JP2013245533A - Reinforcing method for proximity mountain tunnel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reinforcing method for a proximity mountain tunnel which can: secure stability of ground at a pillar section in a pilot tunnel by reinforcing the same with a structure which is easily installed or removed; and reduce a construction period and a construction cost.SOLUTION: A reinforcing method for a proximity mountain tunnel reinforces a first tunnel 1A when excavating mountain tunnels comprising the first tunnel 1A and a second tunnel 1B juxtaposed to each other. After excavating the first tunnel 1A, the reinforcing method of the proximity mountain tunnel: leans a plurality of steel material 21 against a tunnel side face along a forward direction of the tunnel with a distance from a side wall surface of a pillar section 1P; creates a wall body section 20 by closing spaces between neighboring steel materials 21 with partition plates 22; and fills a space between the wall body section 20 and the side wall surface of the pillar section 1P with fluidized soil 23.

Description

  The present invention relates to a reinforcing method in a close mountain tunnel.

Conventionally, in the construction of mountain tunnels, the independence of surrounding ground has been the basis for ensuring the stability of the tunnel. Further, when a close mountain tunnel such as a two-lane road where the distance between the advanced mine and the reverse mine is 6 m or less is constructed, the influence of proximity appears in the tunnel support structure. In other words, during excavation of the reverse pit, excessive stress is generated in the support member near the pillar portion of the advanced mine, so it is impossible to ensure stability during excavation with only the normal support member, and the natural ground of the pillar portion is If destroyed, the stability of the entire tunnel, including the reverse shaft, may be reduced.
For this reason, the ground of the pillar located between the two tunnels is improved in advance, such as by injecting chemicals, and the support structure of the advanced mine is made more resistant to improve the mechanical stability of the tunnel support structure. Securing is performed (for example, refer to Patent Document 1).

The above-mentioned advance ground improvement in the natural area of the pillar part is an improvement that is injected from the ground surface in advance to the natural area of the pillar part when the earth pressure acting from above exceeds the strength of the natural area of the pillar part. It is common.
In addition, when the bearing capacity of the advanced mine support structure is to be increased, the advanced mine support structure will be affected by the excavation of the reverse mine, so the support structure of the advanced mine shall have a structure with higher proof stress than the reverse mine. To ensure mechanical stability.

JP 2007-32490 A

However, the conventional method for reinforcing a pillar portion in a nearby mountain tunnel has the following problems.
That is, the improvement of the natural ground for the pillar portion has a problem that construction is large and takes time and effort.
Moreover, in the case of the reinforcement method for increasing the bearing strength of the conventional advanced mine support structure, it is possible to reinforce with a combination of steel support construction, shotcrete, and reinforced concrete (RC) structure, or use tie rods, PC steel bars, etc. It becomes reinforcement by tensioning the pillar part of the wall surface of the advanced mine, and after this reinforcement, the excavation of the backward mine is performed, but there is a problem that the installation and removal for the reinforcement become large, and the construction period and construction cost increase. .
In particular, when the depth of the advanced mine and the reverse mine are different, it is common to excavate the upper tunnel first, but the natural ground when excavating the lower mine is extremely low. It was unstable.

  The present invention has been made in view of the above-described problems, and by reinforcing the pillar portion in the advanced mine with a reinforcing structure that is easy to install and remove, the stability of the natural ground of the pillar portion can be ensured. At the same time, it is an object to provide a method for reinforcing a close mountain tunnel that can reduce the construction period and the construction cost.

  In order to achieve the above object, in the method for reinforcing a close mountain tunnel according to the present invention, when excavating mountain tunnels composed of adjacent advanced and reverse shafts, reinforcement in the adjacent mountain tunnel for reinforcing the advanced tunnel is provided. In this method, a space is provided with respect to the side wall surface of the pillar part after excavation of the advanced mine, and a plurality of support materials are arranged so as to lean against the side of the tunnel along the tunnel traveling direction, and between adjacent support materials. It is characterized in that a wall body portion is formed by closing with a partition plate, and a solidified body is filled between the wall body portion and the pillar portion side wall surface.

  In the present invention, a support material such as a steel material is leaned on the side wall surface of the pillar portion, and a wall body portion is formed by closing a space between the support materials with a partition plate, and solidified into a space formed on the tunnel wall surface side of this wall body portion. The pillar structure after excavation of the advanced mine can be reinforced by a simple structure of filling the body. This reinforced portion can be formed by connecting a reinforced portion having an appropriate distance in the tunnel traveling direction in front of the existing reinforced portion along with excavation of the advanced mine. Since it is a reinforcement method to install a reinforcement part with a simple structure in this way, the construction period and construction cost are reduced compared to conventional methods for improving the natural ground for the pillar part and increasing the bearing strength of the advanced mine support structure. Can be achieved.

In addition, reinforcement is possible regardless of the state of steel support or sprayed concrete that is constructed immediately after excavation, and the reinforced part that is no longer needed can be removed by removing the support material and partition plate and removing the solidified body. The reinforcing part can be removed easily.
As a result, even if the reverse mine excavates the side of the reinforced portion of the advanced mine, it is possible to suppress an increase in the bending moment of the side wall of the pillar portion where the reinforced portion of the advanced mine is formed. The stability of the natural ground in the pillar part between mountain tunnels can be ensured. It is possible to excavate in the stable ground even in the reverse shaft.

  Moreover, in the reinforcement method in the close mountain tunnel which concerns on this invention, after the solidified body solidifies, it is preferable to excavate the side area | region of the reinforcement part of the advanced mine formed in the tunnel advancing direction with a reverse mine.

  In this case, after the solidified body of the reinforced portion is completely solidified, the side of the reinforced portion is excavated by the reverse shaft, so that the bending moment acting on the side wall of the pillar portion where the reinforced portion of the advanced mine is installed is surely secured. Can be small.

  Further, in the reinforcement method in the close mountain tunnel according to the present invention, the reverse mine lining is preceded by the advanced mine, and after the advance pit lining is completed, the advanced mine reinforcement is removed, It is preferable to construct an advanced mine lining at the removal site.

  According to the reinforcement method in the close mountain tunnel of the present invention, the reverse shaft becomes stable by lining and the generated stress can be suppressed, so that the natural ground in the pillar portion is prevented from becoming unstable by the reverse shaft. can do. Therefore, it becomes possible to remove the reinforcement part of the advanced mine located in the side of the reverse mine which was lined, and can perform lining after that.

  According to the reinforcement method in the close mountain tunnel of the present invention, the pillar portion side wall surface of the advanced mine is reinforced by a reinforcement structure that is easy to install and remove, thereby improving the stability of the pillar portion ground during excavation of the reverse mine. Since it can be secured, it is possible to reduce the construction period and construction cost for reinforcement.

It is a cross-sectional view which shows the reinforcement method in the mountain tunnel by embodiment of this invention. It is a cross-sectional view which shows the structure of the reinforcement part constructed in a 1st tunnel. It is a partially broken perspective view which shows the structure of a reinforcement part. FIG. 4 is a sectional view taken along line AA shown in FIG. 3. (A)-(c) is a figure which shows the construction procedure of a mountain tunnel. It is an analysis result at the time of completion of advanced mine excavation at the time of providing a reinforcement part by an example, (a) is a figure showing an analysis model, and (b) is a figure showing a bending moment. It is an analysis result at the time of completion of advanced mine excavation in the comparative example which does not provide a reinforcement part, (a) is a figure showing an analysis model, and (b) is a figure showing a bending moment. It is an analysis result at the time of completion of reverse mine excavation in the case of providing a reinforcing portion according to the embodiment, (a) is a diagram showing an analysis model, (b) is a diagram showing a bending moment. It is an analysis result at the time of completion of reverse shaft excavation in the comparative example which does not provide a reinforcement part, (a) is a figure showing an analysis model and (b) is a figure showing a bending moment.

  Hereinafter, the reinforcement method in the proximity mountain tunnel by embodiment of this invention is demonstrated based on drawing.

  As shown in FIG. 1, the adjacent mountain tunnel (mountain tunnel 1) according to the present embodiment has a first tunnel 1A (advanced mine) and a second tunnel 1B (reverse mine) spaced apart (pillar part P). It is a tunnel that is excavated in parallel in a close state and applied to, for example, a two-lane road tunnel. Here, the tunnel traveling direction is a direction toward the paper surface in FIG.

In the present embodiment, the first tunnel 1A has a small cross-sectional shape with respect to the second tunnel 1B. In the mountain tunnel 1, the levels in the depth direction of both tunnels 1 </ b> A and 1 </ b> B are different, and the first tunnel 1 </ b> A forming an advanced mine is provided at a position shallower than the second tunnel 1 </ b> B. That is, the second tunnel 1B is located obliquely below and to the right of the first tunnel 1A in the tunnel cross section of FIG.
Here, the first tunnel 1A and the second tunnel 1B are constructed with the same support structure and lining structure. In FIG. 1, the inner line (solid line) of the tunnel excavation line indicates the steel support 10, and the inner line (two-dot chain line) of the steel support 10 indicates the lining 11. In addition, shotcrete is constructed between the steel supporters 10 adjacent to each other in the tunnel traveling direction.

The pillar portion P is a narrow region between the first tunnel 1A and the second tunnel 1B, and is located outside the leg portion 1a continuously provided from the upper half cross section to the invert portion in the first tunnel 1A. In the second tunnel 1B, the second tunnel 1B is located outside the side wall 1b in the middle of the leg from the top end of the upper half cross section. Earth pressure acts on the natural ground of the pillar portion P from above, and earth pressure acts in the direction of pressing the wall surfaces of the first tunnel 1A and the second tunnel 1B.
Here, in the first tunnel 1A, the tunnel wall surface including the leg portion 1a in contact with the pillar portion P is referred to as a “pillar portion side wall surface 1P”, and the tunnel wall surface covered with the reinforcing portion 2 (hatched portion) described later shown in FIG. Say.

As shown in FIG. 2, the first tunnel 1 </ b> A is provided with the reinforcing portion 2 on the face side of the existing reinforcing portion 2 sequentially with respect to the pillar portion side wall surface 1 </ b> P as the dug progresses. It is removed at the timing.
As shown in FIGS. 2 to 4, the reinforcing portion 2 has a predetermined distance from the pillar side wall surface 1P after excavation of the first tunnel 1A, and a steel material 21 (support material made of a plurality of H-shaped steels). ) Obliquely leaning against the tunnel side surface and arranged along the tunnel traveling direction X (see FIG. 3), and the wall portion 20 is formed by closing the space between the adjacent steel materials 21 and 21 with the partition plate 22; It is constructed by filling the fluidized soil 23 (solidified body) between the wall portion 20 and the pillar side wall surface 1P.
In FIG. 4, the steel support 10 is omitted while the fluidized soil 23 is being filled.

  The steel material 21 is provided at the same position and at the same pitch in the tunnel travel direction X as the steel support 10 arranged in the tunnel travel direction X. As shown in FIG. 2, the lower end 21a and the upper end 21b are steel support 10 is locked. The steel material 21 may be simply brought into contact with the steel support 10 by its own weight, or may be fixed by a fixing means such as a bolt or welding.

  The partition plate 22 is made of a thin plate-like member such as a veneer plate or a steel plate having a strength capable of withstanding the filling pressure of the fluidized soil 23, and closes between the steel materials 21 and 21 so as to close the steel material 21 of the H-shaped steel. The inner flange 21c (see FIG. 4) on the inner side of the tunnel is locked inside. Specifically, as shown in FIG. 4, by inserting both ends of the partition plate 22 in the tunnel traveling direction X into a region surrounded by the inner flange 21 c, the outer flange 21 d, and the web 21 e of the steel material 21, The partition plate 22 is pressed toward the tunnel inner space by the filling pressure of the liquefied soil 23, and the end of the partition plate 22 is in contact with the inner flange 21c. The wall part 20 has a function of a mold so as not to flow out.

  In addition, the construction range (position, cross-sectional shape) of the reinforcement part 2 is determined according to the cross-sectional shape of the first tunnel 1A, the separation distance of the pillar part P, and the geological condition of the natural ground.

Next, the construction method of the mountain tunnel 1 using the reinforcement method which installs the reinforcement part 2 in the 1st tunnel 1A is demonstrated based on drawing.
As shown in FIG. 5 (a), the mountain tunnel 1 is excavated with a difference in the respective face positions of the first tunnel 1A serving as an advanced tunnel and the second tunnel 1B serving as a reverse tunnel. In the first tunnel 1A, a reinforcing portion 2 is installed at a location where a steel support 10 (see FIG. 1) is constructed at a predetermined distance from the face. Further, a cover 11 is constructed in the second tunnel 1B so as to overlap in the tunnel traveling direction X on the side of the rear portion of the reinforcing portion 2 in the first tunnel 1A.

As shown in FIG. 5 (b), after excavating the first tunnel 1A by a predetermined distance (symbol L1 in the figure) and constructing a steel support (not shown), the reinforcing portion corresponding to the excavation distance L1 2 (here, the portion 2A) is installed.
Next, the second tunnel 1B is excavated by a predetermined distance (symbol L2 in the figure, here L1 = L2) and a steel support (not shown) is installed. The excavation range of the second tunnel 1B at this time is a region (solidification completion reinforcement portion 2B) in which the fluidized soil 23 (see FIG. 2) of the reinforcement portion 2 in the first tunnel 1A is sufficiently solidified. That is, after the fluidized soil 23 is solidified, the side of the solidification completion reinforcing portion 2B is excavated by the second tunnel 1B. And in the 2nd tunnel 1B, the lining 11A is constructed in the face side of the tunnel advancing direction X with excavation. In addition, the code | symbol 2C of FIG.5 (b) is a reinforcement part removed at the next process, Comprising: It becomes a location located in the side of the location where the lining 11 was already completed in the 2nd tunnel 1B.

Next, as shown in FIG. 5C, in the first tunnel 1 </ b> A, the lining 11 of the second tunnel 1 </ b> B is completed at the rear end side of the reinforcing portion 2 and is placed in a stable state. The reinforcement part of the code | symbol 2C is removed.
In this way, the lining 11 of the second tunnel 1B is constructed ahead of the first tunnel 1A, and after the lining of the second tunnel 1B is completed, the reinforcing portion 2C of the first tunnel 1A is removed, and the reinforcing portion 2C The lining 11 is constructed at the removal site.
In addition, since the steel material 21 can be used again what was removed, the material cost required for reinforcement can be suppressed.

  In the reinforcement method in the mountain tunnel according to the present embodiment, as shown in FIG. 1, the steel material 21 is leaned against the pillar side wall surface 1P, and the steel material 21 is closed with a partition plate 22 to form the wall body portion 20. The pillar portion P after excavation of the first tunnel 1A can be reinforced by a simple structure in which the fluidized soil 23 is filled in the space formed on the tunnel wall surface side of the wall body portion 20. The reinforcement portion 2 can be formed by connecting the reinforcement portion 2 having an appropriate distance in the tunnel traveling direction X to the front of the existing reinforcement portion 2 as the first tunnel 1A is excavated. Since it becomes a reinforcing method to install the reinforcing part 2 having a simple structure as described above, the construction period and the construction cost are reduced as compared with the conventional method of improving the natural ground for the pillar part and increasing the bearing strength of the advanced mine support structure. Reduction can be achieved.

  In addition, reinforcement is possible regardless of the state of steel support work or sprayed concrete that is constructed immediately after excavation, and the reinforced part 2 that is no longer needed is removed from the steel material 21 and the partition plate 22 and fluidized soil. By removing 23, the reinforcing part 2 can be easily removed.

  As a result, even if the second tunnel 1B excavates the side of the reinforcing portion 2 of the first tunnel 1A, the bending moment of the pillar side wall surface 1P on which the reinforcing portion 2 of the first tunnel 1A is formed increases. It can suppress, and the stability of the natural ground of the pillar part P can be ensured. In the second tunnel 1B, excavation is possible with stable ground.

  Further, after the fluidized soil 23 of the reinforcing portion 2 is completely solidified, the side of the reinforcing portion 2 is excavated by the second tunnel 1B, so the side of the pillar portion where the reinforcing portion 2 of the first tunnel 1A is installed The bending moment acting on the wall surface 1P can be reliably reduced.

  Further, since the second tunnel 1B is stabilized by the lining 11 and the generated stress can be suppressed, it is possible to suppress the natural ground of the pillar portion P from being unstable by the second tunnel 1B. Therefore, it becomes possible to remove the reinforcement part 2 of the 1st tunnel 1A located in the side of the 2nd tunnel 1B covered, and can cover it after that.

  As described above, in the reinforcement method in the close mountain tunnel according to the present embodiment, the pillar side wall surface 1P of the first tunnel 1A is reinforced by the reinforcement structure that is easy to install and remove, so that the second tunnel 1B can be Since the stability of the natural ground of the pillar portion P can be ensured, it is possible to reduce the work period and the construction cost for reinforcement.

  Next, examples carried out to support the effect of the reinforcing method in the close mountain tunnel according to the above-described embodiment will be described below.

In this example, the generated stress (cross-sectional force) of the steel support with or without the reinforcing portion 2 of the above-described embodiment was compared by analysis.
The supporting member used in this analysis is a combination of a high standard steel supporting work such as SS540 and HH-200 and a high strength shotcrete with a strength of 36 N / mm ² .

  First, when the first tunnel 1A, which is an advanced mine, is excavated (when the reverse mine does not excavate the side of the excavated advanced mine), the reinforcement portion 2 shown in FIGS. 6A and 6B is provided. When comparing the example with the comparative example in which the reinforcing portion shown in FIGS. 7A and 7B is not provided, there is no difference between the bending moment M1 according to the embodiment of FIG. 6B and the bending moment M2 according to the comparative example. I can confirm that.

On the other hand, in the case where the side of the excavated first tunnel 1A is excavated by the second tunnel 1B, the embodiment provided with the reinforcing portion 2 shown in FIGS. 8A and 8B, and FIG. ) And a comparative example not provided with a reinforcing portion shown in (b). In this case, the bending moment M3 according to the example of FIG. 8B was smaller than the bending moment M4 according to the comparative example, and the incremental stress with respect to the comparative example of the example was about 1 / 2.5. That is, when installing the reinforcement part 2, as shown in FIG.8 (b), the bending moment M3 in the pillar part P is the bending moment M1 which excavated only the advanced mine (1st tunnel 1A) (FIG.6 (b) )) Only slightly, and it can be confirmed that it is smaller than the increase in the bending moment M4 (FIG. 9B) of the comparative example in which the reinforcing portion is not installed.
In addition, since the embodiment having the reinforcing portion 2 is also about half of the comparative example with respect to the increment of the axial force, the generated stress of the support member can be reduced by installing the reinforcing portion 2 according to the present embodiment, It can be confirmed that the construction can be performed by a supporting member equivalent to that of a single (one) mountain tunnel.

As mentioned above, although embodiment of the reinforcement method in a close mountain tunnel by this invention was described, this invention is not limited to said embodiment, It can change suitably in the range which does not deviate from the meaning.
For example, in the present embodiment, an H-section steel material 21 is used as a support material for the reinforcing portion 2, but the material is not limited to this, and a channel material (grooved steel), an angle material (an angle steel). It is also possible to use steel materials such as, or columnar wood. In short, it is only necessary to be able to constitute the wall body portion 20 that can withstand the filling pressure until the solidified body provided between the partition plate 22 and the tunnel wall surface is solidified.

  In the present embodiment, the first tunnel 1A, which is an advanced mine, is an example having a smaller cross-sectional shape than the second tunnel 1B, which is a reverse mine. Can be set as appropriate. That is, the first tunnel 1A may have a larger cross section than the second tunnel 1B, or both the tunnels 1A and 1B may have the same cross section. In the present embodiment, the first tunnel 1A is shallower than the second tunnel 1B. However, the present invention is not limited to this, and the second tunnel 1B may be shallower than the first tunnel 1A. Further, the tunnels 1A and 1B may be tunnels constructed at the same depth level.

  In addition, it is possible to appropriately replace the constituent elements in the above-described embodiments with well-known constituent elements without departing from the spirit of the present invention, and the above-described embodiments may be appropriately combined.

1 Mountain tunnel (proximity mountain tunnel)
1A 1st tunnel (advanced mine)
1B Second tunnel (backward mine)
1P Pillar part side wall surface 2 Reinforcement part 10 Steel support 11 Covering 20 Wall part 21 Steel material (support material)
22 Partition plate 23 Fluidized soil (solidified body)
P Pillar part X Tunnel traveling direction

Claims (3)

When excavating mountain tunnels composed of adjacent advanced pits and reverse pits, a reinforcement method in the adjacent mountain tunnel for reinforcing the advanced mine tunnels,
A space is provided for the side wall surface of the pillar portion after excavation of the advanced mine, and a plurality of support materials are arranged against the tunnel side surface along the tunnel traveling direction.
Reinforcing in a close mountain tunnel, wherein a wall portion is formed by closing a space between adjacent support members with a partition plate, and a solidified body is filled between the wall portion and the side wall surface of the pillar portion. Method.   The method for reinforcing a close mountain tunnel according to claim 1, wherein after the solidified body is solidified, a lateral region of the reinforcing portion of the advanced mine formed in the tunnel traveling direction is excavated by a reverse shaft. We constructed the lining of the reverse mine ahead of the advanced mine, and then removed the reinforcement part of the advanced mine after the lining of the forward mine was completed.
The method for reinforcing a close mountain tunnel according to claim 1 or 2, wherein a lining of an advanced mine is constructed at a location where the reinforcing portion is removed.

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