JP2003161098A - Segment for tunnel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a segment capable of satisfying the conditions of connecting locations in the direction of a tunnel axis and halving the number of connecting bolts for locations of reduced strength conditions without reducing strength or increasing the number of types. <P>SOLUTION: A curved face 1a in the direction of the tunnel axis is provided with bolt holes 4 at regular intervals in its circumferential direction. The internal between the bolt hole 4 at one end in the circumferential direction and one face 1b in the circumferential direction and the interval between the bolt hole 4 at the other end in the circumferential direction and the other face 1b in the circumferential direction are each set equally to half the interval between adjacent bolt holes 4, horizontal ribs 1f extended between the faces 1a in the axial direction are provided at regular intervals in the circumferential direction. The interval w1 between a rib part 1F at one end in the circumferential direction and the one face 1b in the circumferential direction and the interval w2 between the rib part 1F at the other end in the circumferential direction and the other face 1b in the circumferential direction are each set equally to half the interval between adjacent rib parts 1f and 1f. The interval between the adjacent rib parts 1f and 1f is set smaller than the interval between the adjacent bolt holes 4 and 4. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tunnel segment for forming a tunnel inner wall by arranging a plurality of tunnel circumferential directions and tunnel axial directions to be connected to each other. The present invention relates to a technology for reasonably reducing the number of connecting portions between segments when used.

[0002]

2. Description of the Related Art As a conventional segment, for example, one shown in Japanese Patent Laid-Open No. 9-158687 (see FIG. 1) is known. That is, as shown in FIGS. 18 (a) and 18 (b), the main body frame 1 made of ductile cast iron and a large number of inflow solidified in the central portion in the tunnel axial direction [direction perpendicular to the paper surface in FIG. 18 (a)]. A segment S is composed of the concrete portion 15. A large number of segments S
A ring-shaped tunnel ring TR (see FIG. 1) can be formed by connecting and integrating the bolts and nuts in both the axial direction of the tunnel and the circumferential direction of the tunnel.

The main body frame 1 is formed on substantially arc-shaped axial end faces 1a and 1a which are end faces in the tunnel axial direction, circumferential end faces 1b and 1b which are end faces in the tunnel circumferential direction, and both ends in the axial direction of the tunnel. Pair of outer peripheral surfaces 1c, 1c, a single inner peripheral surface 1d formed in the central portion in the axial direction of the tunnel, and a substantially arcuate intermediate connecting the inner peripheral surface 1d and each outer peripheral surface 1c, 1c It has vertical surfaces 1e, 1e and a large number of reinforcing ribs 1f extending in the tunnel axial direction so as to extend between the axial end surfaces 1a, 1a. The concrete part 15 includes a pair of intermediate vertical surfaces 1.
e, 1e, inner peripheral surface 1d, and adjacent reinforcing ribs 1f, 1f
Alternatively, it is filled in the space surrounded by the five faces of the reinforcing rib 1f and the circumferential end face 1b.

On each of the circumferential end faces 1b, 1b, there are formed holes 3 for inserting connecting bolts at a total of 8 places at each of the tunnel axial end portions, and at the same time, each axial end face 1a, 1b is formed.
A hole 4 for inserting a connecting bolt is formed between the adjacent reinforcing ribs 1f, 1f in the la 1a (in this example, the hole 4 is 10
Location).

[0005]

[Problems to be Solved by the Invention] The tunnel segment has sufficient strength and strength to withstand earth pressure in the ground.
It is configured with rigidity and has a large number of bolts to ensure sufficient connection strength with other segments.
I used to use nuts. Particularly, in the tunnel circumferential direction, the bolt holes 4 were provided for each reinforcing rib.

The above-mentioned number of bolts and nuts are set according to the most severe conditions in terms of strength, such as deep depth and sandy land. It was over-equipped under the condition that did not work very strongly. Therefore, as a specification to be used in such a place where the earth pressure is relatively light, it is planned to reduce the number of connecting bolts by half, improve the work efficiency by reducing the labor of bolt fastening operation, and reduce the cost by reducing the number of parts.

Therefore, the conventional segment S shown in FIG.
Although the 10 bolt holes 4 at 10 locations are halved to 5, the simple reduction of one bolt hole 4 as shown in FIG. 19 is not convenient. That is, in the tunnel segment, it is an essential condition (details will be described later) to provide the bolt holes 4 at positions that are axisymmetric in the tunnel circumferential direction so that the soil pressure can be effectively countered. With the bolt number halving structure shown in FIG.
This is because the bolt holes 4 are arranged at positions asymmetrical in the circumferential direction of the tunnel as the segment S.

That is, as shown in FIG. 19, when the angular pitch of the adjacent bolt holes 4 and 4 is P, one circumferential end face 1 is formed.
The angle pitch between b and the first bolt hole 4 is 1
/ 4P, and the angular pitch between the other circumferential end surface 1b and the first bolt hole 4 is 3 / 4P, and the arrangement structure of the bolt holes 4 is clearly deviated.

An object of the present invention is to meet the constraint condition of the connecting bolt position in the axial direction of the tunnel, and to prevent the strength of the segment from decreasing and the number of types of the segment to increase, but for a place where the earth pressure condition is relatively loose. The point is to provide a tunnel segment with a reduced number of connecting bolts.

[0010]

[Structure] The structure according to claim 1 is for use in a tunnel for forming an inner wall of a tunnel by arranging a plurality of them in the circumferential direction of the tunnel and in the axial direction of the tunnel and connecting them, as illustrated in FIG. In the segment, the substantially circular arc-shaped end face 1a is provided with connecting portions R for connecting adjacent segments in the tunnel axial direction at equal intervals in the tunnel circumferential direction on the tunnel axial end face 1a. The connecting portion R of the connecting portion R located at one end in the tunnel circumferential direction and the first connecting portion R at one end in the tunnel circumferential direction
Both the distance from the connecting end surface 1b and the distance between the connecting portion R of the connecting portion R located at the other end in the tunnel circumferential direction and the second connecting end surface 1b at the other end in the tunnel circumferential direction are adjacent to each other. Set it to a value equal to or almost equal to half the interval between them,
Ribs 1f extending in the tunnel axial direction across the pair of tunnel axial end faces 1a are provided at equal intervals in the tunnel circumferential direction, and ribs located at one end in the tunnel circumferential direction of the ribs 1f. The first interval w1 between the portion 1F and the first connecting end face 1b, and the rib portion 1F and the second connecting end face 1b located at the other end of the rib portion 1f in the tunnel circumferential direction.
And the second distance w2 between the adjacent rib portions 1f and 1f are set to be equal to each other at a distance equal to or less than the distance between the adjacent rib portions 1f and 1f, and the rib portions 1f and 1f adjacent to each other than the distance between the adjacent coupling portions R and R are set.
The feature is that the interval between them is set to be small.

The constitution of claim 2 is as shown in FIG.
In the configuration of claim 1, the first interval w1 and the second interval w
2 is set to a value which is half or almost half of the distance between the adjacent rib portions, and the distance between the connecting portions R and R is set to a value twice the distance between the rib portions 1f and 1f. It is characterized by being.

As mentioned above, the reference numerals are given for the sake of convenience in comparison with the drawings, but the present invention is not limited to the configuration of the accompanying drawings by the entry.

[Operation] According to the structure of claim 1, the following operation is achieved. First, the necessity of providing the bolt holes for connecting the segments in the tunnel axial direction in line symmetry in the tunnel circumferential direction will be described. As shown in FIG. 19, when the bolt holes 4 are simply halved to five, the first bolt connection regarding the connection surface x with the adjacent segment S in the tunnel circumferential direction (that is, the end surface 1b in the tunnel circumferential direction of the segment S). The distance in the tunnel circumferential direction to the location, that is, the tunnel radial direction angles d1 and d2 are greatly different (d1 <
d2).

When earth pressure f acts in this state, as shown in FIG. 17, in the first segment S1 on the side where the distance from the connecting surface x to the connecting bolt rb is long, the segment end portion tends to largely bend ( The second segment S on the side where the distance from the connection surface x to the connecting bolt rb is short with respect to
In the case of No. 2, since it hardly bends, both segments S
Therefore, a clear shearing force will act on the connection bolt sb between the circumferential end faces 1b of 1 and S2. This is an unfavorable state in which the strength balance of the segment S cannot be evenly distributed in the tunnel circumferential direction. Therefore, in order to balance the strength of the left and right, the plurality of bolt holes 4 are provided in the tunnel circumference as a single segment S. It needs to be provided symmetrically with respect to the normal line y passing through the center of the direction.

In addition, when considering as a tunnel ring formed by connecting the segments in the tunnel circumferential direction, it is necessary to make the pitch of the connecting bolts for connecting the segments in the tunnel axial direction uniform in the tunnel circumferential direction in terms of strength balance. Therefore, as a result, “equipped with connecting portions for connecting adjacent segments in the tunnel axial direction at equal intervals in the tunnel circumferential direction on the end face in the tunnel axial direction, one end of these connecting portions in the tunnel circumferential direction is provided. And a distance between the connecting portion located at the other end in the tunnel circumferential direction and a second connecting end surface at the other end in the tunnel circumferential direction of the connecting portion. Both of them are set to a value equal to or approximately equal to half the distance between adjacent connecting portions. "

On the other hand, a plurality of rib portions extending in the tunnel axis direction are required to be provided symmetrically with respect to the above-mentioned normal line in view of strength balance as a single segment, and are connecting portions between segments. It is preferable that the end portions in the circumferential direction of the tunnel have increased strength and rigidity, but it is attempted to avoid lowering them. Therefore, the distance between the end face 1b in the circumferential direction and the rib portion 1f adjacent to the end face 1b is 1f,
It should be set below the interval of f. That is, “a first interval between the rib portion located at one end in the tunnel circumferential direction of the plurality of rib portions and the first connection end face, and a rib portion located at the other end in the tunnel circumferential direction of the rib portion and the second connection The second distance from the end face is set to a value equal to or less than the distance between the adjacent rib portions, and the distance between the adjacent rib portions is set smaller than the distance between the adjacent connecting portions. " It is desirable.

By satisfying the above conditions and adopting a configuration in which "the distance between adjacent rib portions is set smaller than the distance between adjacent connecting portions", a segment and a tunnel are formed. It is possible to reduce the number of connecting portions acting in the tunnel axis direction as compared with the conventional one, while making the necessary strength and strength balance suitable. It is also preferable that the segments are symmetrical with respect to the normal in the tunnel circumferential direction, the adjacent segments may be the same, and the number of types of segments does not increase.

According to the structure of claim 2, the first interval and the second interval, that is, the circumferential end face 1b and the rib portion 1 adjacent to the end face 1b.
It is convenient when an odd number of connecting parts is set because the interval with f is set to half or almost half of the interval between adjacent rib parts and the connecting part interval is twice the rib interval. It will be That is, in the case of providing an odd number of connecting portions, in order to satisfy the above-mentioned condition that "the connecting portions are provided symmetrically with respect to the normal line y passing through the center of the tunnel circumferential direction as a single segment S", The connecting part in the middle of the number is arranged exactly in the center in the circumferential direction of the tunnel.

Since the distance between the connecting portions is twice as large as the distance between the rib portions, the connecting portion exists just for every two ribs skipped, and the distance between the circumferential end face and the rib portion adjacent to the end face in the circumferential direction. Is half the distance between adjacent rib portions, so that any connecting portion is located exactly in the center of the adjacent rib portions, and the arrangement balance between the rib portion and the connecting portion is good, and It is possible to obtain a segment having a shape symmetrical to the line (see FIG. 2).

[Effect] In the tunnel segment according to the first aspect, the required strength as a segment, the strength balance in the tunnel circumferential direction, and the strength balance at the segment connecting points in the tunnel circumferential direction are sufficient. However, it was possible to reduce the number of connecting parts acting in the tunnel axis direction, and for that reason, the number of types of segments did not increase, which made it rational.

According to the second aspect of the present invention, in addition to the effect of the first aspect, the tunnel segment has a number of connecting portions while maintaining an extremely preferable strength balance and shape balance even though it has an odd number of connecting portions. There is an advantage that can be reduced.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a tunnel ring TR constructed by using the tunnel segments SA, SB and SK according to the present invention, and FIG. 2 shows a standard specification A segment SA.
Are shown respectively. A single unit tunnel ring tr in the tunnel axis direction (arrow A direction) has one K type segment SK among these three types of segments SA, SB, SK, and A type and B type segments SA, SB. A total of 5 segments, 2 each, in the tunnel circumferential direction (arrow B direction)
It is configured by connecting to.

The A-type segment SA has a symmetrical shape in both the circumferential direction and the axial direction of the tunnel, and the total length angle in the circumferential direction is set to 85.714 degrees. The B-type segment SA is basically the same as the A-type segment SA, but by moving the K-type segment SK from the inner diameter side to the outer diameter side (see FIG. 1), a pair of B-type segments S is formed.
For convenience of pushing and setting between B and SB, only one difference is that the circumferential end surface 2b in the one circumferential direction of the tunnel is inclined in the direction in which the inner diameter side is narrowed with respect to the radial line (FIG. 6).
reference).

The K-shaped segment SK has a short basic angle in the tunnel circumferential direction of 17.143 degrees, and both circumferential end faces 5b and 5b thereof are inclined opposite to the circumferential end face 2b of the B-shaped segment SB. Is applied (see FIG. 7). Each of the segments S (SA, SB, SK) is made of cast ductile cast iron, and the structure thereof will be described from the basic type A segment SA.

-Regarding the A-type segment SA-As shown in FIGS. 2 to 5, the A-type segment SA has substantially arc-shaped axial end faces 1a, 1 which are end faces in the tunnel axial direction.
a and circumferential end faces 1b, 1 which are end faces in the circumferential direction of the tunnel.
b, an outer peripheral surface 1c, two vertical ribs 1g and 1g having substantially the same shape as the axial end surface 1a, and a large number of horizontal ribs (an example of a rib portion) 1f extending in the tunnel axial direction. It is made up of things.

The axial end faces 1a, 1a are provided with first bolt holes 4 (an example of a connecting portion R) for connecting bolts and nuts of adjacent segments in the tunnel axial direction at an equal angle D [about] in the tunnel circumferential direction. 17.143 degrees (1/5 of the overall angle of the A-type segment SA)] are formed at a total of 5 locations, and the circumferential end faces 1b and 1b are connected to adjacent segments in the tunnel circumferential direction by bolts and nuts. 2 second bolt holes 3 for the total of 4 bolts, 2 at each end in the axial direction of the tunnel.
It is formed in the place.

The lateral ribs 1f are formed so as to be unified in a direction parallel to the normal line Z passing through the center of the tunnel SA in the segment SA, which is convenient in the die cutting direction during casting. The reference position for arranging the lateral ribs 1f at equal angles in the tunnel circumferential direction is the tip position of the lateral ribs 1f. That is, the center point Y is a reference point in the width direction of the tip of the lateral rib 1f, and the center points Y are arranged at equal angles d [about 8.571 degrees (1/10 of the entire angle of the A-type segment SA)]. There is.

However, the first and second angles w1 and w2 between the pair of lateral ribs 1F and 1F located at the end in the circumferential direction of the tunnel and the circumferential end face 1b are the angles (8 between the adjacent lateral ribs 1f and 1f). It is set to about 4.286 degrees, which is exactly half the value of 0.571 degrees). Due to the relationship between the shape of the circumferential end surface 1b and the die cutting direction, the space between the lateral ribs 1F and the circumferential end surface 1b is formed by a sand mold. 2 and 4, the heights of the lateral ribs 1F, 1F are
Except for the points of intersection with the axial end faces 1a, 1a and the vertical ribs 1g, 1g, the height is made low so that sand can be taken in and out easily.

In addition, the rib thicknesses at the four positions of the end lateral ribs 1F, 1F and the lateral ribs 1f, 1f adjacent thereto are thicker than the other lateral ribs 1f (17 mm at the tip) (end lateral rib 1F). Is 28.5 mm at the tip, and the adjacent lateral rib 1f is 27 mm at the tip) for reinforcement. And the circumferential end surface 1
The walls b and 1b are also thickened (25 mm) and reinforced.
Further, both axial end faces 1a, 1a and both circumferential end faces 1b, 1
On four sides of b, two-stage sealing grooves 11 and 12 for filling a sealing material are formed to fill a gap between adjacent segments.

The circumferential angle D (one pitch angle) between the adjacent first bolt holes 4 at the five locations is the lateral ribs 1f, 1
It is set to 17.143 degrees, which is twice the circumferential angle between f,
The circumferential angle between the circumferential end surface 1a and the adjacent first bolt hole 4 is 8.57, which is the same as the angle between the lateral ribs 1f and 1f.
It is set to 1 degree (1/2 pitch angle). That is,
Angularly, the first bolt holes 4 have adjacent horizontal ribs 1f, 1f.
It is located exactly in the center of the space and the horizontal ribs 1f, 1f
It is regularly arranged at twice the pitch. Around the first bolt hole 4, a thick wall portion 6 is formed in order to reinforce this portion along the die cutting direction.

The horizontal rib 1 is provided between the pair of vertical ribs 1g and 1g and in the space 7 between the pair of central horizontal ribs 1f and 1f.
A partial vertical rib 8 is formed so as to straddle f and 1f, and an erector hole 9 for hoisting by a crane or the like is formed in the partial vertical rib 8. Further, drainage holes 10 are formed at positions in contact with the outer peripheral surface 1c at three positions between the axial end surface 1a and the vertical rib 1g and between the vertical ribs 1g and 1g in each horizontal rib 1f.

-B-Type Segment SB-As shown in FIG. 6, the B-type segment SB is basically A except that one circumferential end face 2b is different as described above.
It is the same as the mold segment SA, and only the differences will be described.
The circumferential end surface 2b for the K-shaped segment is formed as a surface whose inner diameter side is inclined at an inward angle e (11.6 degrees) in the direction toward the adjacent lateral rib 1F side.

In addition, of a large number of space portions s surrounded by the axial end surface 1b and the vertical and horizontal ribs 1g and 1f on the four peripheral surfaces, tunnel rings are provided at two locations at both ends in the axial direction just in the middle in the circumferential direction. After constructing the TR, a thick-walled circle having a large wall thickness in a large circular range so as to compensate for the strength decrease when the injection hole 13 for injecting concrete is formed in the surplus space existing outside the tunnel ring TR. Part 14 [Fig. 6
(See (b)) is formed in advance.

-K type segment SK-The K type segment SK has a basic circumferential angle k of 17.1.
It is extremely short at 43 degrees and has one first bolt hole 4 and two lateral ribs 1F, 1F in the circumferential direction. Both circumferential direction end faces 5a, 5a are formed on a surface inclined by an outward angle g (11.6 degrees) in a direction in which the inner diameter side moves away from the adjacent lateral rib 1F to the opposite side, and the inward angle of the B-shaped segment SB is formed. It is set to cancel e.

[Other Embodiments] << 1 >> The tunnel ring TR shown in FIG. 8 has a larger diameter than that shown in FIG. 1, and a unit tunnel ring tr is formed from seven segments. The segments used for this are four a-type segments Sa (see FIG. 9), 1
B1 type segments Sb1 [see FIG. 11 (a)], 1
One b2-type segment Sb2 [see FIG. 11 (b)] and one k-type segment Sk (see FIG. 12), both of which are composed of a cast iron main frame 16 and a concrete part 15 (described above). The same structure as the conventional example).

The tunnel ring TR has a structure in which the k-type segment Sk is moved in the tunnel axis direction (arrow A direction) and is pushed and set between the b1-type segment Sb1 and the Sb2-type segment Sb2. The segment Sb and the b2-type segment Sb2 are the same except that the inclination directions of the one circumferential end surfaces 17b and 18b are opposite to each other. In the case of these segments, since the concrete portion 15 is on the outer peripheral side, the space between the circumferential end surface 1b and the adjacent horizontal rib 1f has a shape that widens toward the outer diameter side, and the inclination angle for die cutting is Since it has a structure that can be taken sufficiently, it can be molded with a general mold with a two-divided structure, and it is not necessary to use a sand mold.

As shown in FIGS. 9 and 10, the a-type segment Sa has a circumferential angle of 57.6 degrees, and the lateral ribs 1f,
The pitch interval h of 1f is set to 7.2 degrees, and the pitch interval i of the first bolt holes 4 and 4 at four locations on one side is set to 14.4 degrees (= 2h). The circumferential angle w3 between the circumferential end surface 1b and the adjacent lateral rib 1F is 3.6 degrees, and the circumferential angle j between the circumferential end surface 1b and the first bolt hole 4 at the end is 7.2 degrees ( = H) respectively. An erector hole 19 which is a screw hole for detachably mounting a suspender (not shown) is formed at the center of the tunnel axis direction on the normal line Z.

<< 2 >> As shown in FIG. 13, the horizontal rib 1f
In the steel plate welded structure (steel type) segment Ss1 formed by arranging radially, the pitch between the lateral ribs 1f and 1f is P, the interval between the circumferential end surface 1b and the lateral rib 1f is P, and the adjacent first bolts are The pitch between holes 4 and 4 is 3P,
The pitch between the circumferential end face 1b and the end first bolt hole 4 may be set to 1.5P.

<< 3 >> As shown in FIG. 14, the lateral rib 1f
In the steel plate welded structure (steel type) segment Ss2 formed by arranging radially, the pitch between the lateral ribs 1f and 1f is set to P, and the interval between the circumferential end surface 1b and the lateral rib 1f is set to 1 / 2P. 1 bolt hole 4, pitch between 4 is 2
The pitch between the circumferential end face 1b and the first bolt hole 4 at the end may be set to P.

<< 4 >> As shown in FIG. 15, in the cast iron segment Sm, the pitch between the lateral ribs 1f and 1f is P, and the distance between the circumferential end surface 1b and the lateral rib 1f is 1 /.
3P, pitch between adjacent first bolt holes 4 and 4 is 5 / 3P
The pitch between the circumferential end face 1b and the first bolt hole 4 at the end may be set to 5 / 6P.

<< 5 >> As shown in FIG. 16, in the cast iron segment Sn, the pitch between the lateral ribs 1f and 1f is P, and the distance between the circumferential end face 1b and the lateral rib 1f is 2 /.
3P, pitch between adjacent first bolt holes 4 and 4 is 7 / 3P
Further, the pitch between the circumferential end face 1b and the first bolt hole 4 at the end may be set to 7 / 6P.

<< 6 >> In a cast iron segment, the angular position reference Y of the lateral rib 1f may be set at a rib root or a position in the radial direction. In the cast iron segment SA shown in FIG. 2, the lateral rib 1F adjacent to the circumferential end face 1b may be extended to the inner diameter side end as a segment.

[Brief description of drawings]

FIG. 1 is a perspective view showing a tunnel ring.

FIG. 2 shows an A type segment, (a) is a sectional side view,
(B) is a bottom view

FIG. 3 is a sectional view taken along the line of FIG.

FIG. 4 is a cross-sectional view taken along the line II of FIG.

FIG. 5 is a front view showing a circumferential end face of an A-type segment.

FIG. 6 shows a B-shaped segment, (a) is a sectional side view,
(B) is a bottom view

FIG. 7 shows a K-shaped segment, (a) is a sectional side view,
(B) is a bottom view

FIG. 8 is a perspective view showing a tunnel ring having another structure. A bottom view of the B-shaped segment.

FIG. 9 shows an a-type segment, (a) is a sectional side view,
(B) is a bottom view

10 is a cross-sectional view taken along the line HO of FIG.

FIG. 11A is a bottom view of a b1 type segment, and FIG.
Is a bottom view of the b2 segment

FIG. 12 is a bottom view of the k-shaped segment.

FIG. 13 is a side view showing an outline of a segment of a second different structure.

FIG. 14 is a side view showing the outline of a segment of a third different structure.

FIG. 15 is a side view showing an outline of a segment of a fourth different structure.

FIG. 16 is a side view showing the outline of a segment of a fifth alternative structure.

FIG. 17 is a side view showing a situation when earth pressure acts on a connecting portion of a segment.

FIG. 18 shows a conventional segment, (a) is a sectional side view, and (b) is a bottom view.

FIG. 19 is a sectional side view showing a segment when the bolt holes are simply halved.

[Explanation of symbols]

1a Tunnel axial end face 1b First and second connection end faces 1f rib part 1F Rib section at the end of the tunnel R connection w1 first interval w2 second interval

Claims (2)

[Claims] 1. A tunnel segment for forming an inner wall of a tunnel by arranging a plurality of them in the circumferential direction of the tunnel and in the axial direction of the tunnel and connecting them to each other, the segments being adjacent to each other in the axial direction of the tunnel axial direction. The connecting portions for connecting the segments are provided at equal intervals in the tunnel circumferential direction on the end face in the tunnel axial direction, and the connecting portion located at one end in the tunnel circumferential direction of these connecting portions and the first portion at the one end in the tunnel circumferential direction are provided. The distance between the first connecting end surface and the distance between the connecting portion located at the other end in the tunnel circumferential direction of the connecting portion and the second connecting end surface at the other end in the tunnel circumferential direction are both adjacent to each other. A rib portion extending in the tunnel axial direction while being set to a value equal to or approximately equal to half the distance and extending between the pair of tunnel axial end faces in the tunnel circumferential direction, etc. A rib portion that is provided at every interval and that is located at one end of the rib portion in the tunnel circumferential direction and a first gap between the first connection end face and the rib portion that is located at the other end of the rib portion in the tunnel circumferential direction. And a second distance between the second connection end face and the second distance between the adjacent rib portions are set equal to each other at a distance equal to or less than the distance between the adjacent rib portions, and the distance between the adjacent rib portions is smaller than the distance between the adjacent coupling portions. A tunnel segment set to small. 2. The first spacing and the second spacing are set to a value which is half or almost half the spacing between the adjacent rib portions, and the spacing between the connecting portions is set between the rib portions. The tunnel segment according to claim 1, wherein the segment is set to a value twice the interval.