addition, the steel shoring is installed from the arch-shaped portion of the upper part of the tunnel to the side wall, and for example, until the shoring of the lower part of the side wall and the shoring of the invert part are connected below this, excavation The load from the excavated inner wall surface of the tunnel immediately after is supported by grounding the lower end plates of the legs on both sides of the steel shoring to the bottom of the excavation on both sides of the excavated cross section including the arch-shaped part. It is designed to let

On the other hand, when the load from the excavated inner wall surface of the tunnel is supported by grounding the lower end plate of the leg of the steel shoring to the bottom of the side excavation, depending on the ground at the bottom of the excavation, the soil bearing capacity may be insufficient. Since there is a risk that the steel shoring will sink, the contact area of the lower end of the steel shoring with respect to the bottom of the side excavation is increased to distribute the load over a wider area. Techniques have also been developed to reinforce to prevent subsidence (see Patent Documents 1 and 2, for example).

Here, in the reinforcing structure of Patent Document 1, the leg of the tunnel is provided with a reinforcing structure projecting inwardly of the tunnel and continuous in the longitudinal direction of the tunnel and constructed so as to be in contact with the bottom surface of the tunnel. This reinforcing structure is embedded in the surface layer of the structure, one end of which is connected to the leg of the shoring, and the other end of which is arranged to protrude inward of the tunnel. A girder steel material that connects the steel materials together in the longitudinal direction of the tunnel is provided. The reinforcing structure of Patent Document 2 includes a base plate interposed between the leg of the steel shoring and the ground, and is integrated with the leg of the steel shoring and the base plate, along the ground. wing plates extending in the axial direction of the tunnel.

JP-A-2010-53570 Japanese Unexamined Patent Application Publication No. 2012-112104

However, in the reinforcing structures of Patent Document 1 and Patent Document 2, it is necessary to attach reinforcing steel materials, base plates, and wing plates to the legs of the steel shoring pit in advance by factory production, so the excavation ground of the tunnel is difficult. Depending on the nature of the natural ground, it may be difficult to respond quickly and flexibly, and there is also the issue of cost. For this reason, on-site processing and fabrication are facilitated, and the dimensions and sizes can be easily changed according to changes in the nature of the ground, and the steel shoring can be prevented from sinking with a simple configuration. It is desired to develop a new reinforcing structure that can effectively prevent this.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to easily carry out on-site processing and fabrication, to easily change the dimensions and sizes according to changes in the nature of the natural ground, and to construct a steel shoring with a simple structure. To provide a leg reinforcement structure for a steel shoring which can effectively prevent subsidence of a steel shoring.

In the mountain tunnel construction method, the present invention is a steel shoring that reinforces the leg that is the lower end portion of the steel shoring installed along the excavated inner wall surface of the tunnel having a cross-sectional shape including an arch-shaped portion at the top. A pair of leg reinforcement structures that project from the steel shoring on both sides in the axial direction of the tunnel at the lower end of the steel shoring installed from the arch-shaped portion to the side wall of the tunnel and an inner end portion of the bottom side inner locking portion of the pair of bottom side inner locking portions, respectively, and a widening reinforcing overdrill overdrilled outside the lower end portion of the steel shoring. a pair of bottom side joint members arranged along the bottom of the steel shoring; lower ends of which are engaged with outer ends of the pair of bottom side joint members; A pair of oblique side joint members respectively engaged with the upper overhanging engaging portions provided overhanging on both sides in the axial direction of the tunnel; and a wire mesh-like member attached to cover the outer side of the wire mesh-like member, and are sprayed so as to fill the widening reinforcing overgrow part and hardened integrally with the bottom side joint member, the oblique side part joint member, and the wire mesh-like member The above objects have been achieved by providing a steel shoring leg reinforcement structure for mountain tunnel construction, which is composed of a spray hardening material as described above.

Further, in the steel shoring leg reinforcement structure of the present invention, a steel plate for expanding the contact area is disposed under the lower end plate of the steel shoring to expand the contact area. It is preferable that the pair of bottom side inner locking portions are fixed to the both side overhanging portions of the ground contact surface enlarging steel plate. .

Further, in the leg reinforcement structure of the steel shoring of the present invention, the steel plate for enlarging the contact surface uses a bolt member via a cap nut fixed to the upper surface side of the lower end plate of the steel shoring. preferably mounted overlapping the lower end plate.

Further, in the steel shoring leg reinforcement structure of the present invention, the oblique side joint member is provided with a hook-shaped engaging portion at one end serving as the upper end and the other end serving as the lower end. It is preferably an elongated strip-shaped steel plate member with a cylindrical locking portion attached to the portion.

Furthermore, in the leg reinforcement structure of the steel shoring of the present invention, it is preferable that the bottom joint member is a reinforcing bar having both ends bent as locking portions.

Further, in the steel shoring leg reinforcement structure of the present invention, the upper projecting locking portion is attached across the space between a pair of steel shorings adjacent to each other in the axial direction of the tunnel. It is preferable to use a splicing member.

Further, in the steel shoring leg reinforcement structure of the present invention, each of the pair of steel shorings adjacent to each other with a space is provided with the pair of bottom side inner locking portions and the pair of bottom side joint members. , and the pair of oblique side joint members are attached, and the widening reinforcing overgroove is continuously formed on the outer side of the lower end portions of the pair of adjacent steel shorings so as to straddle these regions. The wire netting member is supported by each of the pair of oblique side joint members and attached so as to cover the outer side thereof continuously so as to straddle these regions, and the spray hardening is performed. The material is continuously sprayed so as to cover the outer region of the lower end portion of the adjacent pair of steel shoring so as to fill the whole of the over-excavated widening reinforcement over-digging part, It is preferable that the base part joint member, the oblique side part joint member and the wire mesh member are integrally cured.

According to the leg reinforcement structure of the steel shoring of the present invention, it can be easily processed and manufactured on site, and the dimensions and sizes can be easily changed according to changes in the nature of the natural ground. In addition, the simple structure can effectively prevent the steel shoring from sinking.

FIG. 1 is an enlarged cross-sectional view of part A in FIG. 4(a) for explaining the configuration of a leg reinforcement structure for a steel shoring according to a preferred embodiment of the present invention. FIG. 2 is a plan view along BB in FIG. 1, explaining the configuration of the leg reinforcement structure of the steel shoring according to a preferred embodiment of the present invention. FIG. 3 is a state before a wire mesh-like member is installed in a portion between a pair of adjacent steel shorings, explaining the configuration of the steel shoring leg reinforcement structure according to a preferred embodiment of the present invention. is an enlarged perspective view of the leg of the. Fig. 4(a) is a schematic cross-sectional view explaining the steel shoring installed along the excavated inner peripheral surface of the upper part of the side wall from the arch-shaped portion of the tunnel, and Fig. 4(b) is the ground further below. is a schematic cross-sectional view of a state in which the shoring at the lower part of the side wall is connected to the steel shoring. Fig. 5(a) is a schematic cross-sectional view explaining the steel shoring installed along the excavated inner peripheral surface of the lower part of the side wall from the arch-shaped portion of the tunnel and the shoring of the lower part of the side wall, Fig. 5(b) [Fig. 2] is a schematic cross-sectional view showing a state in which the ground further below is excavated and the shoring for the invert section is connected to the shoring at the lower portion of the side wall.

A steel shoring leg reinforcement structure 10 according to a preferred embodiment of the present invention is excavated by a known mountain tunnel construction method such as the NATM construction method, for example, as a tunnel having a cross-sectional shape including an arch-shaped portion at the top, In a tunnel 30 preferably having a horseshoe-shaped cross section (see FIGS. 4B and 5B), as shown in FIG. , the lower end portion 11a of the steel shoring 11 installed along the excavated inner wall surface 32 at the upper part of the side wall from the excavated arch-shaped portion excavates the ground below the steel shoring 11, FIG. Reinforcement to effectively prevent sinking due to the load from the excavated inner wall surface 32 immediately after excavation until the shoring 33 at the lower part of the side wall shown in b) is connected. It was adopted as a structure. The steel shoring leg reinforcement structure 10 of the present embodiment has a simple structure, and by increasing the contact area of the steel shoring 11 with the excavation side bottom surface 31 of the tunnel 30, Settlement of the lower end portion 11a of the steel shoring 11 at the portion 31 can be effectively suppressed and avoided, and the constituent members can be easily processed and manufactured on site. The dimensions and size can be easily changed according to changes in the properties of the material.

The steel shoring leg reinforcement structure 10 of the present embodiment is installed along the excavated inner wall surface 32 of the tunnel 30 having a cross-sectional shape including an arch-shaped portion at the top in the mountain tunnel construction method. It is a reinforcing structure for reinforcing the leg that is the lower end portion 11a of the shoring 11 (see FIGS. 4(a) and 4(b)), and is a steel shoring installed from the arch-shaped portion of the tunnel 30 to the side wall portion. 1 to 3, at the lower end of the tunnel 11, a pair of bottom inner locking portions 12 projecting from the steel shoring 11 to both sides in the axial direction X of the tunnel 30; The inner end portions 13a are respectively locked to the pair of bottom inner locking portions 12, and along the bottom portion 16a of the widening reinforcement overcut portion 16 overcut on the outside of the leg portion 11a of the steel shoring 11. A pair of bottom side joint members 13 arranged in a row, and lower end portions 14a are respectively engaged with outer ends 13b of the pair of bottom side joint members 13, and upper end portions 14b are the legs of the steel shoring 11. A pair of oblique side joint members 14 respectively engaged with upper projecting engagement portions 18 provided to project from the portion 11b on both sides in the axial direction X of the tunnel 30, and straddling the pair of oblique side joint members 14. The wire mesh member 15 supported and attached covering the outer side of these, and the bottom side joint member 13, the oblique side portion joint member 14, and the metal wire are sprayed so as to fill the widening reinforcing overgroove 16. It is composed of a net-like member 15 and a spray hardening material 17 which is hardened integrally.

Further, in the present embodiment, the ground contact area enlarging steel plates 19 are placed under the lower end plate 11c of the steel shoring 11 to expand the ground contact area. The pair of bottom side inner locking portions 12 are fixed to both side overhanging portions 19a of the steel plate 19 for enlarging the contact surface.

Furthermore, in this embodiment, as shown in FIG. 3, each pair of steel shorings 11 adjacent to each other with a space is provided with a pair of bottom side inner locking portions 12, a pair of bottom side joint members 13, and a pair of oblique side joint members 14 are attached, respectively, and the widening reinforcement overgroove 16 is continuous to the outside of the lower end portion 11a of each pair of adjacent steel shorings 11 so as to straddle these regions. As shown in FIG. 2, the wire mesh member 15 is continuously supported by the pair of oblique side joint members 14 and covers the outside of these regions so as to straddle these regions. The blast hardening material 17 (see FIG. 1) is continuously applied over the outer area of the lower end portion 11a of each pair of adjacent steel shorings 11, and the overdrilled widening reinforcement It is sprayed so as to fill the entire overgrown portion 16 and hardens integrally with the bottom side joint member 13 , the oblique side portion joint member 14 and the wire mesh member 15 .

In this embodiment, the steel shoring 11 installed along the excavated inner wall surface 32 of the tunnel 30 is made of, for example, H-shaped steel, as shown in FIGS. It can be formed by bending into a shape that includes an arcuate portion along 32 . The steel shoring 11 is arranged along the excavated inner wall surface 32 of the tunnel 30 by a known construction method as the excavation work of the tunnel 30 progresses in the region adjacent to the face surface of the tunnel 30, In the axial direction X (see FIG. 2) of the tunnel 30, the outer flange 11d, which is the outer peripheral surface, faces the excavated inner wall surface 32 of the tunnel 30 (see FIG. 1) at an interval of, for example, about 100 cm. They will be installed sequentially.

As shown in FIGS. 1 and 3, the bottom inner engaging portion 12 constituting the leg reinforcing structure 10 of the present embodiment is made of, for example, a steel cylindrical sleeve member. By fixing to the projecting portions 19a on both sides of the steel plate 19 for enlarging the contact surface, which is attached to the lower end plate 11c of the steel shoring 11, the steel shoring is installed at the lower end of the steel shoring 11. 11 to both sides of the tunnel 30 in the axial direction X. The steel plate 19 for enlarging the contact surface has a vertically long rectangular planar shape with an increased length in the axial direction X of the tunnel 30, and is provided below the lower end plate 11c having a substantially square planar shape. 21a and bolt members 21b, the projecting portions 19a project from the lower end plate 11c on both sides of the tunnel 30 in the axial direction X. As shown in FIG. In the present embodiment, the bottom inner locking portion 12 made of a steel cylindrical sleeve member extends in the axial direction X of the tunnel 30 along the outer edge portions of the overhanging portions 19a on both sides of the steel plate 19 for enlarging the contact surface. , and are fixed to each other by welding or the like.

Further, in the present embodiment, the lower end plate 11c, which serves as the connection plate of the steel shoring 11, has the shoring 33 ( 1) and cap nuts 21a are provided on both sides of the H-shaped steel rib plate 11e (see FIG. 2). By tightening bolt members 21b (see FIG. 1) using these connection holes and cap nuts 21a, the steel plate 19 for enlarging the contact surface can be firmly attached to the lower end plate 11c integrally. It has become. A ground contact area enlarging steel plate 19 is integrally attached to the lower end plate 11c of the steel support 11, thereby enlarging the contact area of the lower end plate 11c of the steel support 11 and dispersing stress. Thus, the erected steel shoring 11 can be installed in a more stable state until the spray hardening material 17 that is sprayed to fill the widening reinforcing overgrow part 16 hardens. be possible.

In this embodiment, the bottom joint member 13, which is locked by the bottom inner locking portion 12 protruding from the steel shoring 11, is inserted and locked into the cylindrical bottom inner locking portion 12. As shown in FIG. 3, preferably both ends 13a and 13b are vertically bent as locking portions. The length of the base joint member 13 made of a reinforcing rod can be easily adjusted by cutting the straight portion between the ends 13a and 13b on both sides or joining them by welding or the like. ing. The bottom joint member 13 is formed along the bottom portion 16a of the widened reinforcement overdrill portion 16 which is overdrilled so as to preferably have a substantially right-angled triangular cross-sectional shape on the outside of the leg portion 11a of the steel shoring 11. , are arranged side by side in parallel on both sides of each steel shoring 11, and are provided so as to form a substantially right-angled triangular base. Each bottom side joint member 13 has one inner end portion 13a inserted and locked into the cylindrical bottom side inner locking portion 12, and the other outer end portion 13b having an oblique side portion joint member. Cylindrical locking portions 14a at the lower ends of 14 are locked.

In this embodiment, as shown in FIGS. 2 and 3, the hypotenuse joint member 14 is preferably an elongated strip-shaped steel plate member, which connects the lower end portion 11a of each steel shoring 11 . A pair of them are arranged side by side in parallel on both sides of the sandwich. The oblique side joint member 14 made of a steel plate member is provided with a hook-shaped engaging portion 14b at one end serving as the upper end portion, for example, in a U-shaped curved and folded state, and at the lower end. A cylindrical locking portion 14a is attached, for example, by welding a steel pipe member to the other end, which serves as a portion. Each of the oblique side joint members 14 has hook-shaped locking portions 14b at the upper ends thereof, and upper projecting locking portions 18 that project from the side walls of the steel shoring 11 on both sides in the axial direction X of the tunnel 30. As a result, it is preferably hooked to the shoring joint member 22 to be described later, and the outer end 13b of the bottom side joint member 13 is inserted and locked from the lateral direction into the cylindrical locking portion 14a at the lower end. By doing so, each is provided so as to form a substantially right-angled triangular hypotenuse. The hypotenuse joint member 14 made of an elongated strip-shaped steel plate member is formed by, for example, cutting a straight portion between the locking portions 14a and 14b on both sides or joining them by welding or the like to extend the length. can be easily adjusted.

Here, in this embodiment, as shown in FIG. A shoring joint member 22 is attached which functions as a spacer to allow the predetermined spacing to be maintained. The shoring joint member 22 is made of, for example, a rebar rod preferably having a predetermined length, which is obtained by vertically bending the end locking portions 22a on both sides. The shoring joint member 22 is formed at a joint angle with the rib plate 11e at the inner side of the outer flange 11d facing the excavated inner wall surface 32 of the tunnel 30 at the leg portion 11a, which is the lower end portion of each of the adjacent steel shorings 11. By inserting and locking the end locking portions 22a on both sides into the locking sleeves 11f fixed by welding or the like to the shoring section 11, both sides of the tunnel 30 in the axial direction X from the leg portions 11a of the steel shoring 11 are locked. It is installed in an overhanging state. In this embodiment, these shoring joint members 22 are used as the upper projecting locking portion 18 so that the hook-shaped locking portion 14b at the upper end of the oblique side joint member 14 can be locked. It's becoming

In this embodiment, the wire mesh member 15 attached to cover the outer side of the plurality of oblique side joint members 14 is embedded in a hardening material such as shot concrete or shot mortar. As a member that reinforces these, various known wire mesh members can be appropriately selected and used. The wire mesh member 15 is disposed along the excavated inner wall surface 32 of the tunnel 30 from the arch-shaped portion to the upper part of the side wall, where a spray hardening material such as spray concrete is sprayed as a primary lining. 1, in the widening reinforcing overgroove 16 on the outer side of the leg 11a of the steel shoring 11, along the oblique side of the substantially right-angled triangular cross-sectional shape, a plurality of oblique side joint members 14 are straddled. are supported and attached over these exteriors by known attachment methods. Further, in the present embodiment, as described above, the width-enlarging reinforcing overgrown portions 16 are continuously overgrown outside the lower end portions 11a of each pair of adjacent steel shorings 11 so as to straddle these regions. Therefore, as shown in FIG. 2, the wire mesh-like member 15 is continuously attached so as to straddle these regions, supported by each pair of oblique side joint members 14, and attached so as to cover the outside thereof. become.

After installing these members constituting the leg reinforcement structure 10 of the present embodiment, along the excavated inner wall surface 32 of the tunnel 30 extending from the arch-shaped portion to the lower part of the side wall, preferably as the shot hardening material 17, shot concrete is applied. By spraying to construct the primary lining and continuously spraying shotcrete onto the width-enlarging reinforcement overgrowth 16 so as to fill the width-enhancement reinforcement overgrowth 16, the leg reinforcement structure is provided. form 10; Further, in the present embodiment, as described above, the width-enlarging reinforcing overgrown portions 16 are continuously overgrown outside the lower end portions 11a of each pair of adjacent steel shorings 11 so as to straddle these regions. Therefore, the spray hardening material 17 (see FIG. 1) is continuously applied over the outer region of the lower end portion 11a of each pair of adjacent steel shorings 11, and the overgrooved widening reinforcement margin It is sprayed so as to fill the entire trench 16 . The sprayed hardening material 17 made of, for example, sprayed concrete hardens integrally with the bottom side joint member 13, the oblique side joint member 14, and the wire mesh member 15, thereby forming the steel shoring of the present embodiment. A leg reinforcement structure 10 is formed.

According to the steel shoring leg reinforcement structure 10 of the present embodiment having the above-described configuration, it is possible to easily process and manufacture the constituent members at the site, and at the same time, it is possible to control the nature of the natural ground. It is possible to easily change the dimension and size according to changes, and to effectively prevent the steel shoring from sinking with a simple structure.

That is, according to the present embodiment, the leg reinforcement structure 10 includes a pair of bottom side inner locking portions 12 provided overhanging from the steel shoring 11 on both sides in the axial direction X of the tunnel 30, and these bottom sides A pair of bottom side joint members 13 that are locked to the inner side locking portion 12 and arranged along the bottom portion 16a of the widened reinforcing overgroove portion 16; and a pair of oblique side joint members 14 whose upper ends 14b are engaged with the upper overhanging engaging portion 18; A wire mesh member 15, and a spray hardening material 17 that is sprayed so as to fill the widening reinforcing overgrow portion 16 and hardened integrally with the bottom side joint member 13, the oblique side portion joint member 14, and the wire mesh member 15. is composed of

Thus, according to the present embodiment, for example, by appropriately adjusting the thickness and width of the base portion joint member 13 and the oblique side portion joint member 14, and by appropriately adjusting the length thereof, it is possible to adapt to changes in the nature of the natural ground. Accordingly, it becomes possible to easily change the dimensions and size, and it becomes possible to easily carry out processing and manufacturing on site. In addition, the work of filling the width-enlarging reinforcing overgrowth portion 16 with the hardening spray material 17 can be easily performed by following the work of constructing the primary lining using, for example, shotcrete as the hardening spray material 17. At the same time, the spray hardening material 17 sprayed on the widening reinforcing overgrow part 16 is integrated with the bottom part joint member 13, the oblique side part joint member 14, the wire mesh member 15 and the leg part 11a of the steel shoring 11. By hardening, the contact area of the lower end of the steel shoring 11 with respect to the excavation side bottom surface 31 is increased, and the load is distributed over a wider area, so that the steel shoring can be achieved with a simple configuration. It is possible to effectively prevent the work 11 from sinking.

It should be noted that the present invention is not limited to the above embodiments, and various modifications are possible. For example, the hypotenuse joint member does not necessarily have to be an elongated strip-shaped steel plate member, and may be a round steel bar, a deformed reinforcing bar, an FRP rod-shaped member, a plate-shaped member, or the like. The locking portions at one end and the other end of the oblique side joint member may have various structures other than the hook-shaped locking portion and the cylindrical locking portion. The bottom joint member does not necessarily have to be a reinforcing bar with both ends bent as locking portions, and may be a round steel, a long steel plate, an FRP rod-shaped member, or the like. By adopting a non-circular cross-sectional shape such as a star shape or a polygonal cross-sectional shape other than a circular cross-sectional shape, it is possible to improve compatibility with, for example, shotcrete. The locking portions at one end and the other end of the bottom side joint member may also have various structures other than hook-shaped locking portions.

In addition, the width-enlarging reinforcement overdug portion does not necessarily need to be continuously overdug so as to straddle these regions outside the lower end portions of a pair of adjacent steel shorings. It does not have to be attached continuously across the area of . The widening reinforcement overgrowth and the wire mesh member may be provided independently on the outside of the leg of each steel shoring, and the spray hardening material is applied to each widening reinforcement overgrowth. It may be filled and hardened integrally with the base joint member, the oblique side joint member and the wire mesh member.

Furthermore, as shown in FIGS. 4(a) and 4(b), the leg reinforcement structure 10 of the steel shoring of the present invention has an excavated arch at the stage when the tunnel 30 is excavated from the arch-shaped portion to the upper part of the side wall. The lower end portion 11a of the steel shoring 11 installed along the excavated inner wall surface 32 at the upper part of the side wall from the shape portion is effectively prevented from sinking due to the load from the excavated inner wall surface 32 immediately after excavation. In addition to being adopted as a reinforcing structure for preventing the erosion, preferably, as shown in FIG. The steel shoring 11 and the shoring 33 at the bottom of the side wall, which are installed along the excavated inner wall surface 32 at the bottom of the side wall, excavate the ground below the shoring 33 at the bottom of the side wall to form the structure shown in FIG. It is adopted as a reinforcing structure for effectively preventing sinking due to the load from the excavation inner wall surface 32 until the shoring 34 for the invert portion shown is connected. is also possible.

10 Steel shoring leg reinforcement structure 11 Steel shoring 11a Leg (lower end portion)
11c lower end plate 11d outer flange 11e rib plate 11f lock sleeve 12 bottom inner locking portion 13 bottom joint member 13a inner end 13b outer end 14 oblique joint member 14a lower end (cylindrical locking portion)
14b Upper end (hook-shaped locking part)
15 Wire net-like member 16 Widening reinforcing overgrown portion 16a Bottom portion 17 Spray hardening material 18 Upper overhang locking portion 19 Ground contact surface enlarging steel plate 19a Overhanging portion 21a Cap nut 21b Bolt member 22 Shoring joint member 22a End locking portion 30 Tunnel 31 Excavation side bottom surface 32 Excavation inner wall surface 33 Side wall lower shoring 34 Inverted shoring X Tunnel axial direction

Claims (7)

In the mountain tunnel construction method, leg reinforcement of steel shoring to reinforce the leg, which is the lower end of the steel shoring, installed along the excavated inner wall surface of the tunnel having a cross-sectional shape including an arch-shaped part at the top is a structure,
a pair of bottom inner locking portions protruding from the steel shoring on both sides in the axial direction of the tunnel at the lower end of the steel shoring installed from the arch-shaped portion to the side wall of the tunnel; The inner end portions are respectively locked by the pair of bottom side inner locking portions, and are arranged along the bottom portion of the widening reinforcing overdrill portion overcut outside the lower end portion of the steel shoring. A pair of bottom side joint members, and lower ends of which are respectively engaged with the outer ends of the pair of bottom side joint members, and upper ends of which project from the side walls of the steel shoring to both sides in the axial direction of the tunnel. a pair of oblique side joint members respectively engaged with the upper overhanging engaging portions, and a metal supported so as to straddle the pair of oblique side joint members and attached to cover the outside thereof and a spray hardening material that is sprayed so as to fill the widening reinforcing overgrow portion and hardened integrally with the bottom side joint member, the oblique side joint member and the wire net member. Leg reinforcement structure of steel shoring in mountain tunnel construction method. A steel plate for expanding the contact area, which is arranged under the lower end plate of the steel shoring and expands the contact area, is attached so as to protrude from the lower end plate to both sides in the axial direction of the tunnel, 2. The leg reinforcement structure of a steel shoring in a mountain tunnel construction method according to claim 1, wherein said pair of bottom side inner locking portions are provided by being fixed respectively to the projecting portions on both sides of said steel plate for enlarging the contact surface. 3. The steel plate according to claim 2, wherein the steel plate for enlarging the contact surface is attached to the lower end plate of the steel shoring via a cap nut fixed to the upper surface side of the lower end plate of the steel shoring using a bolt member. Leg reinforcement structure of steel shoring in mountain tunnel construction method. The oblique side joint member has a hook-shaped engaging portion provided at one end serving as the upper end, and a cylindrical engaging portion attached to the other end serving as the lower end. A leg reinforcement structure for a steel shoring in a mountain tunnel construction method according to any one of claims 1 to 3, wherein the steel plate member is a strip-shaped steel plate member. The leg reinforcement of the steel shoring in the mountain tunnel construction method according to any one of claims 1 to 4, wherein the bottom joint member is a reinforcing bar with both ends bent as locking portions. structure. 6. Any one of claims 1 to 5, wherein said upper overhang locking portion is formed by a shoring joint member attached across an interval between a pair of said steel shorings adjacent in the axial direction of the tunnel. 2. A leg reinforcement structure for steel shoring in the mountain tunnel construction method according to claim 1. Each of the pair of spaced-adjacent steel shorings is attached with the pair of bottom inner locking portions, the pair of bottom side joint members, and the pair of oblique side joint members, The width-enlarging reinforcement overdug part is continuously overdug so as to straddle these regions outside the lower end portions of the pair of adjacent steel shorings, and the wire mesh member straddles these regions. and is mounted over and supported by each of said pair of hypotenuse joint members in a continuous manner such that said blast hardening material is applied to the lower end portions of said adjacent pair of said steel shorings. The bottom side joint member, the oblique side joint member, and the wire mesh member are continuously sprayed so as to fill the entire width-enlarging reinforcing overdrill portion that has been over-drilled so as to straddle the outer region. The leg reinforcement structure of the steel shoring in the mountain tunnel construction method according to any one of claims 1 to 5, which is integrally hardened.

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