JP4296545B2 - Center-pillar structure of eyeglass tunnel - Google Patents

Description

  The present invention relates to a center pillar structure of a spectacle tunnel, and in particular, a center having a structure capable of reliably supporting a main shaft arch supporting work accompanying excavation of a main shaft and capable of reliably bearing a tunnel earth covering load in a completed structure system. It relates to the pillar structure.

  For example, as shown in FIG. 4, in a road tunnel or the like, a central bulkhead column 11 (hereinafter referred to as a center pillar 11) made of reinforced concrete constructed in a central advanced guide shaft 10 with the upper and lower lanes being very close to each other. .) Is a shared structure part, and it is called a proximity tunnel (a double tunnel, a glasses tunnel, etc.) that supports a part of the load of the two main tunnels 20 and 30 parallel to the center pillar. In this specification, it is called a glasses tunnel).

  FIG. 5 is a load diagram schematically showing a load state acting on the center pillar 11 in the steel tunnel illustrated in FIG. As shown in the figure, the center pillar 11 acts on the natural ground load in the upper natural rock loosening range 1 between the two main tunnels 20 and 30 and the upper half of the main tunnels 20 and 30 for spraying. The axial compression force acting through the concrete 21, 31 and the steel arch support work is reliably supported, so that the entire eyeglass tunnel can be stabilized. As shown in the figure, the wall pillar portion 11d of the center pillar 11 is a member in which the vertical load among the loads acting on the tunnel is excellent as an axial compression force, and a structural design capable of withstanding this axial compression force is required. .

  When attention is paid to the detailed structure of the center pillar 11 at the tunnel construction stage, the center pillar 11 is excavated at an intermediate position between the two main tunnels 20 and 30 (see FIG. 4) as shown in FIG. For example, the cross-sectional shape is constructed in the central advanced guide shaft 10 having a horseshoe-shaped tunnel, and the cross-sectional shape is a substantially inverted T-shape following the main shaft tunnel side wall shape 11a and main shaft invert shape 11b. It is constructed continuously along the extending direction. As shown in FIG. 7, when excavating the main tunnel, the upper half load of the tunnel is supported by the shotcrete 21 and the steel arch support work 14 (hereinafter referred to as arch support work). 14 a is structured to be supported by the shoulder of the center pillar 11. Therefore, in this construction stage, the upper half load of the main tunnel 20 is applied to the center pillar 11 from the shot concrete 21 and the leg 14a of the arch support work 14 constructed along the upper half arch ( Shoulder 11c → wall pillar 11d → bottom plate 11e).

  As described above, the center pillar 11 includes the construction stages of the advanced main tunnel 20 and the reverse main tunnel 30 (hereinafter referred to as the advanced main tunnel 20 and the reverse main tunnel 30) excavated back and forth, and the completed structural system. Must be safe in all stress states. For this reason, the center pillar top part is designed to efficiently connect the center pillar top part and the advanced guide shaft top part as a way to increase the rigidity of the structure system of the center pillar and efficiently construct the center pillar. Has also been proposed (Patent Document 1).

  When the center pillar is constructed by the construction method disclosed in Patent Document 1, the center pillar has a configuration in which the lower end has a fixed end as the bottom plate of the entire invert in the advanced guide shaft, and the upper end is fixed to the top of the advanced guide shaft. .

See JP 2002-322898 A.

  By the way, in the above-mentioned patent document 1, it has been confirmed that the center pillar having a structure in which the upper end and the lower end are firmly held is close to the behavior as a both-end fixed plate. It was confirmed that the safety of the stress state of the entire center pillar can be secured by restraining the displacement at almost the middle position in the height direction. However, various load states occur at the construction stage of this spectacle tunnel. For example, as shown in FIG. 7, in the construction stage to be built when excavating the advanced main mine, the leg portion 14a of the arch support 14 is supported by the shoulder portion 11c of the center pillar 11, and the arch support work is supported on the shoulder portion 11c. The axial compression force from 14 acts as a concentrated load (white arrow) having an angle substantially equal to the tangential direction of the arch support leg 14a.

FIG. 8 is an enlarged view showing the detailed structure. As shown in the figure, in the shoulder 11c of the center pillar 11, the following structural problems have been pointed out.
(1) There is a possibility that a shear crack C may occur at the base of the shoulder 11c due to an excessive axial compression force acting from the arch support leg 14a.
(2) Since the shoulder 11c is slightly inclined to transmit the axial compression force generated along the arch shape in the axial direction of the concrete member, there is a risk that the arch support will slide toward the sky inside the tunnel. is there.
(3) Although the base plate of the leg portion 14a of the arch support is installed on the shoulder 11c of the center pillar, there is a possibility that it will collapse due to insufficient bearing strength of the concrete surface coupled with the punching shear.

  Also in the completed structure system shown in Fig. 5, the ground in the tunnel construction section is weak, and the proximity distance between the main tunnels cannot be secured due to the tunnel plane alignment and construction limits, so the center pillar In some cases, the cross section (thickness) of the wall column portion 11d cannot be secured sufficiently. In this case, since the outer shape of the center pillar cannot be changed, it is necessary to design as a composite structure such as a steel reinforced concrete structure using high strength concrete, increasing the amount of reinforcing bars, or combining steel materials such as H-shaped steel. However, the central advanced guide shaft has a small internal cross section, so there are cases where it is not possible to actually construct a center pillar with an excessive reinforcement arrangement or a design using steel.

  Further, regarding the reinforcement of the shoulder portion 11c of the center pillar 11 that supports the leg portion 14a of the arch support work 14, the base plate of the leg portion 14a is fixed to the center pillar 11 with an anchor bolt (not shown), or the shoulder portion 11c. It is conceivable to deal with this by arranging a large amount of reinforcing bars, but there are cases where actual construction is difficult as in the above-described reason.

    Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, and to simplify the detailed structure of the center pillar that supports the arch support during excavation of the advanced main mine by a simple reinforcing structure. An object of the present invention is to provide a center pillar structure having a structure capable of reliably bearing the earth covering load of the main tunnel in the completed structure system so that excessive stress is not generated in the center pillar as a solid structure.

  In order to achieve the above object, the present invention is provided in advance as a shared support structure in an advanced guide shaft located between two main shafts of a spectacle tunnel constructed in close proximity to each other. A center pillar structure that supports the support leg and bears a ground load between the main shafts, and the shoulder supporting the upper half arch support leg of the main shaft has the arch support support leg. The bearing steel plate for placing and holding the part is characterized in that a part thereof is embedded and fixed in concrete via an anchor.

  The anchor is preferably a hook-like portion obtained by bending the rear end of the bearing steel plate or a plurality of studs planted on the lower surface of the bearing steel plate.

  It is preferable that the bearing steel plate is bent in accordance with the shape of the shoulder portion and a stud is implanted on the back side thereof.

  Moreover, in the completed structure system, when a large load is applied, it is provided in advance as a shared support structure in the advanced guide shaft located between the two main shafts of the eyeglass tunnel that is constructed in close proximity to each other, A center pillar structure that supports the arch support leg of the main mine and bears a ground load between the main mine, and a concrete steel pipe column filled in the center pillar is predetermined along the tunnel extending direction. Standing at intervals, the bearing steel plate for mounting and holding the arch support leg on the shoulder supporting the upper half arch support leg of the main mine, part of which is anchored And embedded in concrete and fixed.

  According to the present invention, in the construction of the eyeglass tunnel, the shoulder of the center pillar that supports the legs of the arch support work accompanying excavation of the main mine can be made simple and rigid, and in the completed structure system Has the effect of being able to reliably support the axial compression force generated by the earth cover load of the main tunnel.

  Hereinafter, the best mode for carrying out the center pillar structure of the eyeglass tunnel of the present invention will be described with reference to the accompanying drawings.

  Hereinafter, the structure of the center pillar structure of the present invention will be described with reference to FIGS. The center pillar structure shown in FIG. 1 is an embodiment that can support a vertical axial compressive force borne by the wall pillar portion of the center pillar as a reinforced concrete structure in the completed structure system.

As shown in FIG. 1, the cross-sectional shape of the center pillar of this embodiment is a substantially inverted T shape in which the side wall shape and invert shape of the main tunnel are smoothly continuous, and the top is left at the central advanced guide shaft. It has an arc shape that follows the shape of the top support. As concrete, concrete with a design standard strength of 21 to 27 N / mm ² is used, but depending on the load conditions in the finished structure system, high strength concrete with a design standard strength of 30 to 40 N / mm ² should be used. Is preferred. The bar arrangement 16 is arranged in the same manner as a conventional bar arrangement shape in which a predetermined covering is secured following the outer shape. The wall column reinforcement 16a has an amount of reinforcement capable of resisting the bending moment generated in the wall pillar 11d during excavation of the advanced main pit, and the invert 11e includes the continuous portion between the lower lower end of the side wall and the invert end, and The hunting bars 16b and the bottom slab reinforcing bars 16c are arranged in such a manner that the amount of reinforcement that can resist the bending moment at the time of bending and the amount of reinforcement that can resist the punching shear force due to the axial compression force in the completed structure system.

  On the other hand, the installation surface 15 of the leg part 14a of the main arch support is formed on the shoulder 11c of the center pillar. And the bearing steel plate 17 is attached to the installation surface integrally with the concrete main body.

The detailed structure of the bearing steel plate 17 of the shoulder portion 11c of the center pillar will be described with reference to FIGS.
In FIG. 2 (a), a supporting steel plate 17 is attached to the installation surface 15 of the support leg 14 a of the notch portion of the shoulder 11 c of the center pillar 11. In this embodiment, as the bearing steel plate 17, a rolled steel for general structure (SS400) having a thickness of 10 to 20 mm is used. Further, as shown in the figure, the bearing steel plate 17 is formed with a hook 17a bent at a right angle on the rear end side, and a part of the steel plate including the hook 17a portion is embedded in the concrete of the center pillar 11. ing. Further, a base plate 18 is welded to the installation surface 15 of the arch support leg 14 a on the upper surface of the bearing steel plate 17. The base plate 18 has an edge portion 18a slightly bent at both ends upward, and the arch support leg portion 14a is installed on the flat plate portion. In the shoulder portion 11c of the center pillar 11 having such a configuration, the axial compression force transmitted from the arch support leg 14a is dispersed over the entire concrete surface supporting the bearing steel plate 17, and is generated toward the inner side of the main mine. The component force is also canceled by the resistance of the edge portion 18a of the base plate 18 and the hook 17a embedded in the concrete, so that no deviation occurs in the arch support leg portion 14a.

  A modification of the bearing steel plate will be described with reference to FIGS. FIG. 2B shows a modification in which studs 19 are planted on the concrete contact surface of the bearing steel plate 17. By embedding the stud 19 in the concrete in this manner and fixing the bearing steel plate 17 to the shoulder portion 11c, when a surface load is applied to the bearing steel plate 17 by the axial compression force, stress is applied from the steel plate 17 to the stud 19. Disperses and relieves stress concentration in concrete. Also, the resistance to shear slip is greatly improved. It is preferable that a stud having a diameter of about 6 to 10 mm as the stud 19 is previously planted on the lower surface of the bearing steel plate 17 at an appropriate pitch and integrated with the concrete when the concrete is placed.

  FIG. 4C shows that the bearing steel plate 17 having an L-shaped cross section can reliably bear high tensile stress generated in the concrete at the corner of the shoulder 11c, and can prevent adverse effects on the concrete. . Further, the stud 19 disposed at this time effectively functions as a tensile resistance member against the slip of the arch support leg 14a.

  By adopting the above-mentioned various bearing steel plates, it is not necessary to arrange reinforcing bars such as reinforcing bars for reinforcing the shoulder 11c of the center pillar, and the workability of the arranging work is improved.

  In addition, as shown in FIG. 1, as the entire structure of the center pillar 11, when a gap is generated at the top after the concrete is placed in the wall column portion 11 d and the invert 11 e, high strength non-shrink mortar 12 is post-filled. Thus, it is preferable to completely block between the top of the advanced guide shaft and the concrete.

  Hereinafter, in addition to the reinforcing structure of the shoulder portion 11c of the center pillar described above, an embodiment in which the wall pillar portion of the center pillar is a reinforced concrete structure incorporating a reinforcing steel pipe column in the completed structure system will be described. As shown in FIG. 5, in the completed structure system in which the secondary lining of the main mine 20 and 30 is completed as a spectacle tunnel, if the earth covering load on the upper part of the tunnel is large, the shaft to be borne by the center pillar after completion A case where the compression force becomes very large is assumed. In Example 2, assuming such a load state, the center pillar wall column portion 11d is a composite structure including the reinforcing steel pipe column 40 and the reinforced concrete structure described above (FIG. 1). As described above, in this embodiment, the center pillar 11 is designed with a pitch (for example, about 1.5 to 2.5 m) set in the tunnel extension direction in the center pillar 11 as shown in FIG. It consists of a steel pipe column reinforced concrete structure in which the steel pipe column 40 is built. A bearing plate 42 having a predetermined thickness is fixed to the upper and lower ends of the steel pipe column 40 and filled with a concrete concrete 41 having a predetermined strength as a compression structure. The center pillar 11 is filled with the steel pipe column 40. It is possible to reliably bear the soil covering load above the main tunnels 20 and 30 acting on the tunnel. At this time, a non-shrink mortar 43 is filled between the top of the steel pipe column 40 and the support of the central advanced guide shaft so that the axial force transmission to the steel pipe column 40 can be performed smoothly, and both are integrated. ing. The steel pipe column 40 is designed so that its material, outer diameter, wall thickness, filling concrete strength and column pitch are adequate for a properly assumed working load as shown in FIG. 5, for example. It is set to have a sufficient proof stress.

  The reinforced concrete structure part of the center pillar 11 is designed in consideration of the temporary stress state at each construction stage described above and the permanent stress state when the load transmitted from the arch support leg 14a in the completed structure system is borne. Has been. In addition, since the steel pipe pillar 40 can also resist the bending which arises in the wall pillar part 11d of the center pillar 11, the amount of reinforcing bars of the center pillar 11 can be reduced as a whole.

Sectional drawing which showed one Example of the center pillar structure of the spectacles tunnel of this invention. The elements on larger scale which expanded and showed the structure of the shoulder part of the center pillar shown in FIG. Sectional drawing which showed the other Example of the center pillar structure of the spectacles tunnel of this invention. The tunnel sectional view showing an example of the completed shape of the glasses tunnel. Explanatory drawing which showed typically the load and its flow which act on the glasses tunnel shown in FIG. The tunnel sectional view showing an example of the center pillar built in the central advanced guide shaft. The tunnel sectional view which showed an example of the support state to the center pillar of the arch support leg at the time of excavation of an advanced main mine. The elements on larger scale which showed typically the displacement behavior in the arch support leg part and center pillar shoulder part in FIG.

Explanation of symbols

10 Central advanced shaft 11 Center pillar 14 Arch support 17 Bearing steel plate 17a Hook 18 Base plate 19 Stud 20 Advanced main shaft 30 Reverse main shaft 40 Steel pipe column

Claims (5)

  It is provided in advance as a shared support structure in an advanced guide shaft located between two main shafts of a spectacle tunnel constructed in parallel, and supports the arch support legs of the main shaft. It is a center pillar structure that bears the ground load between the pits, and the supporting steel plate that holds the arch support legs on the shoulder supporting the upper half arch support legs of the main mine, A center pillar structure of a spectacle tunnel, part of which is embedded and fixed in concrete via an anchor.   The center pillar structure of an eyeglass tunnel according to claim 1, wherein the anchor is a hook-like portion obtained by bending a rear end of the bearing steel plate.   The center pillar structure of the eyeglass tunnel according to claim 1, wherein the anchor is a plurality of studs planted on a lower surface of the bearing steel plate.   The center pillar structure of the eyeglass tunnel according to claim 1, wherein the bearing steel plate is bent in accordance with the shape of the shoulder portion, and studs are planted on the back side thereof.   It is provided in advance as a shared support structure in an advanced guide shaft located between two main shafts of a spectacle tunnel constructed in parallel, and supports the arch support legs of the main shaft. A center pillar structure that bears a ground load between mine shafts, and an inside-filled concrete steel pipe column is erected in the center pillar at a predetermined interval along the tunnel extending direction, and the upper half of the main mine A bearing steel plate for placing and holding the arch support leg is mounted on a shoulder supporting the arch support leg, and a part of the steel sheet is embedded and fixed in concrete via an anchor. Center-pillar structure of the glasses tunnel.

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