JP6967978B2 - Sewer tunnel and its construction method - Google Patents

Description

The present invention relates to a sewer tunnel having a substantially egg-shaped or substantially oval-shaped tunnel cross section and a construction method thereof.

Conventionally, a sewerage tunnel constructed by assembling bricks into an egg-shaped cross section has been known for a long time. The sewer tunnel with an egg-shaped cross section is vertical and is constructed narrower than the tunnel with a substantially circular cross section. It is known that the internal space is formed so that the cross-sectional area of the lower part is smaller than that of the upper part, so that the water flow can be secured even when there is little sewage or sewage.
On the other hand, in recent diversion type sewers, sewage pipes and rainwater pipes are made in separate pipelines with circular cross sections. Further, in the combined sewerage system, one pipeline having a circular cross section is laid, and rainwater and sewage are combined and drained.

Further, for example, Patent Document 1 discloses a tunnel having a substantially oval shape as a cross-sectional shape. This tunnel is a road tunnel, and the upper space and the lower space of the tunnel having a substantially oval cross section are separated by a middle floor slab provided in the horizontal direction. This tunnel can be constructed under an existing road with a limited width, and a primary reinforcement layer is constructed at the top to prevent the ground from collapsing during excavation. By completing the construction of the upper space in the lower part of the primary reinforcement layer in advance of the entire section, then constructing a plate-shaped middle floor slab under the upper space, and further forming the lower space under it, many We are building a floor tunnel. Moreover, flat invert concrete is poured in the lower part of the lower space.

Japanese Unexamined Patent Publication No. 11-62464

However, in the tunnel described in Patent Document 1, the middle floor slab that separates the upper space and the lower space and the invert concrete at the bottom of the lower space are flat, so when used as a sewer tunnel, the upper space and the lower space can be used. There was a problem that if the amount of flowing sewage or sewage was small, it would not flow sufficiently. Therefore, there is a possibility that it will be contaminated with sewage or the like.
Moreover, since it is a construction method in which the primary reinforcing layer, the upper space, the middle floor slab, and the lower space are sequentially constructed downward in the ground from the upper side, there is a problem that the construction period is long and the cost is high.

The present invention has been made in view of such a problem, and is a sewerage tunnel capable of forming a water flow even if the amount of sewage or sewage in the upper space or the lower space is small, and can be constructed in a short period of time. And the purpose is to provide the construction method thereof.

The sewer tunnel according to the present invention is provided with a segment ring having a substantially oval or oval cross section and an inner lid partition portion that divides the segment ring into two stages, an upper space and a lower space, and the inner lid partition portion is on the lower space side. It is characterized in that it is formed in a substantially concave curved cross section having a convex shape.
According to the present invention, the sewerage tunnel can be separated into an upper space and a lower space by an inner lid partition to allow different types of sewage such as rainwater and sewage to flow separately, and the inner lid partition which is the bottom of the upper space. Since the portion is formed in a concave curved shape in cross section and the bottom of the lower space is also oval or oval, it can be collected at the bottom and flowed smoothly even if the amount of water is small.

Further, the upper space of the segment ring is partitioned into a substantially circular cross section including the upper first arc portion and the inner lid partition portion, and the lower space of the segment ring has a smaller diameter than the inner lid partition portion and the first arc portion. It is preferable that the lower portion is partitioned by a substantially second arc portion, both side ends of the first arc portion, and a connecting portion connecting both side ends of the second arc portion.
As a result, even if the amount of water is small, rainwater, sewage, etc. can be collected at the inner lid partition of the upper space and the second arc of the lower space and flowed individually and smoothly, and the subsequent treatment is easy and the treatment cost. Can be reduced.

Further, in the upper space, it is preferable that the inner lid partition portion is detachably installed.
Workers can walk on the inner lid partition in the upper space for maintenance and inspection, and by removing the inner lid partition, maintenance and inspection of the lower space can be performed quickly. In addition, by removing the inner lid partition portion, sewage in the upper space can be allowed to flow into the lower space to clean sewage and the like.

Further, it is preferable to include a locking member provided in the inner lid partition portion and a cord-shaped member for opening the inner lid partition portion via the locking member.
Since the inner lid partition can be opened or removed via the locking member by pulling the cord-shaped member, rainwater in the upper space can be flowed into the lower space to clean the sewage, and the lower passage can be inspected from the upper passage. It is easy to do.

The method for constructing a sewer tunnel according to the present invention is a process of rotationally excavating the ground with a first cutter head equipped with a relatively large-diameter cutter bit and constructing a first arc portion in which segments are assembled behind the ground. , The ground was rotationally excavated with a second cutter head equipped with a relatively small diameter cutter bit, which was partially overlapped in the radial direction under the first cutter head, and a segment was assembled behind it. The ground between the process of constructing the second arc portion at the bottom and the arc portion or tangential portion connecting the intersection of the first cutter head and the second cutter head with both ends of the first arc portion and the second arc portion. The process of excavating with a sub-cutter and constructing a connecting part with a segment assembled behind it is performed at the same time to connect the first arc part, the second arc part and the connecting part, and the cross section concave to form a convex downward. It is characterized in that a segment ring having a substantially oval cross section is constructed by partitioning the upper space and the lower space by a curved inner lid partition portion.
According to the present invention, a segment ring having a substantially oval cross section can be formed by simultaneously constructing a first arc portion in the upper space, a second arc portion in the lower space, and a connecting portion connecting the two. The construction period is short and the construction cost is low.

According to the sewerage tunnel and its construction method according to the present invention, a substantially concave curved inner lid partition portion having a substantially concave cross section is constructed between the upper space and the lower space of the sewerage tunnel having a substantially oval or oval cross section. Therefore, even if the amount of water in the upper space and the lower space is small, it can be collected at the bottom to secure the water flow.

It is a vertical sectional view of the sewer tunnel by the 1st Embodiment of this invention. It is a vertical cross-sectional view which shows the sewage and sewage flowing through the sewer tunnel shown in FIG. FIG. 3 is a cross-sectional view of a shield excavator showing a method of constructing a sewer tunnel for excavating the sewer tunnel shown in FIG. It is a front view of the cutter head in the shield excavator shown in FIG. It is a vertical sectional view of the sewer tunnel by the 2nd Embodiment of this invention. It is a figure which shows the eyebolt connected to the inner lid partition part shown in FIG.

Hereinafter, the sewerage tunnel according to each embodiment of the present invention and its construction method will be described with reference to FIGS. 1 to 6.
1 to 4 are views showing the sewerage tunnel 1 and its construction method according to the first embodiment.
The sewerage tunnel 1 according to the present embodiment shown in FIG. 1 is constructed in the ground by, for example, a shield excavator, and is installed on the lower side of a road having a limited width. The sewer tunnel 1 has a cross-sectional shape of an egg-shaped segment ring 1a vertically arranged so that the upper portion has a large diameter and the lower portion has a small diameter.

In the oval segment ring 1a which is a vertical cross section of the sewer tunnel 1, a large diameter arc portion formed in an arc shape by connecting the large diameter segments 2 with a joint so as to form a part of a relatively large diameter circle R1 on the upper side. 3 has a small diameter arc portion 5 formed in an arc shape by connecting small diameter segments 4 with a joint so as to form a part of a circle R2 having a relatively small diameter on the lower side. The large-diameter arc portion 3 has the center point O1 of the circle R1 and is formed in a substantially semicircular shape, for example, and the small-diameter arc portion 5 has the center point of the circle R2 and is formed in an arc shape smaller than the semicircle. ing.
Both ends of the large-diameter arc portion 3 and both ends of the small-diameter arc portion 5 have a connecting arc portion 7 formed in an arc shape by connecting the middle segment 6 with a joint. The connecting arc portion 7 forms a part of a circle R3 having a diameter larger than the diameter of the large diameter segment 2 of the large diameter arc portion 3 by the middle segment 6.

The center point O3 of the circle R3 provided on the outside of the sewer tunnel 1, the virtual line L1 connecting the center point O1 of the large-diameter arc portion 3 and the end of the large-diameter arc portion 3, and the center of the center point O3 and the small-diameter arc portion 5. The lengths of the virtual line L2 connecting the point O2 and the end of the small-diameter arc portion 5 are substantially the same. The connecting arcs 7 form arcs connecting the ends of the large-diameter arcs 3 and the small-diameter arcs 5 around the center point O3 in the angular range between the virtual lines L1 and L2 on both sides of the sewer tunnel 1. Is forming.
As a result, each of the arc-shaped large-diameter arc portions 3, the small-diameter arc portions 5, and the connecting arc portions 7 formed by the plurality of segments 2, 4, and 6 has an egg-shaped segment having a substantially egg-shaped outer shell cross-sectional shape. It forms a ring 1a.

The inner surface of the upper middle segment 6 (hereinafter referred to as reference numeral 6A) connected to the end of the large-diameter arc portion 3 in the connecting arc portions 7 on both sides is abbreviated as the inner peripheral surface of the large-diameter arc portion 3. Forming the same or smaller radius of curvature. Moreover, a stepped receiving portion 6b is formed on the inner surface of the middle stage segments 6A on both sides, and an inner lid partition portion 10 connecting the inner lid segments 10a is detachably fitted between the stepped receiving portions 6b on both sides. ..

The inner lid partition portion 10 has a radius substantially the same as or slightly smaller than that of the large-diameter segment 2, and forms a concave curved cross section that is convex toward the small-diameter arc portion 5 at the lower portion. Therefore, the large-diameter arc portion 3, the middle segment 6A, and the inner lid partition portion 10 form a circular space having substantially the same cross section as the large-diameter circle R1, and is an upper space for flowing sewage such as rainwater. It constitutes 12 (upper pipeline). In the upper space 12 of the sewerage tunnel 1 shown in FIG. 2, even when the amount of sewage such as rainwater is small, it can be collected at the bottom of the inner lid partition portion 10 having an arcuate cross section and smoothly flowed.

Further, in the sewerage tunnel 1, the space below the upper space 12 is composed of a small-diameter arc portion 5, connecting arc portions 7 on both sides thereof, and an inner lid partition portion 10 fitted to a stepped receiving portion 6b of the middle stage segment 6A. It constitutes a partitioned lower space 13 (lower pipeline).
The lower space 13 is, for example, a flow path through which sewage or the like flows, and since the lower part thereof is formed to be narrower than the upper space 12 by a small diameter arc portion 5, even if the amount of water is small, it can be collected at the bottom and flowed smoothly. can. Sewage may be flowed in the upper space 12 and rainwater or the like may be flowed in the lower space 13.

Therefore, the sewerage tunnel 1 according to the present embodiment is provided with a circular tube having the same cross-sectional area as a whole in order to form an egg-shaped segment ring 1a having a vertically long egg-shaped cross section that tapers from the upper part to the lower part in the vertical cross section. Compared to the case where the width is relatively narrow, it can be laid under the narrow road. Moreover, since the width narrows from the upper space 12 to the lower space 13, the water depth and the flow velocity can be increased even in a low slope area where the flow rate is small and it is difficult to secure the minimum flow velocity, and the flowing sewage can be dealt with. Stable sweepability can be ensured.

Next, the construction method of the sewerage tunnel 1 according to the first embodiment of the present invention will be described with reference to FIGS. 3 and 4.
The shield excavator 11 for excavating the sewer tunnel 1 according to the present embodiment has an integrated configuration in which the master unit 14 and the slave unit 15 are combined. As shown in FIGS. 3 and 4, the master unit 14 has a large-diameter disk-shaped main cutter head 16 (first cutter head) digging a ground in front of the master unit 14 so as to be rotatable and excavated. A disk-shaped sub-cutter head 24 that digs the ground is installed on the front surface so that it can be rotary excavated. The sub-cutter head 24 is arranged so as to overlap the main cutter head 16 on the back surface side of the main cutter head 16 so as not to interfere with the rotation shaft 16a forming the center of rotation thereof.

In the master unit 14, a cutter bit 17 for rotary excavation of the ground is mounted on the front surface of the main cutter head 16, for example, at a substantially X-shaped base. The main cutter head 16 excavates and forms an upper space 12 provided with a large-diameter arc portion 3. On the back side of the main cutter head 16, an erector device 19 is installed as a segment assembly device for assembling the large-diameter segment 2 along the tubular inner peripheral surface of the shield frame 18. The tunnel hole is formed by a shield method in which the ground is dug by the rotation of the main cutter head 16. The large-diameter segment 2 having a substantially arc plate shape is assembled to the front surface of the existing segment with a joint before and after the tunnel excavation direction to construct the large-diameter arc portion 3.
The shield excavator 11 is provided with a jack 21A that presses the large-diameter segment 2 assembled by the erector device 19 from the front to the rear to take a reaction force. The upper space 12 provided with the large-diameter arc portion 3 is formed by the Elector device 19.

Further, in the slave unit 15, the sub-cutter head 24 (second cutter head) is set so as to be rotatable and excavable in order to dig a ground in the front on the back side of the main cutter head 16. On the front surface of the sub-cutter head 24, a cutter bit 25 for rotary excavation of the ground is attached to, for example, a substantially X-shaped base. On the back side of the sub-cutter head 24, the small diameter segment 4 can be assembled along the tubular inner peripheral surface of the shield frame 28 by the Elector device 19.
The tunnel hole is formed by a shield method in which the ground is dug by the rotation of the sub-cutter head 24. By the Elector device 19, the substantially arc plate-shaped small diameter segment 4 is assembled to the front surface of the existing segment with a joint before and after the tunnel excavation direction to construct the small diameter arc portion 5.

The slave unit 15 of the shield excavator 11 is provided with a jack 21B for pressing the small diameter segment 4 assembled by the erector device 19 from the front to the rear. The Elector device 19 forms a lower space 13 provided with a small-diameter arc portion 5.

The upper part and the lower part of the egg-shaped segment ring 1a can be constructed by partially overlapping the rotation locus of the main cutter head 16 on the back side of the main cutter head 16. At that time, the degree of overlap is adjusted so that the sub-cutter head 24 does not interfere with the rotation shaft 16a of the main cutter head 16.
Further, as shown in FIG. 4, between the intersection P of the large-diameter circle R1 that draws the rotation locus of the main cutter head 16 and the small-diameter circle R2 that draws the rotation locus of the sub-cutter head 24 and the connecting arc portion 7. A main sub-cutter 30 and a sub-sub-cutter 31 are used to excavate a space.
The main sub-cutter 30 is connected to a hydraulic jack 33 that extends radially outward from the rotation shaft 16a of the main cutter head 16 or an appropriate position in the radial direction and is expandable and contractible. The main sub-cutter 30 is capable of partially excavating a lower region that is separated from the main cutter head 16 in a region along the outer shape of the connecting arc portion 7 while extending the hydraulic jack 33.

Similarly, the sub-sub-cutter 31 is connected to a hydraulic jack 34 that extends radially outward from the rotation shaft 24a of the sub-cutter head 24 or an appropriate position in the radial direction and is expandable and contractible. The sub-sub-cutter 31 is capable of excavating an upper region away from the sub-cutter head 24 in a region along the outer shape of the connecting arc portion 7 while extending the hydraulic jack 34. The portion of the egg-shaped segment ring 1a that cannot be excavated by the main cutter head 16 and the sub-cutter head 24 is excavated by projecting an appropriate amount by computer-controlling the main sub-cutter 30 and the sub-sub-cutter 31.
In the region excavated by the main sub-cutter 30 and the sub-sub-cutter 31 in this way, the substantially arc plate-shaped middle-stage segments 6A and 6 are assembled to the front surface of the existing segment with joints before and after the tunnel excavation direction to construct the connecting arc portion 7. .. The connecting arc portion 7 is formed in an arc shape by connecting the ends of the large diameter arc portion 3 and the small diameter arc portion 5 to each other.

The inner lid partition portion 10 may be constructed by the elector device 19 at the same time as the construction of the egg-shaped segment ring 1a composed of the large-diameter arc portion 3, the small-diameter arc portion 5, and the connecting arc portion 7 at the time of construction of the sewer tunnel 1. can. In this case, since the inner lid partition portion 10 is installed by partitioning the inside of the egg-shaped segment ring 1a into the upper space 12 and the lower space 13 at an intermediate height, it is not affected by earth pressure.

The sewerage tunnel 1 according to the present embodiment has the above-mentioned configuration, and then a method of using the sewerage tunnel 1 will be described.
When using the sewer tunnel 1, rainwater or the like flows down into the upper space 12 of the egg-shaped segment ring 1a through a drainage port, a manhole, etc. .. Even if the amount of water such as rainwater is small, it can be collected at the bottom of the concave curved surface of the inner lid partition portion 10 to form a water flow.
On the other hand, the sewage is discharged to the lower space 13 of the egg-shaped segment ring 1a through a drainage pipe such as a flush toilet or a septic tank. At that time, since the bottom portion of the lower space 13 is formed by a circle R1 having a width narrower than that of the upper space 12 and a circle R2 having a smaller diameter than the inner lid partition portion 10 by the small diameter arc portion 5, even if the amount of sewage is small. It can be collected at the bottom to form a water flow and flow smoothly.

Further, when a worker who performs maintenance and management inspects while walking in the upper space 12 of the sewerage tunnel 1, he / she can walk in the area of the middle stage segment 6A or the inner lid partition portion 10. Therefore, it is possible to walk without getting the shoes wet, the walking speed is increased, and maintenance and inspection can be performed efficiently.
By opening the inner lid partition 10 and allowing a part of the increased water flow in the upper space 12 to flow to the lower space 13 in rainy weather or the like, the sewage in the lower space 13 used as a sewage pipe can be flowed and cleaned. .. Further, when there is a possibility that the water level of the upper space 12 rises sharply due to heavy rain or the like, it is possible to prevent rainwater from overflowing from the manhole or the like by removing the inner lid partition portion 10 in advance and flowing it into the lower space 13.

As described above, according to the sewerage tunnel 1 and its construction method according to the present embodiment, since the vertical cross-sectional shape is formed into a vertically long egg-shaped segment ring 1a whose diameter is reduced from the upper side to the lower side, a road having a narrow width or the like is formed. It can be laid at the bottom of the tunnel and can be used effectively.
Since the upper space 12 of the egg-shaped segment ring 1a is formed by the inner lid partition portion 10 and the lower space 13 is formed by the small diameter arc portion 5, the bottom space is collected at the bottom even if the amount of rainwater or sewage is small to secure the water flow. Can be transferred and processed. By removing the inner lid partition portion 10 and flowing the increased rainwater to the lower space 13 in rainy weather or the like, the lower space 13 can be cleaned and the rainwater can be prevented from overflowing from the upper space 12 onto the road.

In particular, since the small-diameter arc portion 5 of the lower space 13 has a smaller diameter than the inner lid partition portion 10 of the upper space 12, the water depth can be obtained and the flow velocity can be increased even in a low-gradient area where the flow rate is small and it is difficult to secure the minimum flow velocity. It can be accelerated and stable sweeping property can be ensured.
Further, in the sewerage tunnel 1 composed of the egg-shaped segment ring 1a, the inner lid partition portion 10 separates the upper space (upper pipeline) 12 through which rainwater or the like flows and the lower space (lower pipeline) 13 through which sewage or the like flows. It is possible to reduce the cost of treating rainwater and sewage at water treatment plants.
Further, since the upper space 12 and the lower space 13 of the sewerage tunnel 1 can be constructed at the same time, the construction cost is low. Moreover, since the worker can walk on the inner lid partition portion 10 during maintenance and inspection, the inspection can be performed efficiently without getting the shoes wet.

Although the sewerage tunnel 1 and the construction method thereof according to the embodiment of the present invention have been described in detail above, the present invention is not limited to the above-described embodiment and may be appropriately modified without departing from the spirit of the present invention. Substitutions and the like are possible, all of which are included in the present invention. Hereinafter, other embodiments and modifications of the present invention will be described, but the same reference numerals will be used for the same or similar parts and members as in the above-described embodiments, and the description thereof will be omitted.

Next, the sewerage tunnel 40 according to the second embodiment of the present invention will be described with reference to FIGS. 5 and 6.
The sewerage tunnel 40 according to the second embodiment has the same configuration as the sewerage tunnel 1 according to the first embodiment. In the present embodiment, the insert bolt 41a is screwed and fixed to the inner ceiling of the upper space 12 in the egg-shaped segment ring 1a. Similarly, insert bolts 41b were screwed and fixed to both ends of the inner lid partition portion 10 fitted to the stepped receiving portions 6b of the middle stage segments 6A on both sides of the upper space 12. Moreover, the eye bolt 43 is screwed and fixed to the insert bolt 41a on the inner ceiling of the upper space 12. Fixing bolts 42 are tightened to the inner lid partition 10 and the middle segment 6A to the insert bolts 41b at both ends of the inner lid partition 10, and the inner lid partition 10 is fixed.

When a worker inspects the sewer tunnel 40, the worker in the upper space 12 inspects the upper space 12 and the lower space 13. At that time, the worker who inspected the upper space 12 removes the fixing bolts 42 from the insert bolts 41b at both ends of the inner lid partition portion 10 and tightens the eye bolts 43 respectively. Then, a chain 45 is passed through the eyebolt 43 on the inner surface of the ceiling as a cord-like member, and both ends are locked to the eyebolts 43 at both ends of the inner lid partition portion 10. A hook bolt may be attached instead of the eye bolt 43, and these are included in the locking member. A chain block 46 is attached to the chain 45 at appropriate locations.
Then, when the worker pulls up the chain 45 with the chain block 46, the inner lid partition portion 10 is pulled up via the eyebolt 43, so that the inside of the lower space 13 can be inspected.

In each of the above-described embodiments, the egg-shaped segment ring 1a is used as the sewerage tunnels 1 and 40, but the present invention is not limited to such a configuration. For example, a segment ring having an oval cross section extending in the vertical direction may be used, and the inner lid partition portion 10 for partitioning the inside thereof may be fitted and fixed, or may be detachably installed.
Further, in each of the above-described embodiments, both ends of the large-diameter arc portion 3 and the small-diameter arc portion 5 of the oval segment ring 1a are formed by a substantially arc-shaped connecting arc portion 7, but the large diameter is replaced with the connecting arc portion 7. The tangential portions at both ends of the arc portion 3 and the small diameter arc portion 5 may be formed in a linear cross section, and these are included in the connecting portion.

In each of the above-described embodiments, the inner lid partition portion 10 is formed in an arc shape having a larger diameter than the small diameter arc portion 5, but may be formed so as to have an inner diameter equal to or smaller than that of the small diameter arc portion 5. .. Further, although the inner lid partition portion 10 is formed by connecting a plurality of inner lid segments 10a, it may be formed by an integral substantially arc plate in the width direction.
The large-diameter arc portion 3 is included in the first arc portion, the small-diameter arc portion 5 is included in the second arc portion, and the connecting arc portion 7 is included in the connecting portion.

1, 40 Sewer tunnel 1a Oval segment ring 2 Large diameter segment 3 Large diameter arc part 4 Small diameter segment 5 Small diameter arc part 6, 6A Middle stage segment 6b Stepped receiving part 7 Connecting arc part 10 Inner lid partition 11 Shield excavator 12 Upper space (upper pipeline)
13 Lower space (lower pipeline)
16 Main cutter head 16a, 24a Rotating shaft 15B Second Elector device 16 Main cutter head 17, 25 Cutter bit 24 Sub-cutter head 30 Main sub-cutter 31 Sub-sub-cutter 33, 34 Hydraulic jack 41a, 41b Insert bolt 43 Eye bolt 45 Chain 46 Chain block

Claims (5)

With an egg-shaped or oval-shaped segment ring in cross section,
The segment ring is provided with an inner lid partition portion that divides the segment ring into two stages, an upper space and a lower space.
The sewer tunnel is characterized in that the inner lid partition portion is formed so as to be curved so as to form a convex on the lower space side. The upper space of the segment ring is partitioned into a substantially circular cross section including the upper first arc portion and the inner lid partition portion.
The lower space of the segment ring includes the inner lid partition portion, the lower second arc portion having a diameter smaller than that of the first arc portion, both end portions of the first arc portion, and both side ends of the second arc portion. The sewerage tunnel according to claim 1, which is partitioned by a connecting portion connecting the portions. The sewerage tunnel according to claim 2, wherein the inner lid partition portion is detachably installed in the upper space. The invention according to any one of claims 1 to 3, further comprising a locking member provided on the inner lid partition portion and a cord-shaped member for opening the inner lid partition portion via the locking member. Sewer tunnel. The process of rotating and excavating the ground with the first cutter head equipped with a relatively large diameter cutter bit, and constructing the first arc part with the segment assembled behind it at the top.
The ground was rotationally excavated with a second cutter head equipped with a cutter bit having a relatively small diameter, which was partially overlapped in the radial direction under the first cutter head, and a segment was assembled behind the ground. The process of constructing the second arc part at the bottom and
The ground between the intersection of the first cutter head and the second cutter head and the arc portion or the tangential portion connecting both ends of the first arc portion and the second arc portion is excavated by a sub-cutter, and a segment is formed behind the arc portion. At the same time, the process of constructing the connected part that was assembled
By connecting the first arc portion, the second arc portion, and the connecting portion, and partitioning the upper space and the lower space by an inner lid partition portion having a concave curved cross section that is convex downward, the cross section is substantially oval. A method of constructing a sewer tunnel, which is characterized by constructing a segment ring.

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