JPS63201295A - Method of protective construction of existing tunnel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention provides a method for reinforcing existing tunnels from the outside without hindering the use of the tunnels, as underground tunnels in urban areas become obsolete. Concerning protective construction methods.

(Prior art) As underground tunnels age, the simplest construction method is shown in Figure 8, in order to use the tunnels as they are without destroying them, and to carry out reinforcement work on the tunnels. First, both sides of the existing tunnel 1 are surrounded by underground continuous walls 2, and in this state, the upper part of the existing tunnel 1 is excavated, a concrete top plate 3 is erected, and the existing tunnel 1 is surrounded.

(Problem to be solved by the invention) However, in order to carry out this construction in urban areas, etc., it is necessary to consider the relationship between the above-ground part and existing buildings, the gas pipes placed underground above the existing tunnel 1, etc. Various underground structures such as water and sewage pipes and telephone cable pipes must be considered. Particularly in subway tunnels, which are aging rapidly in downtown areas, the buried objects above them are arranged in a complicated manner, making it difficult to know where they are located, and in some cases, existing buildings are located on the ground surface above the tunnel. ,therefore,
Practically speaking, this type of construction method has a very limited range of application.

In addition, if the existing tunnel 1 is to be demolished and a new tunnel constructed instead of this type of protection work, an alternative site must be secured in advance to detour the commercial track, so there is not enough room for an alternative site. Without it, the rebuilding work would not be possible.

This invention was made in view of the above-mentioned circumstances, and its purpose is to develop a method for constructing a protective structure without destroying the existing tunnel and without requiring much ground surface area. It is about providing.

(Means for Solving the Problems) In order to achieve the above-mentioned object, this invention excavates at least one starting shaft in the upper side of an existing tunnel, and from this starting shaft along the longitudinal direction of the existing tunnel. Hollow boxes are successively arranged in close parallel on the top plate, concrete is placed inside these hollow boxes to construct a protective plate, and a pair of guide lines are installed from the oscillation shaft to both sides of the existing tunnel. The present invention is characterized in that a pit is excavated, concrete is poured into the shaft, and protective walls are constructed outside both sides of the existing tunnel.

(Function) In the above protection method, if you select a small area of land that will not be affected by existing buildings or buried objects within the section to be protected and excavate a starting shaft there, the existing buried structures above the tunnel will be removed. It is possible to propel a hollow box or excavate a shaft along both sides of an existing tunnel without being affected or interfered with by the tunnel.

(Example) Hereinafter, an example of the present invention will be described in detail using the drawings.

1 to 7 show an embodiment of the existing tunnel protection method according to the present invention.

In the figure, reference numeral 10 indicates a dilapidated existing tunnel in an urban area, and in the embodiment, a case where a predetermined section on the outer periphery of this existing tunnel 10 is to be protected is illustrated.

First, as shown in FIG. 4, temporary reinforcement works 129 are installed inside the existing tunnel 10 as needed.
Underground reinforcement work such as creating foundation piles 16 and constructing intermediate columns 18 is performed.

Next, as shown in FIGS. 1 and 2, a starting shaft 20 longer than the width of the existing tunnel 10 is excavated on the top plate 10a of the existing tunnel 10 so as to be orthogonal to the longitudinal direction of the tunnel 10.

The starting shaft 20 is selected at a location where it will not be affected by buildings on the ground or buried underground, and is formed into a rectangular shape by earth retaining piles 22, sheet piles 24, and raised sides 26, as shown in detail in FIGS. 6 and 7. The excavation depth is continued until the top plate 10a of the existing tunnel 10 is reached.

When the starting shaft 20 is constructed, the top plate 1 of the existing tunnel 10 is moved along the longitudinal direction of the existing tunnel 10 starting from the starting shaft 20.
The hollow box 28 is placed on 0a by the propulsion method.

Prior to propulsion of the hollow box 28, a reaction force receiving wall 30 is formed along one longitudinal side of the starting shaft 20, and a pair of rails 32, 32 are laid on the other side. be done.

On the rail 32, there is a carriage 34 for transporting the hollow box 28, and the hollow box 28 carried by the carriage 34 is received.
a pedestal 36 for positioning this on one side of the starting shaft 20;
A cart 40 carrying an interpolation ring 38 is installed.

Further, a propulsion jack 44 is installed on the pedestal 36 to abut against the reaction force receiving wall 30 via the reaction force receiving steel 1/A42 and to propel the hollow box 28. A push ring 46 is attached to the telescopic plunger side of 44.

When the preparation work for propulsion as described above is completed, first, the pedestal 36 on which the propulsion jack 44 is mounted is set at one end of the protection work constructed above the existing tunnel 10.

Next, the hollow box 28 is placed on the transportation trolley 34 and the frame 3 is moved.
After traveling to the vicinity of 6, the hollow box 28 is transferred to the stand 36 and set so that the negative end is in contact with the side wall of the starting shaft 20.

In this case, a blade opening 48 is provided at the tip of the first stage hollow box 28.
is installed.

Next, the propulsion jack 44 is extended to press the rear end of the hollow box 28, and the hollow box 28 is press-fitted so as to be parallel to the top plate 10a of the existing tunnel 10.

During press-fitting, if the jack stroke of the propulsion jack 44 is short, the interposition ring 38 is inserted between the push ring 46 and the hollow box 28.

Further, at the same time as the hollow box 28 is press-fitted, the earth and sand inside the hollow box 28 is excavated, and the excavated earth and sand is discharged to the outside of the starting shaft 20 using a belt conveyor or the like.

When the first stage hollow box 28 is press-fitted to a predetermined position,
During that time, the second stage hollow box 2 was transported by the transport trolley 34.
8 is transferred onto the pedestal 36, the boxes 28 and 28 are joined together with a collar, and the propelling jack 44 press-fits and excavates the inside.

By repeating the above operations, the first stage hollow box 6
When the tip of the 0 reaches a predetermined position on the Suzaka 10a, the propulsion work of the first row ends.

When the installation of the hollow boxes 28 for one row is completed, the pedestal 36 is moved by a distance approximately equivalent to the width of the hollow boxes 28, and the same operation as above is repeated to install the hollow boxes 28 in the second and subsequent rows. Installation of the body 28 takes place.

Here, the hollow boxes 28 used in this embodiment will be explained. Two types of hollow boxes 28 each having a rectangular cross section are used.

One type of hollow box 28a is a rectangular steel tube with both ends open and steel plates fixed to four sides, and is used for the first and last rows of protective plates. Another type of hollow box 28b is used for each row in the middle section, and its details are shown in FIG.

The hollow box 28b has a top plate 281 and a bottom plate 282 made of steel plates similar to those described above, but has a U-shaped cross section with an open side, and the other side is made of a wire mesh plate 283 such as a lath. . In addition, the upper and lower sides of both sides are reinforced with angle plates 284, and hook-shaped hook parts 285 in opposite directions are integrated into the side surfaces of each angle plate 284, so that each of the adjacent rows has a The hollow boxes 28b are connected to each other in a piece-like manner, so that the hollow boxes 28b in adjacent rows can be closely arranged in a connected state.

Note that caulking material 49 is placed inside the engaging surface of the hook portion 285.
By filling the hollow boxes 28b with each other, the joint surfaces of the hollow boxes 28b are completely sealed and a watertight state can be maintained.

Further, since the connection is weak only by engagement of the hook portion 285, the hollow boxes 28 of the front and rear stages are
If the angle plates 284 (b) are connected to each other by bolts B, the hollow boxes 28b are connected vertically and horizontally, resulting in a strong connection.

Furthermore, it is of course possible to connect the hollow boxes 28a of the first or last row to the hollow boxes 28b using the hook portions 285 and the bolts B.

Now, by repeating the above steps and arranging the hollow boxes 28 throughout the protection area, adjacent rows will be joined in a vertical and horizontal matrix shape with horizontal communication through the wire mesh plates 283, and one flat space will be formed. The protective plate 50 is constructed by enclosing each hollow box 28, arranging reinforcing bars vertically and horizontally inside the box, and pouring concrete.

On the other hand, both end portions of the starting shaft 20 that protrude outward beyond the width of the existing tunnel 10 are removed from the side wall 10b of the existing tunnel 10 before concrete is poured to form the protective plate 50.
After excavating to a depth that corresponds to the lower end of the tunnel, a pair of lower guide shafts 52 are excavated by the tunneling method (hand digging or machine digging) in the area where the protective wall is to be constructed (see Figure 5). .

The cross-sectional shape of the lower shaft 52 is rectangular in this embodiment, and shoring structures 54 made of H-beams are arranged at appropriate intervals along the excavation direction, and the excavation wall surface is lined with sprayed concrete. has been done.

Once the lower guide shaft 52 is formed in a predetermined range, reinforcing piles 56 are constructed below the guide shaft 52 at appropriate intervals along the excavation direction using the cast-in-place pile construction method, thereby increasing the vertical bearing capacity of the protective wall and Reinforce horizontal support for lateral earth pressure.

Next, inside the lower shaft 52, the shape of the protection plate 50 is set at a distance from the side wall 10b of the existing tunnel 10.
The lower protective wall 58, which has a wall thickness that is driven by a cross-sectional force generated by a load, is formed by installing a frame (not shown) along the guide shaft 52 and pouring concrete.

Then, when the lower stage protection II wall 58 is constructed, the formwork is removed and a filler material 60 such as aerated concrete is injected and filled between the protection wall 58 and the guide shaft 52.

Next, an upper guide shaft 62 is excavated above the lower guide shaft 52.

The upper shaft 62 has almost the same cross-sectional shape as the lower shaft 52 and is constructed by appropriately arranging the supports 54.
When the construction of the protective plate 50 is completed, concrete is poured into the hollow box 28 to construct the protective plate 50 (see FIG. 6).

When the protective plate 50 is formed, the protective plate 5 is placed inside the upper guide shaft 62.
0 and the lower protection wall 58 is formed.

Thereafter, the portions of the upper guide shaft 62 other than the upper protection wall 64 are filled with the filler 60 to complete the protection work.

In the above embodiment, the starting shaft 20 was provided only at one end of the protective plate 50 formed above the existing tunnel 10, but a plurality of starting shafts 20 may be provided at both ends of the protective plate 52 forming the starting shaft 20. .

Further, in this embodiment, the guide shafts 52 and 62 formed on both sides of the existing tunnel 10 are formed in two layers, but they may be formed in one layer in consideration of the height of the existing tunnel 10 and workability. However, there may be more.

Furthermore, the hollow box 28 having an opening-shaped cross section as shown in the above embodiment
The opening on one side of b may be made of a removable steel plate and removed after installation.

Furthermore, the other wire mesh plate 28c may be a perforated plate with holes bored at appropriate locations, and the protective wall 58.
64 can also be constructed by arranging reinforcement inside each shaft 52, 62 and pouring concrete, thereby making the entire new area a protective wall.

(Effects) As explained in detail using the embodiments above, in the existing tunnel protection method of the present invention, at least the part exposed to the ground surface is only one starting shaft, and most of the other parts are exposed to the ground surface. Since the work is underground, the ground surface area required for construction can be kept to a minimum, and work can proceed without interference from underground objects above the existing tunnel or the foundations of existing buildings. .

Therefore, the construction method of this invention is particularly suitable for the protection and reinforcement work of dilapidated tunnels in urban areas, and can be performed at minimum construction cost.

[Brief explanation of the drawing]

Figure 1 is a plan view showing the construction method of this invention, Figure 2 is a sectional view taken along line A-A in Figure 1, Figure 3 is a detailed view of the hollow box, and Figures 4 to 7 are the construction order of the protective wall. FIG. 8 is a vertical cross-sectional view showing a case where an existing tunnel is protected by a general underground continuous wall construction method. 10... Existing tunnel 20... Starting shaft 28...
・Hollow box 50... Protective plate 58... Lower protective wall 64... Upper protective wall Patent applicant Obayashi Corporation Agent Patent attorney - Ken Iro Axial Patent attorney Masatoshi Matsumoto Figure 4 Figure 5 Figure 6 Figure 7

Claims (2)

[Claims] (1) At least one starting shaft is excavated on the upper side of the existing tunnel, and hollow boxes are successively arranged closely in parallel on the top plate of the existing tunnel from the starting shaft along the longitudinal direction of the existing tunnel. Concrete is poured inside the hollow box to construct a protective plate, and a pair of guide shafts are excavated from the oscillation shaft to both sides of the existing tunnel, and concrete is poured inside the guide shafts. A method for protecting an existing tunnel, characterized by constructing protective walls on the outside of both sides of the existing tunnel. (2) The method for protecting an existing tunnel according to claim 1, characterized in that reinforcing piles are sequentially constructed below the guide shaft by a cast-in-place pile method.