JP2000356095A - Segment structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a segment structure which meets a performance required as an outer shell structure constructed of a number of small-cross-section shield segments, and which further meets the requirements for a reduction in period of construction work and for profitability. SOLUTION: This segment structure comprises main girders 1a, 1b disposed along the transverse direction of a shield tunnel; vertical ribs 2 disposed in the axial direction of the shield tunnel; reinforcement 3 disposed between the vertical ribs 2-2; skin plates 4 surrounding the respective outer peripheries of the main girders 1a, 1b and the vertical ribs 2 in the transverse direction of the shield tunnel; and concrete 5 packed into a space formed by the main girders 1a, 1b, the vertical ribs 2 and the skin plates 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a segment structure.

[0002]

2. Description of the Related Art As a method of constructing a tunnel having a super-large section, assembling a shield segment by excavating with a plurality of small-section shield machines and constructing a shell of a tunnel having a super-large section,
There is a method of constructing a tunnel with a very large section by excavating the inside surrounded by the outer shell. When the segment of the small-section shield forming the outer shell has a rectangular cross-section, it receives a cross-sectional force such as a shearing force and an axial force when the inside of the segment is excavated.

[0003] In order to satisfy this demand, the conventional segment includes a main girder having a large cross-section required as an outer structure,
Used from the assembly stage of the shield tunnel. Tensile steel is used as the main girder steel, and a heavy steel shear connector is provided to increase adhesion to concrete. It has a structure in which many vertical ribs having a large cross section and a large weight are provided orthogonally to the main girder.

[0004] However, this structure has problems in that the assembling work in a narrow working space is difficult, the weight of the segment is large, and the manufacturing cost is high.

The performance required at the stage of constructing the rectangular shield and the performance required for the outer shell of the final super large section tunnel are as follows.

<1> Performance required for shield segment The segment is a structure capable of resisting a bending moment, a shearing force, and an axial force acting in the transverse direction due to a soil pressure load. (FIG. 8) When the shield excavator excavates, the segment receives a propulsion reaction force, so that the segment is a structure capable of resisting the propulsion axial force. The segments are produced separately in the axial and transverse directions of the tunnel and assembled in a small section shielded excavator.
At this time, the assembly can be performed in a short time, and the joint section does not reduce the sectional force against the sectional force.

<2> Performance required as an outer structure of a tunnel A bending moment, a shearing force, and an axial force are integrally formed with concrete placed inside a segment against a soil pressure load or an earthquake load acting on the entire tunnel. Can resist. The steel members of the segments are effectively arranged as tensile members when subjected to the cross-sectional force of the bending moment. In particular, the joint part in the transverse direction does not become a weak part as a tensile material. When assembling as a shield segment, it is impossible to carry out shear reinforcement as an outer structure because of the need to carry in the divided segments and carry out excavated earth and sand. But,
It is necessary to perform shear reinforcement before placing concrete inside the segment, and a reasonable construction method is required for this.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by assembling the divided segments in a short time, and furthermore, the joint portion has the same tensile resistance and rigidity as the general portion other than the joint portion. . The segment must have a structure that can reasonably resist axial force against propulsion reaction force during shield excavation. By reducing the required cross-sectional performance as a shield segment, the cost of manufacturing the segment can be reduced. Have sufficient tensile reinforcement steel required for the shell structure. Before placing concrete inside the segment, the shear reinforcement as the shell structure can be performed in a short time and economically. The purpose of the present invention is to provide a segment structure that can easily and reliably cast concrete inside the segment, is integrated with the segment after casting, and efficiently resists bending moment and shear force as an outer structure. And

[0009]

According to a first aspect of the present invention, a main girder disposed in a transverse direction of a shield tunnel includes a center main girder disposed at the center of a segment and having a reinforcing bar fixed in the same direction inside the segment.
The vertical ribs, which are composed of end main girders arranged in parallel to both ends of the segment and are arranged facing the axial direction of the shield tunnel, have reinforcing bars arranged and fixed between the vertical ribs, and the outer periphery of the main girder and the vertical ribs A segment structure characterized in that a space formed by a main girder, longitudinal ribs, and a skin plate is filled with concrete to be welded by being surrounded by a skin plate in a transverse direction of the shield tunnel. According to a second aspect, in the segment structure according to the first aspect, the inter-ring joining of the segments is provided with a bolt hole in the end main girder in advance, and the mounting pieces are bolted to both sides of the end main girder, and the mounting pieces are joined together. A structure to lock the reinforcing steel for shear reinforcement is used.The compression side joining of the segments is a structure where the end plates are joined together by short bolts.The tensile side joining of the segments is a mortar inside the segment joining end in advance. A box-shaped body of a filled steel plate is provided and joined by a PC steel bar. According to a third invention, in the segment structure according to any one of the first invention and the second invention, the reinforcement of the segment end portion includes a longitudinal rib arranged in the axial direction of the shield tunnel, a middle main girder and an end. A structure that welds to the main girder and the skin plate and protrudes from each main girder to fix the reinforcing steel between the protruding parts of the facing vertical ribs, or a vertical rib arranged in the axial direction of the shield tunnel, A segment structure having the same height as a main girder and having a structure in which a reinforcing bar with a fixing plate is disposed between facing vertical ribs.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

[0011]

FIG. 1 is a perspective view of a divided segment S constituting a part of a segment structure according to the present invention. In the present embodiment, the segment segments S are assembled, for example, vertically and horizontally symmetrically to constitute a segment structure for one ring. Split segment S
Is the main main girder 1a arranged in the transverse direction of the shield tunnel
And an end main girder 1b, a longitudinal rib 2 disposed in the axial direction of the shield tunnel, a reinforcing bar (or a threaded reinforcing bar) 3 disposed between the vertical ribs 2 and 2, the middle main girder 1a, and an end main girder. 1b
And a skin plate 4 surrounding the outer periphery of the vertical rib 2 in the transverse direction of the shield tunnel, and concrete 5 filled in a space formed by the middle main girder 1a, the end main girder 1b, the vertical rib 2 and the skin plate 4. Is done.

<A> Main girder The main girder forming the skeleton of the divided segment 1 is composed of a middle main girder 1a arranged at the center of the segment structure and end main girder 1b arranged at both ends of the segment structure. You. (FIG. 1) In the present embodiment, the middle main girder 1a uses an H-shaped steel, and the end main girder 1b uses a steel flat plate. (Fig. 2) After a plurality of small-section rectangular shields have been completed and the mutual shield tunnels have been joined, before casting concrete 5 inside, before the concrete 5 is cast inside, H-section steel, Reinforcing bars (or threaded reinforcing bars) 3a serving as shear reinforcing bars are fixed between the inner flanges. One end of the reinforcing bar (or the threaded reinforcing bar) 3a is friction-welded to the fixing plate 6, and the other end is fixed by a lock nut 8, for example, with a steel plate 7 interposed therebetween. The reinforcing bar (or threaded bar) 3a is fixed by friction-welding the fixing plate 6 to both ends of the reinforcing bar 3a and fixing the fixing plate 6 between the inner flanges of the facing main girder 1a, or by forming holes at both ends of the reinforcing bar 3a. There is also a method in which the steel plate 7 is inserted and placed between the inner flanges of the facing main main girder 1a and fixed with the lock nut 8.

<B> Joint structure between rings of segments Ring bolt holes 9 are provided at predetermined intervals on the side surface of the end main girder 1b, and joining is performed with ring bolts 10. (FIGS. 1, 2) At the time of bolt joining, a structure in which the attachment pieces 11 are joined to both sides of the end main girder 1b with ring bolts 10, and two pieces of the end main girder 1b and two pieces of the attachment pieces 11 are simultaneously joined. And The mounting piece 11 has a structure in which a reinforcing reinforcing bar 3a is locked by a nut 12 (FIG. 3.a) or a structure in which the reinforcing bar 3a is locked by a U hook (FIG. 3.b).

<C> Segment-to-piece joining structure The shield segment constitutes one ring by assembling segments (divided segments S) one by one in the transverse direction of the tunnel. (In the present embodiment, for example, one ring is constituted by 6 pieces.) As shown in FIG. 8, when excavating the inner mass 15 surrounded by the outer structure 14, the outer structure 14 A large bending moment occurs. Therefore, the joint structure between the pieces of the segments must be an optimum structure according to the magnitude of the sectional force generated in the outer structure 14.

As shown in FIG. 4, the joint structure between the pieces of the divided segment S that becomes the compression side due to the bending moment is the outer structure 1.
As for 4, the joint in the transverse direction is connected to the end plate 17 and the simple short bolt 1 to resist the concrete 5.
Only the structure joined at 6 is sufficient.

On the other hand, as shown in FIG. 5, the inter-piece joint structure of the segment which is brought into the tensile side by the bending moment is a steel plate box 18 in which the mortar 20 is filled at the segment joint end in advance. And a composite structure joined by the PC steel rods 19. With this joining structure, even if the joining between the pieces of the segments is in a tensile state over the entire cross section, the rigidity of the steel plate box 18 filled with the mortar 20 is high, so that the PC steel rod 19 has an even tensile force. By acting, the total number of the PC steel bars 19 at the joint works effectively, and a structure in which the tensile strength is not reduced can be obtained.

<D> Reinforcing Structure at Segment End FIG. 6 is a diagram showing a stress / strain relationship between a PC steel bar and a reinforcing bar. FIG. 7 shows a case where a reinforcing bar is reinforced in addition to the PC steel bar at the joint. FIG. 4 is a diagram showing the deformation characteristics of FIG. The junction of the shield segment in the cross direction of the tunnel is a weak portion because a tensile force acts on the entire cross section. It is necessary to provide a reinforcing structure other than the PC steel bar 19 in the weak portion to increase the tensile rigidity. Therefore, the height of the vertical rib 2 in FIG. 1 is made to protrude from the flanges of the middle main girder 1a and the end main girder 1b, and a fixing hole 21 for inserting the reinforcing bar 3 later and fixing is formed in the protruding portion. Main girder 1
a, welded to the end main girder 1b and the skin plate 4 to fix the reinforcing bar 3 between the projecting portions of the facing vertical ribs 2.
Or, a vertical rib 2 arranged in the axial direction of the shield tunnel
May have the same height as the middle main girder 1a and the end main girder 1b, and the reinforcing bar 3 with the fixing plate may be arranged between the facing vertical ribs 2 and 2. (Not shown) By this structure type, the bending deformation performance as the outer structure 14 (FIG. 8) can be improved as compared with the structure of only the PC steel bar 19 shown in FIG. This means that even if the deformation performance is not required for the constant load due to the water earth pressure,
This is an important reinforcement structure to increase the toughness rate during an earthquake.

[0018]

The operation of the present invention will be described below.

<A> Assembling of the divided segment FIG. 1 is a perspective view of the divided segment S. In the present embodiment, the segment segments S are assembled, for example, vertically and horizontally symmetrically to constitute a segment structure for one ring. Since the divided segment S generates different sectional stresses depending on the arrangement of the compression side and the tension side,
The joining method is different.

As shown in FIG. 4, the joints in the transverse direction need only be joined to the end plate 17 with simple short bolts 16 in order to resist the concrete 5 on the compression side.

On the other hand, as shown in FIG. 5, a box-shaped member 18 made of a steel plate in which mortar 20 is previously filled inside is provided at the end of the segment, as shown in FIG. By joining with the rod 19, a composite structure of the PC steel rod 19 and the mortar 20 is formed. Due to the formation of the joint of the composite structure, the rigidity of the steel plate box 18 filled with the mortar 20 is high even if the joint between the pieces of the segments is in a tensile state over the entire cross section. And the total number of PC steel bars 19 at the joint works effectively to form a joint structure in which the tensile strength does not decrease.

<B> Segment-to-Ring Joining FIG. 3A is a perspective view showing a segment-to-ring joining state. According to the position of the ring bolt hole 9 (FIG. 1), the end pieces 1b to be joined are sandwiched from both sides, and the mounting piece 11 is fastened and fixed by the ring bolt 10 and joined. Since the attachment pieces 11 are installed on all the ring bolts 10, the attachment pieces 11 are respectively installed at the same positions between the rings of the opposing segments.

By fixing the reinforcing bar 3a serving as a shear reinforcing bar by using the opposed mounting pieces 11, the adhesion to the concrete poured into the segment is large, and therefore, the outer structure 14 (FIG. 8). It can disperse oblique shear cracks generated in concrete when working as a shear structural material. The reinforcing bar 3a shown in FIG.
In addition, a reinforcing bar 3a with a U hook 13 shown in FIG.
Can also be used.

Conventional shear connectors are generally composed of main beams 1a and 1b and skin plates 4 at angles or plates.
, Which requires about 30 to 40% of the weight of the steel material of the segment, and the manufacturing cost is high.

On the other hand, since the reinforcing bar 3 is fixed to the nut 12 by the vertical rib 2, the vertical rib 2 and the main girder 1a,
Since the concrete surrounded by 1b can resist shearing shear with the main girders 1a and 1b, it is not necessary to provide a shear connector which is conventionally required.

<C> Excavation of the small-section shield excavator As described above, after the assembly of the divided segments and the joining operation between the rings of the segments are completed, the excavation work and the propulsion work are performed by the small-section shield excavator. Since the propulsion reaction force when the shield excavator is propelled works on all of the already assembled segments, the axial force resistance of the segments must be sufficiently strong.

In the conventional steel shell segment, a number of vertical ribs are provided orthogonally to the main girder to cope with the axial force resistance. The longitudinal ribs are steel and require reinforcement by steel to avoid buckling against compressive axial forces, which has made the segments expensive.

In the segment of the present invention shown in FIGS. 1 to 5, concrete 5 is previously cast on the skin plate 4 side, and the compression ribs resist the propulsion reaction force. And not. Therefore, a vertical rib having a large cross section is not required, and an inexpensive segment can be formed.

[0029]

Since the present invention has been described above,
The following effects can be obtained. <B> The cross section of the main girder of the segment is minimized, and the tensile material finally required as the outer structure has a structure in which reinforcing bars are arranged in advance. It can function effectively as a tensile material. <B> For the same reason, the manufacturing cost can be reduced. <C> Since the reinforcing bars are arranged in the main girder direction in advance, the adhesion to concrete is large, and the conventionally required shear connector is not required, and the weight of the steel material of the segment and the manufacturing cost can be reduced. <D> For the same reason, complicated rebar assembling work can be omitted even in a narrow shield internal space, and efficient work can be performed. <E> Since concrete is cast in advance on the skin plate side of the segment, it resists the propulsion reaction force due to the compressive axial force of the concrete, so there is no need to reinforce the vertical ribs with steel. <F> As a structure for joining the segments on the tensile side in the transverse direction, a box-shaped body is formed at the joint end and mortar is filled inside, so it has high rigidity and works on the PC steel rod of the joint steel material Since the tensile force can be made uniform and the composite structure of the steel plate and the filling mortar is used, a structure with low cost and high rigidity can be obtained. <G> In addition to the joining using the PC steel rods, the structure in which the opposing longitudinal ribs are joined by a reinforcing bar can improve the deformation performance after the maximum resistance bending moment. This is important for increasing the toughness ratio during an earthquake.

[Brief description of the drawings]

FIG. 1 is a perspective view of a split segment according to the present invention.

FIG. 2 is a perspective view showing a configuration of a main girder.

FIG. 3 is a diagram showing a state in which a joint structure between rings and a reinforcing bar for shear reinforcement are attached.

FIG. 4 is a diagram showing a joining structure between pieces of a compression-side divided segment.

FIG. 5 is a diagram showing a joining structure between pieces of a tension side divided segment.

FIG. 6 is a diagram showing a stress / strain relationship between a PC steel rod and a reinforcing bar.

FIG. 7 is a view showing deformation characteristics when a reinforcing steel bar is reinforced in addition to the PC steel bar at the joint.

FIG. 8 is a diagram showing stresses acting on the outer structure.

Claims (3)

[Claims] 1. A main girder arranged in the transverse direction of a shield tunnel includes a middle main girder disposed in the center of a segment and having a reinforcing bar fixed in the same direction inside, and an end main girder disposed in parallel with both ends of the segment. Vertical ribs to be disposed facing the shield tunnel in the axial direction are arranged and fixed with reinforcing steel between the vertical ribs, and the outer periphery of the main girder and the vertical ribs are surrounded by skin plates in the transverse direction of the shield tunnel. A segment structure, which is formed by welding and filling a space formed by a main girder, a longitudinal rib, and a skin plate with concrete. 2. The segment structure according to claim 1, wherein the rings between the segments are joined by providing a bolt hole in the end main girder in advance, connecting the mounting pieces with bolts on both sides of the end main girder, and shearing the mounting pieces. The structure to lock the reinforcing steel is used.The compression side joining of the segments is made by joining the end plates with short bolts.The segment joining end is filled with mortar inside the segment joining end in advance. A segment structure, wherein a box-shaped body of a steel plate is provided and joined by a PC steel bar. 3. The segment structure according to claim 1, wherein the reinforcing of the segment ends is performed by forming longitudinal ribs arranged in the axial direction of the shield tunnel into a middle main girder, an end main girder, and an end main girder. A structure that welds to the skin plate and protrudes from each main girder to fix the reinforcing bar between the protruding parts of the facing vertical ribs, or a vertical rib arranged in the axial direction of the shield tunnel,
A segment structure having the same height as a middle main girder and an end main girder, and having a structure in which a reinforcing bar with a fixing plate is arranged between vertical ribs facing each other.