JP5609053B2 - Tunnel construction method and tunnel constructed by the construction method - Google Patents

Description

  The present invention relates to a tunnel construction method for constructing a new tunnel using an existing tunnel and a tunnel constructed by the construction method.

  In recent years, in order to alleviate traffic congestion due to increased traffic of vehicles, new tunnels have been constructed in parallel with existing tunnels, or existing tunnels have been widened to increase lanes.

  When constructing a new tunnel in parallel with the existing tunnel, generally, as shown in FIG. 9, a new tunnel is constructed at a distance that does not affect the existing tunnel, for example, 20 m or more away. To do.

  In Patent Document 1, as a method for constructing a new approach tunnel connected to an existing tunnel, an approach tunnel is constructed by penetrating the side of the existing tunnel while gradually approaching the existing tunnel with a shield machine. A method is disclosed.

  In addition, as a method for widening an existing tunnel, Patent Document 2 discloses that a protector is installed over the entire line in the existing tunnel, and the ground is excavated on the inner peripheral surface of the existing tunnel while the vehicle is running in the protector. A method of widening is disclosed.

JP 2005-60968 A JP 2002-4756 A

  However, each method described above has the following problems.

  In the method of constructing a new tunnel in parallel with the existing tunnel, the site for building a new tunnel road A (hatched part in Fig. 9) must be acquired. Takes a lot of time and money.

  Moreover, in the method of patent document 1, since the shield machine is utilized, the ground of a hard ground cannot be excavated.

  Furthermore, in the method described in Patent Document 2, since the expensive protector is installed over the entire existing tunnel, the construction cost becomes high.

  Therefore, the present invention has been made in view of the above points, and aims to provide a tunnel construction method excellent in economic efficiency and a tunnel constructed by the construction method without being affected by geology. To do.

The present invention is a tunnel construction method in which a new tunnel is constructed in a natural mountain using an existing tunnel by a mountain construction method.
The existing tunnel is widened from one end of the existing tunnel to a predetermined point determined as a point where the stability of the natural mountain can be secured even if a space in the natural mountain where the size of the cross section changes is formed. By constructing a first widening tunnel portion having a constant cross section having a larger cross section than the existing tunnel,
A second widened tunnel portion having a cross section that gradually increases from the predetermined point toward the deep part of the natural ground is constructed until the cross section of the second widened tunnel portion is large enough to excavate the new tunnel. ,
A branch tunnel portion that branches from the second widened tunnel portion is constructed from the end point of the second widened tunnel portion to the arrival side wellhead of the new tunnel.

  According to the present invention, as shown in FIG. 9, a new tunnel is formed in parallel with the existing existing tunnel by widening the one-end side wellhead of the existing tunnel and using the widened portion as a new tunnel wellhead. Compared to the construction of the road, the land for acquisition for building the new tunnel road A can be made narrower, so the time and cost for the land acquisition can be reduced.

  In addition, since a new branch tunnel branching from the existing tunnel is built from the predetermined point to the new tunnel arrival side wellhead, there is no work in the existing tunnel, and the vehicle is safely driven in the existing tunnel. be able to.

  In addition, since the widened portion and the branch tunnel portion are constructed by the mountain method, a new tunnel can be constructed not only on soft ground but also on solid ground.

In the present invention, the branch tunnel portion may be constructed to be parallel to the existing tunnel when the branch tunnel portion is separated by a predetermined distance or more in the width direction of the existing tunnel.

Further, the present invention relates to a tunnel construction method in which a new tunnel is constructed in a natural mountain using an existing tunnel by a mountain construction method.
From the one end side wellhead of the existing tunnel to the predetermined one end side point in the natural ground, the first widening for constructing the one end side widening tunnel portion having a larger cross section than the existing tunnel by widening the existing tunnel Process,
From the other end side of the existing tunnel to the predetermined other end side point in the natural ground, the other end side widened tunnel portion having a larger cross section than the existing tunnel is constructed by widening the existing tunnel. Two widening steps;
A branch tunnel construction process for constructing a new branch tunnel section in which both ends are branched from the one end side widened tunnel section and the other end side widened tunnel section from the predetermined one end side point to the predetermined other end side point, respectively. It is characterized by providing these.

  Moreover, in this invention, after implementing said 1st widening process, it is good also as implementing the said branch tunnel construction process and said 2nd widening process.

  According to the present invention, after carrying out the first widening step, the second widening step is carried out while carrying out the branch tunnel construction step, so that the construction period is greatly increased. It can be shortened. Therefore, construction costs can be reduced.

  Moreover, in this invention, it is good also as implementing the said branch tunnel construction process, after implementing said 1st widening process and said 2nd widening process.

  According to the present invention, by performing the second widening step while performing the first widening step, the digging is performed, so that the construction period can be greatly shortened. Therefore, construction costs can be reduced.

  The tunnel of the present invention is constructed by the tunnel construction method described above.

  ADVANTAGE OF THE INVENTION According to this invention, the tunnel constructed | assembled by the construction method of the tunnel excellent in economical efficiency, and the construction method can be provided, without receiving to the influence of geology.

It is a top view which shows the new tunnel constructed | assembled with the construction method of the tunnel which concerns on 1st embodiment of this invention. It is A-A 'sectional drawing of FIG. It is B-B 'sectional drawing of FIG. It is C-C 'sectional drawing of FIG. It is D-D 'sectional drawing of FIG. It is F-F 'sectional drawing of FIG. It is a front view which shows the other end side wellhead vicinity of a branch tunnel part. It is a top view which shows the new tunnel constructed | assembled with the construction method of the tunnel which concerns on 2nd embodiment of this invention. It is a top view which shows the state which builds a new tunnel to the side of the existing tunnel by a conventional construction method, and is an enlarged view of the vicinity of a wellhead.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiment, a case where the present invention is applied to a road tunnel will be described. However, the present invention is not limited to this, and can be applied to, for example, a train tunnel.

FIG. 1 is a plan view showing a new tunnel 1 constructed by the tunnel construction method according to the first embodiment of the present invention.
As shown in FIG. 1, the tunnel 1 includes a widened tunnel portion 4 that widens an existing tunnel 3 and a branch tunnel portion 5 that branches from the widened tunnel portion 4. Below, the construction method of this tunnel 1 is demonstrated. First, a construction method of the widening tunnel unit 4 will be described, and then a construction method of the branch tunnel unit 5 will be described.

  The widening tunnel portion 4 is constructed by widening the existing tunnel 3 in a section from one end-side wellhead 2 of the existing tunnel 3 to a predetermined point 6.

  Before performing the widening operation, a protector 7 (a hatched portion with a left-downward slanted line in FIG. 1) is installed in the existing tunnel 3 of the widening tunnel portion 4 so that the vehicle can travel in the existing tunnel 3. From the viewpoint of safety, it is desirable to install the protector 7 so as to protrude slightly inward from the predetermined point 6.

  Next, a space S (shown later in FIG. 2) having a larger cross section than the existing tunnel 3 is constructed by widening the existing tunnel 3 by a mountain method such as blasting or mechanical excavation.

  The widening tunnel portion 4 includes a first section M having a constant cross-sectional size and a second section N in which the cross-sectional size gradually increases. First, the construction method of the first section M will be described, and then the construction method of the second section N will be described.

2 is a cross-sectional view taken along line AA ′ of FIG.
As shown in FIG. 2, the first section M having the above-described space S having a size capable of installing a new roadway 8 by widening the existing tunnel 3 from the one end side wellhead 2 toward the deep part of the natural ground E. To construct.

  The first section M is constructed from the one-end side wellhead 2 to a point where the stability of the natural ground E is low, for example, a point passing through an unconsolidated layer or a weathered layer.

  The reason why the cross section size of the first section M is made constant is that it is technically possible to construct the space S in which the cross section size changes in the formation where the stability of the natural ground E is low. Because there is a high possibility of falling, etc., considering that the existing tunnel 3 is used as a live line, a construction method with a low risk, that is, a construction method with a constant cross-sectional size was selected. is there.

  Next, the construction method of the second section N will be described.

3 and 4 are BB ′ and CC ′ sectional views of FIG. 1, respectively.
As shown in FIG. 3 and FIG. 4, the existing tunnel 3 is widened from the end point of the first section M toward the deep part of the natural ground E, and a second section N whose section gradually increases as it goes deeper is constructed. To do.

  The second section N is constructed from a stable formation in which the strength of the natural ground E can be secured from the end point of the first section M, for example, a point where it becomes a medium hard rock. This is because safety can be ensured even if the space S in which the size of the cross section changes is constructed within a stable formation where the strength of the natural ground E can be ensured.

  In the vicinity of the end point of the second section N, a cross section having a size enough to excavate the branch tunnel 5 ′ (see FIG. 1) is formed on the side of the existing tunnel 3.

  As described above, the first section M of the widening tunnel portion 4 is provided for the purpose of safely constructing the space S in the formation with low stability. The boundary with the section N, that is, the natural ground strength boundary point 6 ′ is provided at the boundary between the low-level formation in the natural ground E and the stable formation capable of securing the strength. The natural ground strength boundary point 6 'is appropriately determined for each site by design or the like based on the result of geological survey or the like.

5 is a cross-sectional view taken along the line DD ′ of FIG.
As shown in FIG. 5, a branch tunnel portion 5 that branches off from the widening tunnel portion 4 is formed by a mountain construction method on the side of the existing tunnel 3 toward the deep part of the natural mountain E from the predetermined point 6. (See FIG. 1) at a predetermined angle.

  Specifically, at the predetermined point 6, excavation of the branch tunnel 5 ′ is started from the existing tunnel 3 to the side, for example, from a position 3 m away, and parallel to the existing tunnel 3, and The branch tunnel portion 5 is constructed so as to gradually move away from the existing tunnel 3 as it goes deeper in the natural ground E. Then, the branch tunnel 5 ′ is excavated at the predetermined angle until the branch tunnel 5 ′ reaches a horizontal distance from the existing tunnel 3, for example, about 20 m away.

6 is a cross-sectional view taken along the line FF ′ of FIG.
As shown in FIG. 6, when the branch tunnel 5 ′ reaches a position about 20 m away from the existing tunnel 3, the direction of the branch tunnel 5 ′ is changed and excavated in parallel to the existing tunnel 3, thereby Build part 5.

  And the other end side wellhead 11a of branch tunnel 5 'is constructed in the side of the other end side wellhead 11b of the existing tunnel 3, as shown in FIG.

Thereafter, a new carriageway 8 is laid in the first section M, and the widened portion is used as a part of the tunnel 1.
Finally, the protector 7 is removed to make it possible to run.

  According to the construction method of the tunnel 1 in the present embodiment described above, the protector 7 is installed in the existing tunnel 3 from the one-end wellhead 2 of the existing tunnel 3 to the predetermined point 6 in the natural ground E. Therefore, the vehicle can be closed only for a short period of time when the protector 7 is installed. After the installation, the vehicle can always be run while the vehicle is running. Furthermore, from the predetermined point 6 toward the deep part of the natural ground E, the branch tunnel part 5 branched from the widening tunnel part 4 is newly constructed, so that the vehicle can be safely kept without blocking the existing tunnel 3. It can be run.

  Moreover, since the protector 7 is installed from the one-end wellhead 2 of the existing tunnel 3 to the predetermined point 6 in the ground E, it is more economical than the case where the protector 7 is installed on the entire existing tunnel 3 line.

  In addition, by constructing the tunnel 1 by widening the one-end side wellhead 2, a new tunnel road A (see FIG. 9) is constructed as compared with the case where the tunnel is constructed in parallel with the existing existing tunnel 3. In order to reduce the time and cost for acquiring a land, particularly in public works, it is possible to reduce the size of the land for acquisition.

  Moreover, since the widening tunnel part 4 and the branch tunnel part 5 are constructed by the mountain method, the tunnel 1 can be constructed not only on the soft ground but also on the ground E of the hard ground.

  In the present embodiment, the case where the branch tunnel portion 5 is constructed in parallel from a position approximately 20 m away from the existing tunnel 3 in the horizontal direction has been described. However, the present invention is not limited to this value. It is only necessary to be far enough so as not to affect the existing tunnel 3 when the branch tunnel 5 ′ is excavated, and is appropriately determined for each site by design based on the result of geological survey or the like. Therefore, the branch tunnel portion 5 may be continuously constructed in parallel with the predetermined angle in the direction away from the existing tunnel 3 without being constructed in parallel.

  Next, a second embodiment of the present invention will be described. In the following description, portions corresponding to the first embodiment are denoted by the same reference numerals, description thereof is omitted, and differences are mainly described. In the second embodiment, similarly to the one end side wellhead 2, the other end side wellhead 11 widens the existing tunnel 3 by the widening method, and uses this widened portion as a part of the new tunnel 21.

FIG. 8 is a plan view showing a new tunnel 21 constructed by the tunnel construction method according to the second embodiment of the present invention.
As shown in FIG. 8, the tunnel 21 includes a first widened tunnel portion 24a and a second widened tunnel portion 24b that widen the existing tunnel 3, and a branched tunnel portion 25 that connects these widened tunnel portions 24a and 24b, Consists of Below, the construction method of this new tunnel 21 is demonstrated.

  First, as shown in the first embodiment, the first widened tunnel portion 24a is constructed by widening the existing tunnel 3 from the one end side wellhead 2 of the existing tunnel 3 to the predetermined one end side point 26a (first). Widening process).

Moreover, the 2nd widening tunnel part 24b is constructed | assembled by widening the existing tunnel 3 by the same construction method as 1st Embodiment from the other end side wellhead 11 of the existing tunnel 3 to the predetermined | prescribed other end side point 26b ( Second widening step). In other words, the first widening tunnel portion 24a is constructed, and the second widening tunnel portion 24b is constructed, so-called digging is performed.
It should be noted that the natural ground strength boundary point 26a 'on one end side and the natural ground strength boundary point 26b' on the other end side are stable and can secure a stratum and low strength in the natural ground E, as in the first embodiment. It is established at the boundary with the stratum.

  After the construction of the first and second widened tunnel portions 24a and 24b, the branch tunnel 25 'is excavated from the first and second widened tunnel portions 24a and 24b, respectively, as in the first embodiment. The branch tunnel part 25 is constructed in the vicinity of the central part (branch tunnel construction process).

  According to the construction method of the tunnel 21 in the present embodiment described above, the construction period can be significantly shortened by performing the digging. Therefore, construction costs can be reduced.

  Further, by constructing a new tunnel 21 by widening the one end side wellhead 2 and the other end side wellhead 11, compared with the case where a tunnel is constructed in parallel with the existing existing tunnel 3, the both sides of the tunnel 21. Since the site for acquisition for building a new tunnel road A (see FIG. 9) can be small, particularly in public works, the time and cost for acquiring the site can be reduced.

  Furthermore, in addition to the effects described above, the present embodiment can provide the same effects as those of the first embodiment.

  In addition, in this embodiment, although the case where a branch tunnel construction process is implemented after implementing a 1st widening process and a 2nd widening process was demonstrated, it is not limited to this, The 1st widening process After carrying out, the branch tunnel construction step and the second widening step may be carried out.

DESCRIPTION OF SYMBOLS 1 Tunnel 2 One end side wellhead 3 Existing tunnel 4 Widening tunnel part 5 Branch tunnel part 5 'Branch tunnel 6 Predetermined point 6' Ground strength boundary point 7 Protector 8 New roadway 11 Other end side wellhead 11a The other end of a new tunnel Side wellhead 11b Other end wellhead of existing tunnel 21 Tunnel 24a First widened tunnel portion 24b Second widened tunnel portion 25 Branch tunnel portion 25 'Branch tunnel 26a Predetermined one end side point 26b Predetermined other end side point 26a' One end side Natural ground strength boundary point 26b 'Natural ground strength boundary point E on the other end side Natural ground M First section N Second section S Space

Claims (6)

In the tunnel construction method that uses the existing tunnel to build a new tunnel in the natural mountain by the mountain method,
The existing tunnel is widened from one end of the existing tunnel to a predetermined point determined as a point where the stability of the natural mountain can be secured even if a space in the natural mountain where the size of the cross section changes is formed. By constructing a first widening tunnel portion having a constant cross section having a larger cross section than the existing tunnel,
A second widened tunnel portion having a cross section that gradually increases from the predetermined point toward the deep part of the natural ground is constructed until the cross section of the second widened tunnel portion is large enough to excavate the new tunnel. ,
A tunnel construction method characterized by constructing a branch tunnel portion that branches from the second widened tunnel portion from the end point of the second widened tunnel portion to the arrival side wellhead of the new tunnel. 2. The tunnel according to claim 1, wherein when the branch tunnel portion is separated by a predetermined distance or more in the width direction of the existing tunnel, the branch tunnel portion is constructed to be parallel to the existing tunnel. Construction method. In the tunnel construction method that uses the existing tunnel to build a new tunnel in the natural mountain by the mountain method,
From the one end side wellhead of the existing tunnel to the predetermined one end side point in the natural ground, the first widening for constructing the one end side widening tunnel portion having a larger cross section than the existing tunnel by widening the existing tunnel Process,
From the other end side of the existing tunnel to the predetermined other end side point in the natural ground, the other end side widened tunnel portion having a larger cross section than the existing tunnel is constructed by widening the existing tunnel. Two widening steps;
A branch tunnel construction process for constructing a new branch tunnel section in which both ends are branched from the one end side widened tunnel section and the other end side widened tunnel section from the predetermined one end side point to the predetermined other end side point, respectively. A tunnel construction method characterized by comprising: The tunnel construction method according to claim 3 , wherein the branch tunnel construction step and the second widening step are performed after the first widening step.   The tunnel construction method according to claim 3, wherein the branch tunnel construction step is performed after the first widening step and the second widening step. A tunnel constructed by the tunnel construction method according to any one of claims 1 to 5 .

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