JP2019127683A - Sewerage tunnel and construction method for the same - Google Patents

Abstract

To form a water stream even with a small amount of sewage in an upper space or a lower space.SOLUTION: A sewerage tunnel 1 comprises an egg-shaped segment ring 1a, and an inner lid partition part 10 partitioning the egg-shaped segment ring 1a into two stages of an upper space 12 and a lower space 13. The inner lid partition part 10 is formed into a roughly concave face convexed to the lower space 13 side. A large diameter circular arc part 3 formed of a large diameter segment 2 and the inner lid partition part 10 form the roughly circular upper space 12. A roughly circular arc shape of the inner lid partition part 10 can collect even a small amount of rainwater at the bottom thereof and accelerate the flow speed. The inner lid partition part 10, a small diameter circular arc part 5 and a connected circular arc part 7 connecting both ends of the large diameter circular arc part 3 and the small diameter circular arc part 5 form the lower space 13. The diameter of the small diameter circular arc part 5 is smaller than that of the inner lid partition part 10, therefore, a water stream can be formed with a small amount of water.SELECTED DRAWING: Figure 1

Description

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

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

  For example, Patent Document 1 discloses a substantially elliptical cross-sectional shape of the tunnel. 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 mid floor slab provided in the horizontal direction. This tunnel can be constructed under an existing road with a limited width, and by installing a primary reinforcement layer on the top, it prevents the ground from collapsing during excavation. In the lower part of the primary reinforcement layer, the construction of the upper space is completed in advance for all sections, and then a plate-like mid-floor version is constructed below the upper space, and the lower space is formed further below. We are building a multistory tunnel. Moreover, flat invert concrete is placed in the lower part of the lower space.

Japanese Patent Application Laid-Open No. 11-62464

However, in the tunnel described in Patent Document 1, the middle floor slab that divides 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 are There is a problem that if the amount of flowing sewage or sewage is small, it does not flow sufficiently. Therefore, there was a possibility that it might be polluted with sewage etc.
Moreover, since the construction method is such that the primary reinforcing layer, the upper space, the middle floor slab, and the lower space are sequentially constructed downward from the upper side in the ground, 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 problems, and can form a water flow even when the amount of sewage or sewage in the upper space or lower space is small, and can be constructed in a short period of time. And it aims at providing the construction method.

A sewer tunnel according to the present invention includes a segment ring having a substantially oval cross section or an oval cross section, and an inner lid partition portion that partitions the segment ring into two stages of 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 the shape of a substantially concave surface having a convex cross section.
According to the present invention, the sewer tunnel is separated into the upper space and the lower space by the inner lid partition portion, and different types of sewage such as rain water and sewage can be separately flowed, and the inner lid partition which is the bottom portion of the upper space Since the section is formed in the shape of a concave curved surface, and the bottom of the lower space is also oval or oval, even if the amount of water is small, it can be collected at the bottom and flowed smoothly.

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 substantially arcuate part is partitioned by a connecting part that connects both end parts of the first arc part and both end parts of the second arc part.
This makes it possible to collect rainwater, sewage, etc. at the upper lid's inner lid partition and the second arc in the lower space individually and smoothly even if the amount of water is small, making subsequent processing easy and processing cost Can be reduced.

In addition, in the upper space, it is preferable that the inner lid partition part be installed in a removable manner.
Maintenance and inspection can be performed by an operator walking on the inner lid partition portion in the upper space and the lower space can be quickly maintained and inspected by removing the inner lid partition portion. Further, by removing the inner lid partition part, the sewage of the upper space can be flowed into the lower space to clean the sewage and the like.

Moreover, it is preferable to provide the latching member provided in the inner lid partition part, and the cord-like member which opens an inner lid partition part via a latching member.
By pulling the cord-like member, the inner lid partition can be opened or removed via the locking member, allowing rainwater etc. in the upper space to flow into the lower space to clean up the sewage, etc., and inspecting the lower passage from the upper passage Easy to do.

The construction method of the sewer tunnel according to the present invention includes a step of rotating and excavating the ground with a first cutter head having a relatively large diameter cutter bit, and constructing a first arc portion having a segment assembled at the rear thereof at the upper part, Rotating and excavating the ground with the second cutter head, which is arranged to be partially overlapped in the radial direction below the first cutter head and provided with a relatively small diameter cutter bit, and assembled a segment behind it The step of constructing the second arc portion at the bottom, and the ground between the intersecting portion of the first cutter head and the second cutter head and the arc portion or the tangent portion connecting both ends of the first arc portion and the second arc portion Excavating with a sub-cutter and constructing a connecting part in which segments are assembled behind the sub-cutter, and simultaneously connecting the first arc part, the second arc part and the connecting part; The lid partition portion in the cross section concavely curved to form a convex By partitioning the upper space and a lower space, characterized in that to build a substantially oval segment ring.
According to the present invention, it is possible to form a segment ring having a substantially egg-shaped cross section by simultaneously constructing the first arc portion of the upper space and the second arc portion of the lower space and the connecting portion that connects the two. The construction period is short and the construction cost is low.

  According to the sewer tunnel and the construction method thereof according to the present invention, the inner lid partition part having a substantially concave curved cross section that protrudes downward is formed between the upper space and the lower space of the sewer tunnel having a substantially oval or oval cross section. Therefore, even if the amount of water is small in the upper space and the lower space, the water flow can be secured by collecting at the bottom.

It is a longitudinal cross-sectional view of the sewer tunnel by 1st embodiment of this invention. It is a longitudinal cross-sectional view which shows the sewage and sewage which flow through the sewer tunnel shown in FIG. It is sectional drawing of the shield excavator which shows the sewer tunnel construction method which excavates 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 longitudinal cross-sectional view of the sewer tunnel by 2nd embodiment of this invention. It is a figure which shows the eyebolt connected with the inner cover partition part shown in FIG.

Hereinafter, the sewer tunnel and its construction method according to each embodiment of the present invention will be described with reference to FIGS.
1-4 is a figure which shows the sewer tunnel 1 by 1st embodiment, and its construction method.
A sewer tunnel 1 according to this 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 oval segment ring 1a which is vertically disposed so that the upper portion has a large diameter and the lower portion has a small diameter.

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

An imaginary line L1 connecting the center point O3 of the circle R3 provided outside the sewer tunnel 1, the center point O1 of the large-diameter arc portion 3 and the end of the large-diameter arc portion 3, the center point O3 and the center of the small-diameter arc portion 5 The lengths of the point O2 and the imaginary line L2 connecting the ends of the small-diameter arc portion 5 are substantially the same. The connecting arc part 7 is an arc connecting the ends of the large-diameter arc part 3 and the small-diameter arc part 5 around the center point O3 in the angle range between the virtual lines L1 and L2 on both sides of the sewer tunnel 1. Forming.
As a result, each of the arc-shaped large-diameter arc portion 3, the small-diameter arc portion 5, and the connecting arc portion 7 formed by the plurality of segments 2, 4, 6 has an egg-shaped outer shell cross-sectional shape. A ring 1a is formed.

  The upper middle step segment 6 (hereinafter referred to as 6A) connected to the end of the large diameter arc portion 3 in the connection arc portion 7 on both sides has an inner surface substantially similar to the inner peripheral surface of the large diameter arc portion 3 It forms the same or smaller radius of curvature. Moreover, the stepped receiving portion 6b is formed on the inner surface of the middle step segment 6A on both sides, and the inner lid partition portion 10 connecting the inner lid segment 10a is detachably fitted between the stepped receiving portions 6b on both sides. .

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

In the sewer tunnel 1, the space below the upper space 12 is a small-diameter arc portion 5, a connecting arc portion 7 on both sides thereof, and an inner lid partition portion 10 fitted to the stepped receiving portion 6 b of the middle segment 6 </ b> A. The lower space 13 (lower pipeline) partitioned is constituted.
The lower space 13 is, for example, a flow path for flowing sewage and the like, and the lower part is formed with a small-diameter arc portion 5 narrower than the upper space 12, so that even if the amount of water is small, it can be collected and flowed smoothly at the bottom. it can. In addition, you may pour dirty water to the upper space 12, and may pour rain water etc. to the lower space 13. As shown in FIG.

  Therefore, the sewer tunnel 1 according to the present embodiment is provided with a circular pipe having the same cross-sectional area as a whole in order to constitute an oval segment ring 1a having a longitudinally elongated oval cross-section that tapers from the top to the bottom in the vertical cross section Compared to the case, it can be laid on the lower side of a relatively narrow road. In addition, 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 gradient land where it is difficult to secure a minimum flow velocity with a small flow rate. As a result, stable sweeping performance can be secured.

Next, the construction method of the sewer tunnel 1 by 1st embodiment of this invention is demonstrated with FIG.3 and FIG.4.
The shield excavator 11 for excavating the sewer tunnel 1 according to the present embodiment has an integrated configuration in which a master unit 14 and a slave unit 15 are combined. As shown in FIGS. 3 and 4, the main unit 14 has a large-diameter disk-shaped main cutter head 16 (first cutter head) that digs a natural ground in the front surface and is installed so as to be capable of rotating excavation. A disc-shaped sub cutter head 24 that digs a natural ground in the front is installed so as to be capable of rotating excavation. The sub cutter head 24 is disposed on the back side of the main cutter head 16 so as to overlap the main cutter head 16 in a range that does not interfere with the rotation shaft 16a that forms the center of rotation.

In the main unit 14, a cutter bit 17 for rotating and excavating natural ground is attached to the front surface of the main cutter head 16 at, for example, a substantially X-shaped base. The main cutter head 16 excavates and forms the upper space 12 provided with the large-diameter arc portion 3. An erector device 19 is installed on the back side of the main cutter head 16 as a segment assembling device for assembling the large-diameter segment 2 along the cylindrical inner peripheral surface of the shield frame 18. The tunnel hole is formed by a shield method that digs a natural ground by the rotation of the main cutter head 16. The large-diameter segment 2 having a substantially circular arc plate shape is assembled to the front surface of the existing segment with joints before and after the tunnel digging direction to construct the large-diameter arc portion 3.
The shield excavator 11 is provided with a jack 21A that takes a reaction force by pressing the large-diameter segment 2 assembled by the erector device 19 from the front to the rear. The upper space 12 provided with the large diameter circular arc portion 3 is formed by the elector device 19.

Moreover, in the subunit | mobile_unit 15, the sub cutter head 24 (2nd cutter head) is set so that rotation excavation is possible in order to dig a natural ground to the front at the back side of the main cutter head 16. FIG. A cutter bit 25 for rotating and excavating natural ground is attached to the front surface of the sub cutter head 24, for example, at a base portion having an approximately X shape. On the back side of the sub cutter head 24, the small diameter segment 4 can be assembled along the cylindrical inner peripheral surface of the shield frame 28 by the erector device 19.
The tunnel hole is formed by a shield method in which a natural ground is dug by the rotation of the sub cutter head 24. By means of the erector 19, the substantially arcuate plate-shaped small-diameter segment 4 is assembled on the front surface of the existing segment with a joint before and after the tunneling direction to construct the small-diameter arc portion 5.

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

The upper and lower parts of the egg-shaped segment ring 1a can be constructed by the sub cutter head 24 partially overlapping the rotation trajectory of the main cutter head 16 on the back side of the main cutter head 16. At this time, the degree of overlapping is adjusted to such an extent that the secondary cutter head 24 does not interfere with the rotation shaft 16 a of the primary cutter head 16.
Further, as shown in FIG. 4, between the intersection P of the large-diameter circle R1 depicting the rotation locus of the main cutter head 16 and the small-diameter circle R2 depicting the rotation locus of the auxiliary cutter head 24 and the connecting arc portion 7. The main sub cutter 30 and the 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 a rotation shaft 16a of the main cutter head 16 or an appropriate position in the radial direction, and can extend and contract. The main sub-cutter 30 can be partially excavated in a region along the outer shape of the connecting arc portion 7 and removed from the main cutter head 16 while the hydraulic jack 33 is extended.

Similarly, the sub sub cutter 31 is connected to a hydraulic jack 34 that extends radially outward from a rotation shaft 24a of the sub cutter head 24 or an appropriate position in the radial direction and that can extend and contract. The sub sub cutter 31 is capable of excavating an upper region deviated 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. A 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.
Thus, in the region excavated by the main subcutter 30 and the subsubcutter 31, the substantially arc plate-like middle segments 6A and 6 are assembled to the front of the existing segments by joints before and after the direction of tunneling and construct the connecting arc 7 . The connecting arc portion 7 is formed in an arc shape by connecting the end portions of the large diameter arc portion 3 and the small diameter arc portion 5.

  The middle lid partition 10 may be constructed by the elector device 19 simultaneously with the construction of the oval segment ring 1 a consisting of the large diameter arc portion 3, the small diameter arc portion 5 and the connecting arc portion 7 when constructing the sewerage tunnel 1. it can. In this case, since the inner lid partitioning portion 10 is installed at an intermediate height of the egg-shaped segment ring 1a and the inside thereof is partitioned into the upper space 12 and the lower space 13, it is not affected by earth pressure.

The sewer tunnel 1 according to the present embodiment has the above-described configuration, and its usage will be described next.
When the sewer tunnel 1 is used, rainwater etc. flows down into the upper space 12 of the egg-shaped segment ring 1a through the drainage port or manhole etc. and flows mainly downward to the concavely curved inner lid partition 10 and sent downstream. . Even if the amount of water such as rainwater is small, it can be collected at the bottom of the concave surface of the inner lid partition 10 to form a water flow.
On the other hand, the dirty water is drained 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 this time, the bottom portion of the lower space 13 is narrower than the upper space 12 by the small-diameter arc portion 5 and is formed by the circle R1 and the circle R2 having a smaller diameter than the inner lid partition portion 10, so that the amount of sewage is small. It can be collected at the bottom to form a stream of water and flow smoothly.

Moreover, when the worker who performs maintenance management etc. inspects while walking in the upper space 12 of the sewer tunnel 1, the area of the middle segment 6 </ b> A and the inner lid partition part 10 can be walked. Therefore, it is possible to walk without wetting the shoes, to increase the walking speed, and to perform maintenance and inspection efficiently.
When raining or the like, the inner lid partition 10 is opened and a part of the increased water flow in the upper space 12 is allowed to flow into the lower space 13, so that the sewage in the lower space 13 used as a sewage pipe can be flowed and cleaned. . Furthermore, when there is a possibility that the water level of the upper space 12 may increase rapidly due to heavy rain or the like, it is possible to prevent the rainwater from overflowing from the manhole or the like by removing the inner lid partition 10 in advance and flowing it into the lower space 13.

As described above, according to the sewer tunnel 1 and the construction method thereof according to the present embodiment, since the vertical cross-sectional shape is formed into the vertically long egg-shaped segment ring 1a whose diameter is reduced from the upper side to the lower side, a road with a narrow width, etc. It can be laid at the bottom of the building and can be used effectively.
Since the upper space 12 of the egg-shaped segment ring 1a is formed by the inner lid partition 10 and the lower space 13 is formed by the small-diameter arc portion 5, the bottom space 13 is collected at the bottom to secure a water flow even if the amount of rainwater or sewage is small. Can be transported and processed. The rainwater that has increased by removing the inner lid partition 10 in the rainy weather can be flowed into the lower space 13 to clean the lower space 13 and prevent the rainwater from overflowing from the upper space 12 onto the road.

In particular, since the small-diameter arc portion 5 of the lower space 13 is smaller in diameter than the inner lid partition portion 10 of the upper space 12, the water flow rate is obtained by obtaining the water depth even in a low-gradient area where the flow rate is small and it is difficult to ensure the minimum flow rate. It is possible to accelerate and secure stable sweepability.
Furthermore, in the sewer tunnel 1 composed of the egg-shaped segment ring 1a, the inner lid partition 10 separates the upper space (upper pipe line) 12 through which rainwater and the like flow and the lower space (lower pipe line) 13 through which sewage and the like flow, It is possible to reduce the cost of rainwater and sewage treatment at water treatment plants etc.
Moreover, since the upper space 12 and the lower space 13 of the sewer tunnel 1 can be constructed simultaneously, the construction cost is reduced. In addition, since the worker can walk the inner lid partition 10 during the maintenance inspection, the inspection can be efficiently performed without getting the shoes wet.

  As described above, the sewer tunnel 1 and the construction method thereof according to the embodiment of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiment, and appropriate changes and modifications can be made without departing from the spirit of the present invention. Substitution etc. are possible, and all of these are included in the present invention. Although other embodiments and modifications of the present invention will be described below, the same or similar parts and members as those of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

Next, a sewer tunnel 40 according to a second embodiment of the present invention will be described with reference to FIGS. 5 and 6.
The sewer tunnel 40 according to the second embodiment has the same configuration as the sewer tunnel 1 according to the first embodiment. In the present embodiment, the insert bolt 41a is screwed and fixed to the inner surface ceiling of the upper space 12 in the oval segment ring 1a. Similarly, insert bolts 41b were screwed and fixed to both end portions of the inner lid partition portion 10 fitted to the step receiving portions 6b of the middle segment 6A on both sides of the upper space 12, respectively. In addition, the eyebolt 43 is screwed and fixed to the insert bolt 41 a on the inner surface ceiling of the upper space 12. Fixing bolts 42 are fastened to the inner lid partition part 10 and the middle segment 6A to the insert bolts 41b at both ends of the inner lid partition part 10, and the inner lid partition part 10 is fixed.

When the 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, an operator who has inspected the upper space 12 removes the fixing bolts 42 from the insert bolts 41b at both ends of the inner lid partition 10 and tightens the eye bolts 43 respectively. Then, both ends of the eyebolt 43 on the inner surface of the ceiling are engaged with the eyebolts 43 at both ends of the inner lid partition 10 through the chain 45 as a cord-like member. A hook bolt may be attached instead of the eye bolt 43, and these are included in the locking member. The chain block 46 is attached to the chain 45 at an appropriate place.
Then, when the operator pulls up the chain 45 with the chain block 46, the inner lid partition 10 is lifted through 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 sewer 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 10 that partitions the inside of the segment vertically may be fitted and fixed, or may be detachably installed.
Further, in each of the above-described embodiments, both end portions of the large-diameter arc portion 3 and the small-diameter arc portion 5 of the egg-shaped segment ring 1 a are formed by the substantially arc-shaped connecting arc portion 7. The tangents at both ends of the arc portion 3 and the small diameter arc portion 5 may be formed in a linear shape in cross section, and these are included in the connecting portion.

In the above-described embodiments, the inner lid partition portion 10 is formed in an arc shape having a diameter larger than that of the small-diameter arc portion 5, but may be formed so as to have an inner diameter that is the same as or smaller than that of the small-diameter arc portion 5. . Moreover, although the inner lid partition part 10 was formed by connecting a plurality of inner lid segments 10a, it may be formed by a substantially arc plate integrated 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 Egg-shaped segment ring 2 Large-diameter segment 3 Large-diameter arc part 4 Small-diameter segment 5 Small-diameter arc part 6, 6A Middle segment 6b Stepped receiving part 7 Connection arc part 10 Middle lid partition part 11 Shield excavator 12 Upper space (upper pipe line)
13 Lower space (lower pipeline)
16 main cutter head 16a, 24a rotary 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 41 a, 41 b insert bolt 43 eye bolt 45 chain 46 chain block

Claims (5)

An oval or oval segment ring, and
And a middle lid partition part that divides the segment ring into two stages of an upper space and a lower space,
The sewer tunnel characterized in that the inner lid partition part is curved to be convex toward the lower space side. The upper space of the segment ring is divided 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 part, a lower second arc part having a smaller diameter than the first arc part, both side ends of the first arc part and both end parts of the second arc part The sewer tunnel according to claim 1, wherein the sewer tunnel is partitioned by connecting portions that connect the respective portions.   The sewer tunnel according to claim 2, wherein the inner lid partition is detachably installed in the upper space.   The locking member provided in the said inner lid partition part and the cord-like member which opens the said inner lid partition part via the said locking member are described in any one of Claim 1 to 3 Sewer tunnel. While rotating and excavating the ground with a first cutter head equipped with a relatively large diameter cutter bit, and constructing a first arc portion with a segment assembled at the rear thereof, and
The ground was rotated and excavated by the second cutter head, which was partially overlapped in the radial direction on the lower side of the first cutter head and provided with a relatively small-diameter cutter bit, and a segment was assembled at the rear thereof. Building a second arc at the bottom,
Excavate the ground between the intersecting part of the first cutter head and the second cutter head and the arc part or the tangent part connecting the both ends of the first arc part and the second arc part with a sub cutter, and segment behind it. And at the same time, construct a connecting part assembled by
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 cross-sectional shape that protrudes downward, the cross-section is substantially ovoid. The construction method of the sewer tunnel characterized by constructing a segment ring.

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