JP6252842B2 - Construction method of outer shield tunnel - Google Patents

Description

  The present invention relates to an outer shell shield tunnel construction method.

  Conventionally, when constructing a large cross-section tunnel, a number of small cross-section shield tunnels are arranged in advance along the contour, and after connecting the small cross-section tunnels and constructing a covering body for the outer shell shield tunnel, A method of excavating the inside of the shell shield tunnel to complete a large section tunnel has been proposed.

  For example, Patent Document 1 discloses that the leading tunnel and the trailing tunnel having a small cross section are alternately arranged and integrated in a state in which a part of the lining bodies is polymerized, and the lining bodies of both sides are integrated. A construction method has been proposed in which a tunnel structure having a structure connected by a reinforcing material is constructed, and the inside of the tunnel is excavated to complete a large section tunnel.

Japanese Patent No. 4687986

However, the conventional large-section tunnel construction method described above has the following problems.
In other words, when connecting the preceding and succeeding tunnels of the outer shell shield tunnel, the target ground between the two adjacent tunnels is collapsed by the auxiliary method such as the freezing method or the chemical injection method and the abnormal water discharge. In order to prevent this, the segment located between the two tunnels is removed to perform the opening.
However, if the target ground is solidified clay and the sand layer is partially interposed, using the freezing method increases the freezing expansion pressure of the solidified clay, which affects existing nearby structures. It was.
In addition, when the ground of the construction site of the outer shell shield tunnel is at a high water pressure, sufficient water stoppage could not be achieved by the chemical injection method alone, resulting in abnormal water outflow, possibly causing sediment collapse. .

  The present invention has been made in view of the above-described problems, and can easily and surely stop the connection part between tunnels regardless of the ground conditions, and is effective for the ground where the freezing method cannot be applied. The object is to provide an outer shell shield tunnel construction method that can be adopted.

To achieve the above object, the method of constructing the outer shell shield tunneling according to the present invention, when building a large section tunnel with underground cavities by drilling a ground, the contour of the ground cavity should be constructed The outer shield tunnel is divided into a preceding tunnel and a following tunnel, and arranged alternately, and the outer shell covering wall of the large section tunnel along the outer shield tunnel is constructed. A method of constructing an outer shell shield tunnel that excavates the inside of the shell lining wall to build the underground cavity, and can be cut by a shield machine at intervals along the contour of the underground cavity A step of constructing a leading tunnel by arranging a leading segment, a step of filling a filler that can be cut with a shield machine in the leading tunnel, and a cross section between the preceding tunnels overlapping each other. A step of constructing a trailing tunnel by arranging a trailing segment while cutting a part of the leading segment in the manner described above, and a step of injecting a backfill material to the back of the leading segment and the trailing segment If, have a, wherein the preceding segment, the pressing member is provided for supporting the connecting end portion of said trailing segment from below, the pressing member, the prior is fixed to the outer peripheral surface of the trailing segment It is characterized by supporting the inner peripheral surface of the segment .

  In the present invention, the succeeding segment can be arranged by cutting with a shield machine that constructs the succeeding tunnel so that the cross sections of the preceding tunnels overlap each other. Thereby, a preceding tunnel and a succeeding tunnel can be connected, and the outer shell shield tunnel formed from the preceding tunnel and the succeeding tunnel having a shape along the contour of the underground cavity can be constructed. At this time, the preceding tunnel is filled with a cutting material and the shape of the preceding segment is held from the inside, so that the preceding segment is loaded with the cutting of the shield tunneling machine for the subsequent tunnel. It is possible to prevent deformation due to.

In addition, since the deformation is suppressed by filling the leading tunnel with the filler, it is possible to prevent the formation of a gap at the connection portion between the preceding segment and the succeeding segment. Therefore, it is possible to prevent the natural ground from being exposed in the outer shell shield tunnel, and to prevent the groundwater in the ground from flowing into the tunnel from the connection portion. Therefore, it is possible to carry out the slitting operation for removing the portion located in the preceding segment of the succeeding segment by a simple method without adopting the conventional freezing method, and the inside of the preceding tunnel and the succeeding tunnel are communicated with each other. Can be made. Furthermore, since the freezing method is not required, the freezing expansion pressure increases when the freezing method is performed on the geology such as solidified clay, and the inconvenience of affecting the existing existing structures can be eliminated.
In the present invention, since the connecting end portion of the preceding segment connected to the succeeding segment is supported from below by the pressing member, the preceding segment slides on the succeeding segment by the load or water pressure received from the ground. It can suppress pushing out to the sky side. Therefore, it is possible to prevent the positional shift between the preceding segment and the succeeding segment and to secure the inner air cross section of the outer shield tunnel. Furthermore, since the injection pressure of the backfilling material can be increased, there is an advantage that reliable injection can be performed on the connection portion between the preceding segment and the succeeding segment.

  Further, in the construction method of the outer shell shield tunnel according to the present invention, the step of disposing the expansion bag body having pressure resistance on the connection surface between the preceding segment and the succeeding segment and inflating the expansion bag body. It is preferable to have.

In addition, immediately after the construction of the rear tunnel, by inflating the inflatable bag provided on the connection surface between the preceding segment and the rear segment, the connection portion becomes water-tight, and the back of the outer shield tunnel Sufficient backfill injection can be performed, and the gap at the connection portion can be closed. Therefore, it is possible to prevent the natural ground from being exposed in the outer shell shield tunnel, and to prevent the groundwater in the ground from flowing into the tunnel from the connection portion.
Thus, by using the expansion bag body in the outer shell shield tunnel, it becomes possible to stop water more reliably regardless of the geological conditions of the ground.

  Moreover, in the construction method of the outer shell shield tunnel according to the present invention, it is preferable that a water stop material is injected into the ground on the back side of the connection portion between the preceding segment and the succeeding segment.

  In the present invention, the connecting portion between the preceding segment and the succeeding segment is connected in a watertight state without any gap due to the expansion of the airbag, so that a water stop material can be injected into the ground on the back of the connecting portion. it can. Thereby, in addition to a backfill material, the water stop effect by a water stop material can be heightened, and effective water stop can be performed even when a target ground turns into high pressure water.

  In the outer shield tunnel construction method according to the present invention, it is preferable that the succeeding segment has a smaller diameter than the preceding segment.

  In this case, since the preceding tunnel is larger in diameter than the succeeding tunnel, the cutting ratio of the succeeding tunnel in the succeeding tunnel by the shield tunneling machine is reduced, and the influence due to the cutting of the preceding tunnel can be suppressed.

  Moreover, in the construction method of the outer shell shield tunnel according to the present invention, it is preferable to fill the filler after building a part of the outer shell covering wall in the preceding tunnel.

In the present invention, since a part of the outer shell lining wall can be built in advance in a region not cut by the shield tunneling machine of the succeeding tunnel in the preceding tunnel, the preceding segment and the succeeding segment are connected, The construction efficiency can be increased as compared with the case where the outer wall is built after removing the filler in the tunnel.
Furthermore, since the filler filled in the preceding tunnel only needs to be filled in a gap around a part of the outer shell lining wall, there is an advantage that the amount of filler used can be reduced.

  Moreover, in the construction method of the outer shell shield tunnel according to the present invention, it is preferable that the segment that can be cut out of the preceding segments is arranged in a portion that is cut by a shield machine that constructs the subsequent tunnel.

  In this case, since the use location of the expensive segment which can be cut with a shield machine is limited to the part cut with a subsequent tunnel, the increase in member cost can be suppressed.

  According to the construction method of the outer shield tunnel of the present invention, it is possible to eliminate the exposure of the natural ground at the connection portion between the preceding tunnel and the succeeding tunnel. Therefore, when the segment is cut open, the connection portion between the tunnels can be easily and reliably stopped regardless of the ground conditions, and can be effectively used for the ground to which the freezing method cannot be applied.

It is sectional drawing which shows the outline | summary of the construction method of the large section tunnel by embodiment of this invention. (A)-(c) is sectional drawing which shows the construction process of an outer shell shield tunnel. (A)-(c) is sectional drawing which shows the construction process following FIG.2 (c). It is a perspective view which shows the open state of the connection part of a preceding tunnel and a succeeding tunnel. It is principal part sectional drawing which shows the inflated state of the airbag in the connection part of a preceding tunnel and a succeeding tunnel.

  Hereinafter, the construction method of the outer shell shield tunnel according to the embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the outer shell shield tunnel 1 according to the present embodiment is constructed by a seal excavator, for example, when constructing a large section tunnel 1A that forms an underground cavity K such as a large section road tunnel. A large number (20 in FIG. 1) are provided along the outline (outer shell) of the large-section tunnel 1A. The large-section tunnel 1A forms an outer shell covering wall R having a substantially elliptical shape with the long axis extending in the horizontal direction through the outer shell shield tunnel 1. The substantially elliptical frame structure R is made of, for example, reinforced concrete and may be constructed on site, or a precast concrete made of a synthetic segment, for example, manufactured in a factory or the like can be used.

  The outer shield tunnel 1 includes a large number (10 in FIG. 1) of preceding tunnels 10 and a large number (10 in FIG. 1) of the following tunnels 20 along the outer shell. Alternatingly arranged. The centers O1 and O2 of the preceding tunnel 10 and the succeeding tunnel 20 are located on the outer shell.

  As shown in FIGS. 2 (a) to 2 (c), the outer shield tunnel 1 is first preceded by a plurality of preceding tunnels 10 spaced apart from each other along the outline of the large section tunnel 1A to be finally built. Let it work. At this time, a predetermined interval for constructing the succeeding tunnel 20 in a subsequent process is secured between the preceding tunnels 10 and 10. This predetermined interval is smaller than the outer diameter dimension of the trailing tunnel 20 and is set to a predetermined dimension in which the left and right sides of the trailing tunnel 20 overlap the preceding tunnel 10 respectively. And the backfill material 6 (refer FIG. 5) is inject | poured into the back surface of the preceding segment 10. FIG.

  Next, as shown in FIGS. 3A to 3C, the subsequent tunnel 20 is constructed by the shield method so that the cross-sections overlap each other between the preceding tunnels 10. The 20 segments 10a and 20a are connected together. Finally, all the preceding tunnels 10 and the following tunnels 20 are alternately connected in the circumferential direction of the large section tunnel 1A (see FIG. 1).

  Here, the preceding segment 10a of the preceding preceding tunnel 10 is formed from a segment that can be cut by a shield machine (not shown) that constructs the following tunnel 20 (hereinafter referred to as a cutting segment 10a). As this cuttable segment, for example, a structure using cuttable carbon fiber concrete can be used. The segment that can be cut may be the entire circumference of the preceding tunnel 10, but only a part of the segment 10d that is cut by the trailing tunnel 20 (two-dot chain line portion shown in FIG. 3A). preferable.

  As shown in FIG. 2B, a part of the outer shell lining wall R (first lining wall R1) is built in the preceding preceding tunnel 10. Subsequently, as shown in FIG. 2C, the inside of the preceding tunnel 10 is filled with a filler 3 that can be cut by a shield machine of the subsequent tunnel 20 such as fluidized soil. The filling operation at this time is performed inside the preceding tunnel 10 and is constructed so that the filler 3 is filled at least in front of the face position at the front end of the excavation tunnel 20.

  As shown in FIG. 3A, while cutting a part of the preceding segment 10a (segment 10d) so that the cross sections of the preceding tunnels 10 and 10 overlap each other, The following tunnel 20 is constructed by arranging.

  At this time, as shown in FIG. 4, the expansion bag body 4 having pressure resistance is arranged on the connection surface between the preceding segment 10a and the succeeding segment 20a, and a filling member such as mortar is provided in the expansion bag body 4. Inflate by pressure filling. Here, on the outer peripheral surface 20b of the succeeding segment 20a, the expansion bag body 4 is mounted at a location where the circumferential end face 10c of the preceding segment 10a contacts.

  The expansion bag body 4 extends along the tunnel axial direction X, extends along the circumferential direction on the rear end side (opposite to the face side) of the shield tunneling machine 20A of the subsequent tunnel 20, and includes a subsequent segment. It is accommodated in an unfilled state in a concave groove 20c formed on the outer peripheral surface of 20a. At this time, the unfilled inflatable bag body 4 is in a state of not projecting from the outer peripheral surface 20b, and as shown in FIG. 5, bulges outward from the outer peripheral surface 20b with the filling member filled. And in this bulging state, the expansion bag body 4 is in close contact with the fracture end face 10c of the preceding segment 10a in a watertight manner.

  As shown in FIG. 5, the preceding segment 10a is provided with a pressing metal 5 (pressing member) that supports a connecting end portion with the following segment 20a from below. The presser metal 5 has a shape bent at a predetermined angle, and comes into contact with the first support plate 51 fixed to the outer peripheral surface 20b of the succeeding segment 20a by a bolt and the inner peripheral surface 10b of the preceding segment 10a from below. And a second support plate 52. The presser metal 5 may be provided with a gap in the tunnel axis direction X, or extends linearly along the tunnel axis direction X (see FIG. 4) and fixed with bolts with a gap. It may be a thing. The preceding segment 10a cut and divided by the shield machine that constructs the trailing tunnel 20 is in a state in which the fracture end surface 10c is placed on the trailing segment 20a (outer peripheral surface 20b), and the outer peripheral surface thereof. It is possible to prevent sliding down along the curved surface 20b.

  Next, as shown in FIGS. 4 and 5, the backfill material 6 is injected into the natural ground side on the back surface of the succeeding segment 20. That is, the backfill material 6 is injected only from the inside of the following tunnel 20 into the ground except for the portion overlapping the preceding tunnel 10. At this time, the connection portion T between the preceding segment 10a and the succeeding segment 20a is intimately contacted by the expansion bag body 4, so that the inflow of the backfill material 6 on the natural mountain side into the tunnel is suppressed.

The backfill material 6 may be injected before the expansion bag body 4 is inflated after the assembly of the succeeding segment 20 depending on the state of the ground and the contact state between the fractured end surface 10c of the preceding segment 10a and the succeeding segment 20. You may go to
In addition, when it is determined that sufficient water stoppage is maintained by the injection of the backfill material 6, the installation of the expansion bag body 4 may be omitted. Or it can also be set as the method of not inflating, without filling the filling member in the expansion bag body 4 installed.

In the present embodiment, as shown in FIG. 5, an injection pipe (not shown) is driven into the ground outside the connecting portion T between the preceding segment 10 and the succeeding segment 20 from within the succeeding tunnel 20, The water-stopping material 7 is injected through the injection pipe to improve the ground, thereby forming a water-stopping region, thereby ensuring water-stopping at the connecting portion T. The injection of the water-stopping material 7 may be appropriately performed as necessary, and may be omitted.
In addition, when inject | pouring the water stop material 7, it is preferable to fill with the filling member to the expansion bag body 4 like this Embodiment, and to make it the inflated state.

  Next, as shown in FIG. 3B, the trailing segment 20a located in the preceding tunnel 10 is dismantled and removed, and the leading tunnel 10 and the trailing tunnel 20 are communicated with each other through the formed opening. Become. That is, the outer shell shield tunnel 1 communicating with the outer shell portion is formed. In addition, it is preferable to use a steel segment in advance for the part to be dismantled or to adopt a joint based on the premise of dismantling.

  Next, as shown in FIG. 3C, a part of the outer shell lining wall R (first lining wall R <b> 1) that is built in advance in the preceding tunnel 10 is continued using the opened space. The outer shell lining wall (second lining wall R2) is constructed. The second lining wall R2 may be a reinforced concrete structure, and reinforcement, formwork, and other necessary related operations may be appropriately performed before and after the construction.

  Through the above steps, the outer shell lining wall R of the large-section tunnel 1A to be constructed has been constructed in advance, so the ground inside the outer shell lining wall R is excavated to form the underground cavity K Then, the large section tunnel 1A is completed.

Next, the action and effect by implementing the construction method of the outer shell shield tunnel mentioned above is demonstrated in detail based on drawing.
As shown in FIG. 1, in the present embodiment, a shield machine 20A that constructs the subsequent tunnel 20 so that the cross-sections overlap each other between the preceding tunnels 10 and 10 constructed with a space therebetween. The trailing segment 20 can be arranged by cutting (see FIG. 4). Thereby, the preceding tunnel 10 and the succeeding tunnel 20 can be connected, and the outer shield tunnel 1 formed by the preceding tunnel 10 and the succeeding tunnel 20 having a shape along the outline of the underground cavity K is constructed. can do. At this time, the preceding tunnel 10 is filled with the cutting material 3 that can be cut and the shape of the preceding segment 10 is held from the inside, so that the preceding segment is cut along with the cutting of the shield tunneling machine 20A for the following tunnel 20. It is possible to prevent deformation due to a load applied to 10a.

Moreover, since the deformation | transformation is suppressed by filling the filler 3 in the preceding tunnel 10, it can prevent that a clearance gap is formed in the connection part T of the preceding segment 10 and the succeeding segment 20. FIG. Therefore, it is possible to prevent the natural ground from being exposed in the outer shell shield tunnel 1 and to prevent the groundwater in the ground from flowing into the tunnel 1 from the connection portion T.
Furthermore, immediately after the construction of the trailing tunnel 20, as shown in FIG. 5, the airbag 4 provided on the connection surface between the preceding segment 10a and the trailing segment 20a is inflated, so that the connecting portion T becomes watertight. Thus, a sufficient amount of the backfilling material 6 can be injected into the back surface of the outer shell shield tunnel 1, and the gap of the connection portion T can be closed. Therefore, it is possible to prevent the natural ground from being exposed in the outer shell shield tunnel 1 and to prevent the groundwater in the ground from flowing into the tunnel 1 from the connection portion T.

  Thus, by using the airbag 4 in the outer shell shield tunnel 1, water can be surely stopped regardless of the geological conditions of the ground. Therefore, the slitting operation for removing the portion located in the preceding segment 10a of the succeeding segment 20a can be performed by a simple method without adopting a conventional freezing method. The inside can be communicated. Furthermore, since the freezing method is not required, the freezing expansion pressure increases when the freezing method is performed on the geology such as solidified clay, and the inconvenience of affecting the existing existing structures can be eliminated.

Further, in the present embodiment, since the connecting end portion of the preceding segment 10a connected on the succeeding segment 20a is supported from below by the presser foot 5, the preceding segment 10a is moved by the load or water pressure received from the ground. It is possible to suppress sliding on the segment 20a and pushing out toward the inner space.
Therefore, it is possible to prevent the positional deviation between the preceding segment 10a and the succeeding segment 20a and to secure the inner cross section of the outer shell shield tunnel 1. Furthermore, since the injection pressure of the backfill material 6 can be increased, there is an advantage that reliable injection can be performed on the connection portion between the preceding segment 10a and the succeeding segment 20a.

  Moreover, since the connection part of the preceding segment 10a and the succeeding segment 20a is connected in a watertight state without a gap due to the expansion of the airbag 4, the water blocking material 7 is injected into the ground on the back surface of the connection part. be able to. Thereby, in addition to the backfill material 6, the water stop effect by the water stop material 7 can be heightened, and even when the target ground becomes high-pressure water, effective water stop can be performed.

  Further, in the present embodiment, since the leading tunnel 10 has a larger diameter than the trailing tunnel 20, the rate of cutting by the shield machine 20A (see FIG. 4) of the trailing tunnel 20 of the leading segment 10a is reduced. The influence of cutting the preceding tunnel 10 can be suppressed.

Furthermore, since a part of the outer shell lining wall R (first lining wall R1) can be built in advance in a region not cut by the shield machine 20A of the succeeding tunnel 20 in the preceding tunnel 10, The construction efficiency can be increased as compared with the case where the outer shell covering wall R is constructed after the segment 10a and the trailing segment 20a are connected and the filler 3 in the preceding tunnel 10 is removed.
Furthermore, since the filler 3 filled in the preceding tunnel 10 should just be filled into the clearance around the 1st lining wall R1, there exists an advantage which can reduce the usage-amount of the filler 3. FIG.

  Further, in the construction method according to the present embodiment, the segment that can be cut out of the preceding segment 10a is arranged at the portion to be cut by the shield machine 20A that constructs the trailing tunnel 20, and therefore the cutting is performed by the shield machine 20A. A possible use location of the expensive segment is limited to a portion cut by the trailing tunnel 20, and an increase in member cost can be suppressed.

As described above, in the construction method of the outer shield tunnel according to the present embodiment, the connection portion T of the preceding tunnel 10 and the subsequent tunnel 20 is connected in a watertight state by the expansion of the expansion bag body 4, and therefore the connection portion thereof. The exposure of natural ground at T can be eliminated.
Therefore, when the segment is cut open, the connection portion T between the tunnels 10 and 20 can be easily and reliably stopped regardless of the ground conditions, and is effectively employed for the ground where the freezing method cannot be applied. I can.

As mentioned above, although embodiment of the construction method of the outer shell shield tunnel by this invention was described, this invention is not limited to said embodiment, In the range which does not deviate from the meaning, it can change suitably.
For example, in this embodiment, it is assumed that 20 outer shield tunnels 1 are constructed with 10 leading tunnels 10 and 10 following tunnels 20, respectively. What is necessary is just to set appropriately according to the magnitude | size and cross-sectional shape of 1 A of large cross-section tunnels to be performed, and the radial dimension of the preceding tunnel 10 and the succeeding tunnel 20 is not limited. For example, in the present embodiment, the front and rear tunnels 10 have a larger diameter than the subsequent tunnel 20, but the present invention is not limited thereto, and the same diameter may be used. Moreover, what is necessary is just to set the space | interval of the preceding tunnels 10 constructed ahead of time according to the diameter dimension of the succeeding tunnel 20.

  In the present embodiment, a part of the outer shell lining wall R (first lining wall R1) is arranged in advance inside the preceding tunnel 10 before the subsequent tunnel 20 is dug, and the first lining wall is arranged. Although the filler 3 is filled around R1, it is not limited to such a construction method. For example, without providing the first lining wall R1 inside the preceding tunnel 10, the filler 3 is filled in the entire inner area, the succeeding tunnel 20 is connected to the preceding tunnel 10, and the segment is cut open. A method of removing the filler 3 in the tunnel 10 and building the outer shell lining wall R (the first lining wall R1 and the second lining wall R2) in the outer shell shield tunnel 1 may be used.

Furthermore, in the present embodiment, a solidified material such as mortar is used as a filling member to be filled in the inflatable bag body 4. However, the present invention is not limited to this, and a liquid such as air or water is also filled. It can be employed as a member. In short, the connecting surface of the leading segment 10 and the trailing segment 20 is made watertight without gaps by the expansion of the expansion bag body 4, and the backfill material 6 and the water stop material 7 to be injected into the ground, the high pressure water ground What is necessary is just to become the structure which can prevent the water discharge in.
Moreover, when it is judged that there is almost no water discharge, the expansion bag body 4 which has pressure | voltage resistance can also be abbreviate | omitted.

  In the present embodiment, the presser bar 5 is used to support the preceding segment 10 from below, but the shape, size, quantity, and the like of the presser bar 5 can be changed as appropriate. Can be omitted.

  Furthermore, in the present embodiment, an example of construction for injecting the water-stopping material 7 in addition to the injection of the backfilling material 6 is shown, but of course the injection of the water-stopping material 7 may be omitted depending on the ground conditions. It is possible to set the injection range as appropriate.

  In addition, it is possible to appropriately replace the components in the above-described embodiments with known components without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Outer shell tunnel 1A Large section tunnel 3 Filler 4 Expansion bag body 5 Pressing metal (pressing member)
6 Backfill material 7 Water stop material 10 Leading tunnel 10a Leading segment 20 Trailing tunnel 20A Shield tunneling machine 20a Trailing segment K Underground cavity R Outer shell lining wall R1 First lining wall R2 Second lining wall T Connection part X Tunnel axial direction

Claims (6)

When building a large section tunnel with underground cavities by drilling a ground, by classifying the shell shield tunnel prior tunnel and the following tunnel along the contour of the ground cavity to be constructed, alternating The outer shell for constructing the underground cavity by excavating the inside of the outer shell covering wall, constructing the outer shell covering wall of the large section tunnel along the outer shield tunnel A method for constructing a shield tunnel,
Constructing a preceding tunnel by placing a preceding segment that can be cut with a shield machine at intervals along the contour of the underground cavity,
Filling the preceding tunnel with a filler that can be cut with a shield machine;
While cutting a part of the preceding segment so that the cross-sections of the preceding tunnels overlap each other, constructing the trailing tunnel by arranging the trailing segment;
Injecting a backfill material into the back of the preceding and following segments;
I have a,
The preceding segment is provided with a pressing member that supports a connection end with the following segment from below.
The pressing member is fixed to the outer peripheral surface of the succeeding segment and supports the inner peripheral surface of the preceding segment .   The outer shell shield according to claim 1, further comprising a step of disposing an inflatable bag body having pressure resistance on a connection surface between the preceding segment and the succeeding segment, and inflating the inflatable bag body. Tunnel construction method. The construction method of the outer shell shield tunnel according to claim 1 or 2 , wherein a water stop material is injected into the ground on the back side of the connecting portion between the preceding segment and the following segment. The construction method of the outer shell shield tunnel according to any one of claims 1 to 3 , wherein the succeeding segment has a smaller diameter than the preceding segment. The construction method of the outer shell shield tunnel according to any one of claims 1 to 4 , wherein the filler is filled after a part of the outer shell lining wall is built in the preceding tunnel. . The outer segment according to any one of claims 1 to 5 , wherein a segment that can be cut among the preceding segments is arranged at a portion that is cut by a shield machine that constructs the subsequent tunnel. Shell shield tunnel construction method.

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