JP2020063570A - Precast floor slab, precast floor slab structure and construction method thereof - Google Patents

Abstract

To provide a precast floor slab capable of being placed at a bottom portion of a tunnel in a stable and rattle-free state unneeded to be filled with a filling material that needs curing, and a tunnel floor slab structure and a construction method thereof.SOLUTION: A precast floor slab 2 is arranged at a bottom portion of a tunnel T, and includes a convex projection 23 on floor slab lower surface portions 22, 22 formed along the shape of the bottom portion of the tunnel T. In a tunnel floor slab structure and a construction method thereof, the convex projection 23 is placed to a center portion of the precast floor slab 2, and each of support members 3, 3 is disposed into each gap between each end of the precast floor slab 2 and the bottom portion of the tunnel T.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a precast floor slab arranged at the bottom of a tunnel, a tunnel floor slab structure, and a method for constructing the same.

In recent years, mainly in the Tokyo metropolitan area, construction of expressways and railway networks utilizing deep underground spaces in urban areas has been actively carried out.
Many of the main line tunnels are the largest large-section long-distance shield tunnels in the world, and the construction requires high-speed construction technology as well as advanced technology that enables large-section long-distance construction.
Precast products have been positively incorporated into various concrete members in order to increase the speed. For example, in road tunnels, the use of half-precast type synthetic slabs for road slabs is becoming common.
As for the invert placed at the bottom of the tunnel, conventionally, in-situ concrete and fluidized soil that reuses excavated residual soil have been used for on-site construction. Since it is used for multiple purposes at the time of temporary construction such as battery locomotive rails for loading and unloading materials and materials, vehicle passageways such as dump trucks, it is desirable that the construction is completed at the very early stage of the cycle time. In the construction of the department, application of precast products has started.

Patent Document 1 discloses a method for constructing an invert that is composed of a plurality of concrete precast inverts at the bottom of a tunnel. A floor slab consisting of a plurality of precast slabs is constructed in the middle part of the invert, and a middle wall consisting of a plurality of precast concrete inner walls is constructed between the precast invert and the precast slab.
The precast inverts are laid on the bottom of the tunnel adjacent to each other in the axial direction of the tunnel, and each precast invert is fixed to the segment by a plurality of anchor bolts. The anchor bolts simultaneously adjust the level of each precast invert, and the adjustment mortar is filled between the adjusted precast inverts and the segments. The lower end surface of the precast invert is formed in a convex curved shape along the inner peripheral surface of the segment.
When temporarily using the upper surface of the precast invert, the precast invert is supported only by the anchor bolts located near the end of the precast invert, and the load of the temporary equipment etc. is applied while maintaining the state of floating from the inner peripheral surface of the segment. It is structurally difficult and unrealistic (Usually, Invert, which does not assume bending when used in the main installation, does not have bending resistance as a bending member. Only to counter the bending that occurs during temporary installation. It is unreasonable to arrange excessive rebar.) Therefore, it is considerable that the mortar filled in the gap formed between the precast invert and the inner peripheral surface of the segment is used after being hardened to a predetermined strength.
However, when filling the mortar after placing the precast invert, a curing period is required until the mortar develops a predetermined strength, and because the gap is narrow, poor filling is likely to occur and priority is given to filling properties. If the injection pressure of the mortar is increased, it is possible that the pressure causes an unbalanced load to act on the precast invert, causing damage, or it may fluctuate from the position where the mortar is installed.

JP, 2008-127834, A

The present invention has been made in view of such circumstances, pre-cast floor slab that can be placed in the tunnel bottom part pre-cast floor slab in the state without the need for the filling of the filler necessary for curing, stable rattling, A slab structure and a construction method thereof.

  In order to solve the above-mentioned problems, the precast floor slab of the present invention is provided at the bottom of the tunnel, and has a convex convex portion on the bottom surface of the floor slab formed along the shape of the bottom of the tunnel. It is preferable that the convex portion is provided in a central portion of the precast floor slab.

  In the floor slab structure of the tunnel of the present invention, a support member is disposed in a gap between both ends of the precast floor slab and the tunnel bottom in a state where the precast floor slab is disposed at the tunnel bottom. Is characterized by. It is desirable that a shift prevention member fixed to the bottom of the tunnel is disposed on the side surface of the support member.

  The method for constructing a floor slab structure for a tunnel according to the present invention comprises: placing a precast floor slab having a convex portion on the lower surface of the floor slab formed along the shape of the tunnel bottom at the bottom of the tunnel; The support member is arranged in a gap between both ends of the tunnel and the bottom of the tunnel.

According to the precast floor slab of the present invention, since the convex portion having the convex shape is provided on the lower surface side formed along the shape of the inner peripheral surface of the bottom surface of the tunnel to be installed, the lateral earth pressure is more than the vertical earth pressure. Even if the inner peripheral surface of the tunnel bottom surface is crushed vertically due to an unbalanced load, the convex portion can reliably catch the tunnel bottom surface. Therefore, it is possible to avoid damage to the precast floor slab due to excessive bending moment or shearing force, without applying a heavy load.
Further, as described above, when the tunnel is vertically crushed, both ends of the precast floor slab come into contact with the inner surface of the tunnel in advance, so that it is assumed that a bending moment is generated with the both ends of the precast floor slab as fulcrums. However, if a convex part is provided at the center of the precast floor slab where the maximum bending moment occurs, it means that a fulcrum will be provided at the center of the beam with the precast floor slab as a simple beam preceding both ends. The generated bending moment can be relaxed to a small extent.

According to the floor slab structure for a tunnel of the present invention, even if a gap is formed between the both ends of the precast floor slab and the tunnel bottom due to the convex portion of the precast floor slab, the support member is arranged in the gap. Thus, since the precast floor slab does not become a balance and support points can be secured at both ends, a stable floor slab structure can be achieved.
Further, if the shift prevention member fixed to the bottom of the tunnel is arranged on the side surface of the support member, the support member loosens out of the gap even when subjected to vibration or repeated load of the vehicle or the like acting on the precast structure. And can maintain a stable structure permanently.

  According to the method for constructing the tunnel floor slab structure of the present invention, the support member is arranged in the gap between the both ends of the precast floor slab and the tunnel bottom portion caused by the convex portion provided on the floor slab lower surface of the precast floor slab. By doing so, it is possible to flexibly deal with the deformation due to the external load of the tunnel, the misalignment and opening of the segment, the manufacturing error, etc., and it is possible to maintain a stable floor slab structure without rattling.

It is sectional drawing of the precast floor slab and floor slab structure of this invention. It is sectional drawing of the precast floor slab edge part of this invention (A part detail drawing of FIG. 1). It is sectional drawing of the precast floor slab and floor slab structure integrated with the culvert of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
<Precast floor slab and tunnel floor slab structure>
FIG. 1 shows a cross-sectional view of the precast floor slab and floor slab structure of the present invention.
The tunnel T in the present embodiment is a circular shield tunnel, and is formed in a ring shape by combining a plurality of segments S, S ... The segment S is either an RC segment (reinforced concrete segment) having a smooth inner surface or a synthetic segment (filled concrete steel segment).
The precast floor slab 2 is formed in a bowl shape and has a floor slab upper surface portion 21 which is a smooth surface on the upper surface, floor slab lower surface portions 22 and 22 which are curved surfaces on the lower surface, and a convex portion having a convex shape on the lowermost surface. 23 and.
The curvature of the floor slab lower surface portion 22 is formed along the shape of the inner peripheral surface of the bottom portion of the tunnel T which is the installation range. Here, the shape of the inner peripheral surface of the tunnel T corresponds to the case where the tunnel T is assembled into an ideal perfect circle.
Further, the convex portion 23 also has a curvature similar to that of the floor slab lower surface portion 22, but considering the deformation of the tunnel assumed in design, the manufacturing and construction errors of the segments S, S ... The curvature may be changed, and a rubber plate (not shown) is interposed on the lower surface of the convex portion 23 to prevent local stress concentration on the precast floor slab 2 and to adjust the height of the rubber plate. You may use.
The thickness of the convex portion 23 may be arranged at any position in the tunnel T-axis direction in consideration of the deformation of the tunnel, the manufacturing and construction errors of the segments S, S ... It is designed and planned so that both ends of the plate 2 do not come into contact with the inner surface of the segment S forming the tunnel T prior to the convex portion 23.

FIG. 2 shows a cross-sectional view of the end portion of the precast floor slab, which is a detail of part A in FIG.
The gap between the tunnel T and both ends of the precast floor slab 2 caused by the contact between the convex portion 23 and the tunnel T fits the support members 3 and 3 processed according to the size of the gap. Both ends of the precast floor slab 2 are provided with taper portions 24 and 24 so as not to be damaged by contact with the inner surface of the tunnel T, and the support members 3 and 3 are tapered surfaces of the taper portions 24 and 24. By being driven along, the precast floor slab 2 is installed on the bottom surface of the tunnel T in a stable state without rattling. The support member 3 is provided with a taper so as to form a wedge in the insertion direction. The material is not limited as long as it is a material that can be deformed within the elastic range with respect to a future load acting on the floor slab upper surface 21, but steel is used in the embodiment.
In order to prevent the fitted support members 3 and 3 from coming off due to slackness due to repeated loading of load, etc., shift prevention members 4 and 4 are arranged on the side surfaces of the support members 3 and 3, respectively. The slip-prevention member 4 is attached to the insert provided in the segment S through the reaction force member 41 using the L-shaped steel material and the through hole (not shown) provided in the surface of the reaction force member 41 on the segment S side. On the other hand, they are integrally fixed by bolts 42, and finally the floor slab structure 1 of the tunnel is formed.

FIG. 3 shows a cross-sectional view of the precast floor slab integrated with the culvert and the floor slab structure.
In particular, in a highway tunnel or the like, there is a form in which a culvert is provided in the lower space of the road slab and is used as an emergency evacuation passage in the event of a fire. In this embodiment, the precast slab 1 that also serves as the slab of the culvert is used. 1 illustrates one embodiment.

<Construction method of floor slab structure of tunnel>
1 to 3, the method for constructing the floor slab structure of the tunnel according to the embodiment of the present invention is configured such that the convex ridges 23 are formed on the floor slab lower surface portions 22, 22 formed along the shape of the bottom of the tunnel T. The provided precast floor slab 2 is placed at the bottom of the tunnel T, and the support members 3, 3 are placed in the gap between both ends of the precast floor slab 2 and the bottom of the tunnel T.
The precast floor slab 1 is arranged at the bottom of a predetermined tunnel T by a toothed loader (not shown) arranged in the tunnel T tunnel. The height of the precast floor slab 1 may be adjusted by interposing a plurality of rubber plates (not shown) on the lower surface of the convex portion 23.
The support members 3 and 3 are inserted and fitted in the insertion direction using a hammer or the like.
Then, in the fitted state, the shift preventing members are arranged on the side surfaces of the supporting members 3 and 3. The slip-prevention member 4 is attached to the insert provided in the segment S through the reaction force member 41 using the L-shaped steel material and the through hole (not shown) provided in the surface of the reaction force member 41 on the segment S side. On the other hand, they are integrally fixed by bolts 42, and finally the floor slab structure 1 of the tunnel is formed.

According to the embodiment of the precast floor slab of the present invention, since the convex portion of the convex shape is provided on the lower surface side formed along the shape of the inner peripheral surface of the bottom surface of the tunnel to be installed, it is more than the vertical earth pressure side. Even if the inner circumferential surface of the tunnel bottom surface is crushed vertically due to predominantly biased earth pressure, the convex portion can reliably catch the tunnel bottom surface, so the precast floor slab It is possible to prevent the precast floor slab from being damaged by an excessive bending moment or shearing force being applied to the precast floor slab.
Further, as described above, when the tunnel is vertically crushed, both ends of the precast floor slab come into contact with the inner surface of the tunnel in advance, so that it is assumed that a bending moment is generated with the both ends of the precast floor slab as fulcrums. However, if a convex part is provided at the center of the precast floor slab where the maximum bending moment occurs, it means that a fulcrum will be provided at the center of the beam with the precast floor slab as a simple beam preceding both ends. The generated bending moment can be relaxed to a small extent.

According to the embodiment of the floor slab structure for a tunnel of the present invention, even if a gap is formed between both ends of the precast floor slab and the tunnel bottom due to the convex portion of the precast floor slab, the support member is arranged in the gap. By doing so, the precast floor slab does not become a balance, and since support points can be secured at both ends, a stable floor slab structure can be achieved.
Further, if the shift prevention member fixed to the bottom of the tunnel is arranged on the side surface of the support member, the support member loosens out of the gap even when subjected to vibration or repeated load of the vehicle or the like acting on the precast structure. And can maintain a stable structure permanently.

  According to the embodiment of the method for constructing the tunnel floor slab structure of the present invention, the support member is provided in the gap between the both ends of the precast floor slab and the tunnel bottom caused by the convex portion provided on the floor slab lower surface of the precast floor slab. By arranging, it is possible to flexibly deal with deformation due to the external load of the tunnel, misalignment and opening of segments, manufacturing error, etc., and it is possible to maintain a stable floor slab structure without rattling.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be appropriately modified without departing from the spirit of the present invention.
For example, the convex portion of the precast floor slab is not limited to one in the central portion, and there may be a plurality of convex portions. Further, the target to which the precast floor slab is applied is not limited to the RC segment and the composite segment, and may be a segment such as a steel segment whose inner space surface side is not smooth. In this case, after placing the precast floor slab on the bottom of the tunnel, a gap between the precast floor slab and the segment forming the tunnel is filled with a filler such as mortar.

T Tunnel S Segment 1 Tunnel floor slab structure 2 Precast floor slab 21 Floor slab upper surface 22 Floor slab lower surface 23 Convex portion 24 Tapered portion 3 Support member 4 Shift prevention member 41 Reaction force member 42 Bolt

Claims (5)

  A precast floor slab arranged on the bottom of a tunnel, having a convex portion on the lower surface of the floor slab formed along the shape of the bottom of the tunnel.   The precast floor slab according to claim 1, wherein the convex portion is provided in a central portion of the precast floor slab.   The support member is arranged in a gap between both ends of the precast floor slab and the tunnel bottom in a state where the precast floor slab is arranged in the tunnel bottom. The floor slab structure of the tunnel described in 2.   The floor slab structure for a tunnel according to claim 3, wherein a shift preventing member fixed to a bottom portion of the tunnel is disposed on a side surface of the supporting member. A precast floor slab provided with a convex portion on the lower surface of the floor slab formed along the shape of the tunnel bottom is arranged at the bottom of the tunnel.
A method for constructing a floor slab structure for a tunnel, characterized in that support members are arranged in a gap between both ends of the precast floor slab and the bottom of the tunnel.

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