JP6874375B2 - How to build a tunnel skeleton - Google Patents

Description

The present invention relates to a method for constructing a tunnel skeleton in which a planned tunnel construction area is surrounded by a plurality of outer shell tunnels and a tunnel skeleton is constructed by utilizing the inner space of the outer shell tunnel.

Conventionally, as a method of constructing a lining body of a large-section tunnel in the ground, for example, in Patent Document 1, a plurality of roof shield tunnels are constructed so as to surround a planned construction area of an underground cavity, and a segment of the roof shield tunnel is constructed. Will be partially removed and the ground outside it will be excavated to provide a space between the roof shields that communicates with the roof shield tunnel. After that, concrete is filled in this space and the roof shield to construct a series of lining concrete. Then, in order to ensure the waterproof performance of these lining concretes, a tarpaulin is installed on the outer peripheral side of the concrete in a range where it comes into contact with the ground, and both edges of the tarpaulin are opened by removing segments in the roof shield tunnel. It is connected to the peripheral part of the part.

On the other hand, in Patent Document 2, as in Patent Document 1, after providing a space communicating with the roof shield tunnel between the roof shield tunnels, a stiffener is assembled and reinforcing bars and reinforcing bars in the space and the inner space of the roof shield tunnel. Install the formwork. Then, lining concrete is cast and filled inside the formwork, and a lining body is constructed in which adjacent roof shield tunnels are connected to each other. This lining body is formed while being connected to each other between all roof shield tunnels to construct a series of main lining walls with a ring-shaped cross section. In a main lining wall using such a formwork, it is common to adopt a method of ensuring waterproof performance by laying a waterproof sheet on the entire outer surface side thereof.

Japanese Unexamined Patent Publication No. 2009-174169 Japanese Patent No. 4958035

However, in either of the methods of Patent Document 1 and Patent Document 2, when the lining body of the large cross-section tunnel is constructed of reinforced concrete, the reinforcing bars to be adopted have a large diameter and are heavy, so that the reinforcing bars can be arranged. It tends to be complicated. In addition, since the space is limited in the narrow roof shield tunnel, the workability is inferior. Therefore, not only the reinforcement work but also the work related to the installation of formwork and the placement of concrete, etc., requires a great deal of labor and time. Needs.

Further, in the method using a formwork as in Patent Document 2, a stiffener for stiffening the roof shield with a part of the segment removed is installed so as to extend substantially in the radial direction when viewed from the cross section of the underground cavity. In addition, formwork arranged so as to connect adjacent roof shields is installed so as to extend in the circumferential direction of the underground cavity. As a result, the stiffener and the formwork interfere with each other, and it becomes necessary to make a hole in the formwork and allow the stiffener to penetrate the formwork. For this reason, the part where the connection is settled tends to become a water path, which causes a problem in water stopping performance.

The present invention has been made in view of the above problems, and a main object thereof is to provide a method for constructing a tunnel skeleton which is a tunnel lining body and has high work efficiency while ensuring high water stopping performance. Is.

In order to achieve such an object, in the method for constructing a tunnel skeleton of the present invention, the planned construction area of the tunnel is surrounded by a plurality of outer shell tunnels arranged in parallel, and the tunnel skeleton is constructed by utilizing the inner space of the outer shell tunnel. It is a method of constructing a tunnel skeleton to be constructed, in which a plurality of support works are installed in the inner space of the outer shell tunnel at intervals in the axial direction of the outer shell tunnel, and the adjacent outer shell tunnels face each other. The first step of removing a part of the segment to provide a communication space for mutual communication, and the steel shell division installation area for installing the steel shell divisions constituting the tunnel skeleton across the communication space. A second step of securing by removing a part of the support work, and an opening reinforcing column capable of stiffening the outer shell tunnel while sandwiching the steel shell divided body in the steel shell divided body installation area. using a third step of placing the steel shell split body, a plurality of the steel shell divided body which is connected, e Bei a fourth step of filling the filling concrete, the said opening reinforcing pillars It is composed of an inner column and an outer column provided coaxially and an intermediate column provided between the two, and the intermediate column is arranged in a hollow portion of the steel shell split body .

Further, in the method for constructing a tunnel skeleton of the present invention, before the fourth step, the second step and the third step are sequentially repeated in the axial direction of the outer shell tunnel, and the steel straddling the communication space. The shell divided bodies are sequentially connected in the axial direction of the outer shell tunnel.

Further, the method for constructing a tunnel skeleton of the present invention is characterized in that the first step to the fourth step are carried out for each pair of adjacent outer shell tunnels.

In addition, in the method for constructing a tunnel skeleton of the present invention, the planned construction area of the tunnel is divided into a plurality of sections in the axial direction, and the first step to the fourth step are carried out for each section. It is a feature.

According to the method for constructing a tunnel skeleton of the present invention, a steel shell split body is installed in the inner space of a plurality of outer shell tunnels surrounding a planned tunnel construction area, and the steel shell split body is filled with filled concrete. It is constructed by the so-called SC structure. As a result, the labor required for formwork and rebar work can be greatly reduced, so that the workability can be improved and the construction time can be significantly shortened even in the inner space of a narrow outer shell tunnel. It becomes possible to do.

Further, the steel shell split body is installed in the inner space of the outer shell tunnel by using an opening reinforcing column capable of stiffening the outer shell tunnel while sandwiching the steel shell split body. As a result, the steel shell split body can be installed in the inner space of the outer shell tunnel while the outer shell tunnel is stiffened by the opening reinforcing column without providing a through hole in the steel shell split body. Therefore, it is possible to prevent water from leaking into the inner space of the tunnel skeleton without creating a gap that becomes a water path at a portion of the steel shell split body where the opening reinforcing columns interfere with each other.

Further, since the water blocking material is provided on the side peripheral surface of the steel shell divided body, the water blocking material is arranged at the joint portion formed by connecting the plurality of steel shell divided bodies. Therefore, even when spring water is generated from the ground located on the outer peripheral side of the tunnel skeleton, the gap between the joints is not sealed by the water blocking material and a water path is not formed, so that the tunnel skeleton has a higher stoppage. It becomes possible to secure water-based properties.

In the method of constructing the tunnel skeleton of the present invention, in the first step, a new support is additionally installed between the adjacent support in each of the outer shell tunnels after the communication space is provided. It is a feature.

According to the method for constructing the tunnel skeleton of the present invention, since a plurality of new support works are additionally installed in the inner space of the outer shell tunnel, the load load on one support work can be reduced. It is possible to carry out the work safely even if a part of the support work is removed in order to secure the above.

According to the present invention, since the tunnel skeleton is constructed by filling a plurality of connected steel shell divided bodies with filled concrete, the work efficiency can be significantly improved and the steel shell divided bodies have gaps that serve as water paths. It does not exist, and it is possible to ensure high water stopping performance in the tunnel frame.

It is a figure which shows the outline of the large cross-section tunnel of this invention. It is a figure which shows the cross section of the large section tunnel construction plan area of this invention. It is a figure which shows the detail of the tunnel skeleton of this invention. It is a figure which shows the detail of the steel shell split body of this invention. It is a figure which shows the flow of the construction method of the tunnel skeleton of this invention. It is a figure which shows the section at the time of constructing the tunnel skeleton of this invention. It is a figure which shows the construction method of the tunnel skeleton of this invention (the 1). It is a figure which shows the construction method of the tunnel skeleton of this invention (the 2). It is a figure which shows the construction method of the tunnel skeleton of this invention (the 3). It is a figure which shows the construction method of the tunnel skeleton of this invention (the 4).

The present invention relates to a method for constructing a tunnel skeleton for constructing a tunnel skeleton by surrounding a planned tunnel construction area with a plurality of outer shell tunnels arranged in parallel and using the inner space of these outer shell tunnels. is there. In the present embodiment, as an example of a tunnel to be constructed, a large-section tunnel constructed in a part of the main line shield tunnel is taken as an example, and a method of constructing a tunnel skeleton as a main lining body of the large-section tunnel is shown in the figure below. 1 to FIG. 10 will be described.

As shown in the schematic view of FIG. 1, the large cross-section tunnel 3 is constructed to provide a branching / merging portion with the branch line tunnel 2 in the main line shield tunnel 1, and has a substantially cylindrical cross section having a circular shape. Will be built. The shape of the large cross-section tunnel 3 is not necessarily limited to this, and the cross-section may be an elliptical shape, a rectangular tubular shape, or a frustum-shaped one.

In constructing the large-section tunnel 3, first, as shown in the cross-sectional view of FIG. 2 (a), the periphery of the large-section tunnel construction planned area 4 is surrounded by a plurality of outer shell tunnels 5 arranged in parallel. The outer shell tunnel 5 may be a tunnel constructed by any construction method such as a shield method or a propulsion method, but in the present embodiment, the shield tunnel is adopted.

Next, as shown in FIG. 2B, a tunnel skeleton 9 surrounding the large cross-section tunnel construction planned area 4 is constructed by utilizing the inner sky of the outer shell tunnel 5. The tunnel skeleton 9 is constructed by connecting a plurality of skeleton divided bodies 6 having a rectangular shape in a plan view in the length direction and further connecting a plurality in the width direction as shown in the side view of FIG.

The skeleton split body 6 is arranged so that the length direction coincides with the circumferential direction of the tunnel skeleton 9 and the width direction coincides with the axial direction of the tunnel skeleton 9, and is a so-called half precast member. 7 and the filled concrete 8 filled in the hollow portion of the steel shell split body 7.

As shown in FIG. 4, the steel shell split body 7 includes a curved plate-shaped inner steel shell plate 71 forming the inner peripheral surface of the tunnel skeleton 9, and a curved plate-shaped outer steel shell forming the outer peripheral surface of the tunnel skeleton 9. A plate 72 and a shear reinforcing bar 73 are provided. As shown in FIG. 4A, a plurality of these are connected so that the convex surface of the inner steel shell plate 71 and the concave surface of the outer steel shell plate 72 are opposed to each other at intervals to form a hollow portion. The shear reinforcing bar 73 of the above is arranged and assembled.

As shown in FIG. 4B, the inner steel shell plate 71 has a skin plate 711 made of a rectangular steel plate formed in an arc shape whose length direction forms the inner peripheral surface of the tunnel skeleton 9, and the width of the skin plate 711. A pair of main girders 712 installed at both ends in the direction, a pair of joint plates 713 installed at each end of the skin plate 711 in the length direction, and a skin plate 711 so as to connect the main girders 712 to each other. It comprises a plurality of vertical ribs 714 installed above.

The main girder 712, the joint plate 713, and the vertical rib 714 are all made of rectangular steel plates and are installed so that the surfaces of the main girder 712 and the vertical ribs 714 are orthogonal to each other. They are installed so that they are orthogonal to each other. Further, all of the main girder 712, the joint plate 713 and the vertical rib 714 are installed on the convex surface side of the skin plate 711.

On the other hand, as shown in FIG. 4C, the outer steel shell plate 72 also includes a skin plate 721, a pair of main girders 722, a pair of joint plates 723, and a vertical rib 724, similarly to the inner steel shell plate 71. The skin plate 721 is formed in an arc shape in which the length direction of the rectangular steel plate forms the outer peripheral surface of the tunnel skeleton 9. Further, the main girder 722, the joint plate 723 and the vertical rib 724 are all installed on the concave side of the skin plate 721.

The skeleton split body 6 is formed by connecting one or a plurality of such steel shell split bodies 7 and filling the inside thereof with the filled concrete 8. When a plurality of steel shell split bodies 7 are connected, the steel shell split body 7 has a main girder 712 of the inner steel shell plate 71 and a joint plate 713, and a side peripheral surface of the main girder 722 and the joint plate 723 of the outer steel shell plate 72. Since they are formed, the side peripheral surfaces are brought into contact with each other to be connected.

Specifically, when the joint plates 713 of the inner steel shell plates 71 and the joint plates 723 of the outer steel shell plates 72 in the adjacent steel shell divided bodies 7 are brought into contact with each other and connected, a ring shape is formed. Further, when the main girders 712 of the inner steel shell plate 71 and the main girders 722 of the outer steel shell plate 72 are brought into contact with each other and connected to each other, a tubular shape is formed.

Therefore, as shown in FIGS. 4 (b) and 4 (c), the joint plates 713, 723 and the main girders 712 and 722 of the inner steel shell plate 71 and the outer steel shell plate 72, respectively, are connected members (not shown). A plurality of through holes 715 and 725 are provided to penetrate the through holes. As the connecting member, any high-strength bolt or the like may be adopted as long as it is a member capable of connecting the steel shell divided bodies 7.

Further, as shown in FIG. 4C, two water blocking materials 10 are provided on the joint plate 723 and the main girder 722 of the outer steel shell plate 72 forming the side peripheral surface so as to sandwich the plurality of through holes 725. is set up. In the present embodiment, the water-stopping material 10 is made of water-swellable synthetic rubber, but any material may be used as long as the water-stopping material can be ensured.

As a result, as shown in FIG. 4A, the water blocking material 10 is located at the joint portion 74 on the outer steel shell plate 72 side formed by connecting the plurality of steel shell divided bodies 7. Become. Therefore, when water flows into the joint portion 74 from the outer steel shell plate 72 side, the water blocking material 10 swells and closes the gap of the joint portion 74.

Therefore, the tunnel skeleton 9 constructed by connecting the skeleton split bodies 6 constructed by connecting a plurality of steel shell split bodies 7 is in the inner sky even when there is spring water in the ground on the outer peripheral side thereof. The structure has a high water-stopping property without forming a water path toward the water and causing water leakage. The water blocking material 10 may not be provided on the steel shell split body 7, and the joint portion 74 formed by connecting the plurality of steel shell split bodies 7 may be welded and sealed to ensure water stoppage. ..

By excavating the inside of the tunnel skeleton 9 having such a high water-stopping property, the large-section tunnel 3 is constructed in the large-section tunnel construction planned area 4. The water blocking material 10 provided on the joint plate 723 and the main girder 722 of the outer steel shell plate 72 is provided not only on the outer steel shell plate 72 but also on the joint plate 713 and the main girder 712 of the inner steel shell plate 71. May be good.

The details of the method of constructing the tunnel skeleton 9 using the skeleton split body 6 described above will be described below with reference to the flow chart shown in FIG.

<Pretreatment process>
Prior to constructing the tunnel skeleton 9, a ground improvement part 15 by a freezing method or a chemical injection method as shown in FIG. 7A was constructed on the ground around the plurality of outer shell tunnels 5 to prevent water stoppage. To give. Further, in the present embodiment, as shown in FIG. 6, the planned large-section tunnel construction area 4 is divided into a plurality of sections A, B, ... In the axial direction, and the outer shell tunnels 5 adjacent to each other are divided into each section. The skeleton split body 6 to be connected is constructed.

<First step: STEP1 to 3>
A part of the opposing segments 51 of each of the adjacent outer shell tunnels 5 after installing a plurality of support works 11 in the inner space of each of the adjacent outer shell tunnels 5 at intervals in the axial direction of the outer shell tunnel 5. Is removed to make a cut, and a communication space 12 that communicates with each other is provided.

First, as shown in FIG. 7A, the advance support 111 is installed at an appropriate position in the inner sky of each of the pair of adjacent outer shell tunnels 5. The pre-attached support 111 is one of the support 11 capable of maintaining the inner space cross section even when a part of the outer shell tunnel 5 is cut open, and as shown in FIG. 7 (b). , A plurality of outer shell tunnels 5 are installed at intervals in the axial direction in the section A. (STEP1)

In the present embodiment, not only the advance support 111 but also the additional support 112 described later is installed as the support 11, and the workability of the opening work of the outer shell tunnel 5 is taken into consideration, and the advance support is provided. The arrangement interval of the work 111 is set to the longest interval among the intervals that can hold the inner space cross section when a part of the outer shell tunnel 5 is cut open. However, the installation interval is not necessarily limited to this, and the arrangement interval may be appropriately shortened if necessary.

Further, the pre-attached support 111 may be installed in direct contact with the inner wall surface of the outer shell tunnel 5, but as shown in FIG. 7A, the pre-attached support on the inner wall surface of the outer shell tunnel 5 may be installed. A long pedestal 13 extending in the axial direction of the outer shell tunnel 5 may be installed in advance at the planned installation position of the work 111. In this way, when the support 11 is installed via the long frame 13, the support 11 can be arranged at a desired position without considering the joint position of the segment 51 of the outer shell tunnel 5, so that workability is improved. It can be greatly improved.

Next, as shown in FIG. 7 (c), in the section A, in each of the pair of adjacent outer shell tunnels 5, an excavation work is performed to remove a part of the opposing segments 51, and the ground located between the two. Excavate and remove soil. Further, a water blocking plate 121 is installed so as to bridge the ends of the segments 51 of the adjacent outer shell tunnels 5 exposed by the cutting work, and as shown in FIG. 8A, a pair of adjacent outer shells are provided. A connected space 12 that communicates with the tunnel 5 is constructed. (STEP2)

By covering the ground seen from between the adjacent outer shell tunnels 5 using the water stop plate 121, water leakage from the ground to the communication space 12 is suppressed. After constructing such a communication space 12 so as to be continuous with the entire length of the section A, as a preparatory work for securing the steel shell split body installation area W to be described later, as shown in FIG. An additional support 112 is installed between the attached support 111 via a long stand 13, and the support 11 is added. (STEP3).

<Second step: STEP4>
A part of the support work 11 is removed to secure a steel shell split body installation area W for installing the steel shell split body 7 in a region straddling the inner space of the outer shell tunnel 5 and the communication space 12.

As shown in FIG. 9A, the steel shell split body installation area W is an operation for installing the steel shell split body 7 across the communication space 12 so as to connect a pair of adjacent outer shell tunnels 5. The area. In the present embodiment, the steel shell split body 7 can be installed by removing any one of the pre-attached support work 111 and the additional support work 112 among the support works 11. The length in the width direction (the length in the axial direction of the tunnel skeleton 9) is set to 1/2 of the distance between the pre-supported timbers 111 adjacent to each other in the axial direction of the outer shell tunnel 5.

Therefore, in each of the pair of adjacent outer shell tunnels 5, either the pre-attached support 111 or the additional support 112 of the support 11 is removed to secure the steel shell split body installation area W. (STEP4)

By additionally installing the additional support 112 as the support 11, the load load on one support 11 is reduced. Therefore, in order to secure the steel shell split body installation area W, one of the support 11 Even if the part is removed, the work can be carried out safely.

<Third step: STEP5-6>
The steel shell split body 7 is transported to the steel shell split body installation area W, and the steel shell split body 7 is installed in the outer shell tunnel 5 via the opening reinforcing column 14.

As shown in FIG. 9B, one of a pair of adjacent outer shell tunnels 5 is used as a material transport passage, and the inner steel shell plate 71, the outer steel shell plate 72, and the outer steel shell plate 72 constituting the steel shell split body 7 are formed. The shear reinforcing bar 73 is separately transported and assembled into the steel shell split body 7 in the steel shell split body installation region W as shown in FIG. 9 (c). (STEP5)

In the steel shell split body 7, the main girders 712 and 722 provided on the inner steel shell plate 71 and the outer steel shell plate 72 respectively function as main bars, and the vertical ribs 714 and 724 function as force distribution bars. As a result, since only the shear reinforcing bar 73 is required for the bar arrangement work, it is not necessary to perform complicated bar arrangement work when assembling the steel shell split body 7, and the installation work can be significantly reduced. Become.

In the present embodiment, as shown in FIGS. 4 (b) and 4 (c), the middle main girders 712'and 722' are additionally installed on the inner steel shell plate 71 and the outer steel shell plate 72. The number of the middle main girders 712'and 722' to be additionally installed may be appropriately increased or decreased according to the proof stress required for the steel shell split body 7.

When the assembled steel shell split body 7 is installed in the outer shell tunnel 5, an opening reinforcing column 14 is adopted also as a stiffening of the outer shell tunnel 5 which is partially cut open. As shown in FIG. 10A, the opening reinforcing column 14 is located between the inner column 141 arranged between the inner steel shell plate 71 and the outer shell tunnel 5, and between the outer steel shell plate 72 and the outer shell tunnel 5. It is provided with three members of an outer column 142 arranged in, and an intermediate column 143 arranged between the inner steel shell plate 71 and the outer steel shell plate 72, respectively.

These three members are arranged so as to be coaxial, and are installed at the installation position of the support work 11 removed in the first step. That is, while the intermediate column 143 functions as a means for holding the hollow portion of the steel shell split body 7, the inner steel shell plate 71 is sandwiched between the intermediate column 143 and one end of the inner column 141, and the intermediate column 143 and the intermediate column 143 The outer steel shell plate 72 is sandwiched by one end of the outer column 142. In this embodiment, the outer shell tunnel 5 is pressed at the other end of the inner pillar 141 and the other end of the outer pillar 142, respectively.

As a result, the steel shell split body 7 is installed in the outer shell tunnel 5 via the opening reinforcing column 14, and the opening reinforcing column 14 is a stiffener of the outer shell tunnel 5 in which a part of the segment is removed and cut open. Also works as. The opening reinforcing column 14 is not necessarily limited to the above configuration. For example, an interval holding material for maintaining the interval between the inner steel shell plate 71 and the outer steel shell plate 72 may be diverted to the intermediate column 143 of the opening reinforcing columns 14.

In this way, the steel shell split body 7 is supported by the outer shell tunnel 5 in a state where the outer shell tunnel 5 is sandwiched by the stiffening opening reinforcing columns 14. Therefore, it is not necessary to provide a hole for penetrating the support in the steel shell split body 7, and the tunnel skeleton 3 using the steel shell split body 7 maintains high water stopping performance without forming a water path. Is possible (STEP 6).

In the present embodiment, as shown in FIGS. 9A and 9B, the steel shell divided body 7 is placed 2 in the length direction (circumferential direction of the tunnel skeleton 9) with respect to the steel shell divided body installation area W. The body is installed, but the number may be one or two or more. When a plurality of steel shell split bodies 7 are installed, the joint plates 713 of the inner steel shell plate 71 and the joint plates 723 of the outer steel shell plate 72 are brought into contact with each other and connected via a fastening member.

Further, the length of the steel shell split body 7 in the width direction does not necessarily have to be 1/2 of the distance between the advance support works 111 adjacent to each other in the axial direction of the outer shell tunnel 5. For example, the length may be shorter than the above length, and a plurality of bodies may be connected in the axial direction of the outer shell tunnel 5 in the steel shell split body installation area W. In this case, the main girders 712 of the inner steel shell plate 71 and the main girders 722 of the outer steel shell plate 72 are brought into contact with each other and connected via a fastening member.

<Repeat of the second step and the third step>
Section A includes a step of securing the steel shell split body installation area W (STEP 4), a step of assembling the steel shell split body 7 (STEP 5), and a step of installing the steel shell split body 7 using the opening reinforcing column 14 (STEP 6). Inside, the steel shell divided body 7 straddling the communication space 12 is sequentially connected in the axial direction of the outer shell tunnel 5 by sequentially repeating in the axial direction of the outer shell tunnel 5.

As a result, as shown in FIG. 10B, all the support works 11 are removed in the section A, and a plurality of steel shell split bodies 7 supported by the opening reinforcing columns 14 are installed over the entire length of the section A.

The steel shell split body 7 installed in the compartment A is connected to each other of the steel shell split bodies 7'installed in advance in other adjacent compartments via a fastening member. Further, it is not always necessary to provide a plurality of steel shell divided bodies 7 in the axial direction in the section A, and in the case of only one body, the second step and the third step are not repeated, and the fourth step is performed. Transition.

<Fourth step: STEP7>
After that, as shown in FIG. 10 (c), after appropriately attaching a tail frame to the steel shell split body 7 assembled over the entire length of the section A, the hollow portion is filled with the filled concrete 8 and a pair of adjacent outer shells are filled. The skeleton split body 6 is constructed so as to straddle the inner sky of the shell tunnel 5 and the communication space 12 (STEP 7).

As described above, although the steel shell split body 7 is provided with the shear reinforcing bar 73, it has a structure that does not require a main bar and a force distribution bar. As a result, the filling property of the filled concrete 8 into the steel shell split body 7 is also good, and the skeleton split body 6 having good quality can be constructed.

Further, in the inner steel shell plate 71 and the outer steel shell plate 72 of the steel shell split body 7, at least the main girders 712, 722, the middle main girders 712', 722', and the vertical ribs 714, 724 have stud girders and the like. By installing the anti-slip member, it is possible to form a structure that enhances the integrity with the filled concrete 8.

<Fifth step: Repeating the first to fourth steps>
In a plurality of compartments A in which the large-section tunnel construction planned area 4 is divided, the above-mentioned first step to the fourth step are sequentially repeated in all of the pair of adjacent outer shell tunnels 5, and the adjacent skeletons are divided. Connect the bodies 6 to each other. As a result, a tubular body composed of the skeleton divided body 6 is constructed in the section A so as to surround the periphery of the large cross-section tunnel construction planned area 4.

<Sixth step: Repeating the first to fifth steps>
The first to fifth steps of constructing a tubular body composed of the skeleton divided body 6 constructed in the section A as described above are divided into a plurality of sections A in which the planned large-section tunnel construction area 4 is divided in the axial direction. B ... Repeat for all. As a result, a tunnel skeleton 9 is constructed in which a tubular body composed of the skeleton divided bodies 6 constructed for each section is continuous and surrounds the entire circumference of the large cross-section tunnel construction planned area 4.

In addition to these operations, as shown in FIG. 3, the space between the outer steel shell plate 72 constituting the steel shell split body 7 and the inner peripheral surface of the outer shell tunnel 5 is filled with the filler 16. It is good to keep it.

In this way, by constructing the tunnel skeleton 9 by a so-called SC structure in which the skeleton split body 6 constructed by filling the steel shell split body 7 with the filled concrete 8 is connected, the work of formwork and rebar work, etc. Since the labor can be significantly reduced, the workability can be improved and the construction time can be significantly shortened even in the narrow inner space of the outer shell tunnel 5 and the communication space 12.

The method for constructing the tunnel skeleton 9 of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the present embodiment, in the third step (STEP 5), the inner steel shell plate 71, the outer steel shell plate 72, and the shear reinforcing bar 73 are separately conveyed, and the steel is steel in the steel shell split body installation region W. It was assembled into the shell split body 7, but the present invention is not necessarily limited to this. These may be assembled into the steel shell split body 7 in advance in a work area such as the ground, and transported to the steel shell split body installation area W via the outer shell tunnel 5.

Further, in the present embodiment, the first to fifth steps are carried out for a pair of adjacent outer shell tunnels 5. However, the outer shell tunnels 5 do not necessarily have to be a pair, and the steps of carrying out the first to fifth steps for a plurality of adjacent outer shell tunnels 5 may be sequentially and repeatedly carried out.

Further, the large cross-section tunnel 3 does not necessarily have ^{to be a tunnel having a finished cross-section exceeding 50 m 2,} and may be a tunnel having any cross-section diameter.

1 Main line shield tunnel 2 Branch line shield tunnel 3 Large section tunnel 4 Large section tunnel Construction planned area 5 Outer shell tunnel 51 Segment 6 Frame split body 7 Steel shell split body 71 Inner steel shell plate 711 Skin plate 712 Main girder 713 Joint plate 714 Vertical Rib 715 Through hole 72 Outer steel shell plate 721 Skin plate 722 Main girder 723 Joint plate 724 Vertical rib 725 Through hole 73 Shear reinforcement 74 Joint part 8 Filled concrete 9 Tunnel frame 10 Water swelling water blocking material 11 Supporting 111 Support work 112 Additional support work 12 Communication space 121 Water stop plate 13 Long stand 14 Opening reinforcement pillar 141 Inner pillar 142 Outer pillar 143 Intermediate pillar 15 Ground improvement part 16 Filling material

Section A Section B Section W Steel shell split body installation area

Claims (5)

It is a method of constructing a tunnel skeleton in which the planned construction area of the tunnel is surrounded by a plurality of outer shell tunnels arranged in parallel and the tunnel skeleton is constructed by using the inner space of the outer shell tunnel.
A plurality of support works are installed in the inner space of the outer shell tunnel at intervals in the axial direction of the outer shell tunnel, and a part of the opposing segments is removed from each of the adjacent outer shell tunnels to communicate with each other. The first step of providing a communication space to be used
The second step of securing the steel shell split body installation area for installing the steel shell split body constituting the tunnel skeleton across the communication space by removing a part of the support work, and
A third step of installing the steel shell split body in the steel shell split body installation area by using an opening reinforcing column capable of stiffening the outer shell tunnel while sandwiching the steel shell split body.
A fourth step of filling the plurality of connected steel shell divided bodies with filled concrete, and
Bei to give a,
The opening reinforcing column is composed of an inner column and an outer column provided coaxially and an intermediate column provided between the two, and the intermediate column is arranged in a hollow portion of the steel shell split body. How to build a tunnel skeleton. The method for constructing a tunnel skeleton according to claim 1.
Prior to the fourth step, the second step and the third step are sequentially repeated in the axial direction of the outer shell tunnel, and the steel shell divided body straddling the communication space is formed in the axial direction of the outer shell tunnel. A method of constructing a tunnel skeleton, which is characterized by sequentially connecting to. The method for constructing a tunnel skeleton according to claim 1 or 2.
A method for constructing a tunnel skeleton, which comprises carrying out the first step to the fourth step for each pair of adjacent outer shell tunnels. The method for constructing a tunnel skeleton according to any one of claims 1 to 3.
A method for constructing a tunnel skeleton, which comprises dividing a planned construction area of the tunnel into a plurality of sections in the axial direction, and carrying out the first step to the fourth step for each section. The method for constructing a tunnel skeleton according to any one of claims 1 to 4.
A method for constructing a tunnel skeleton, which comprises additionally installing a new support between adjacent support works in each of the outer shell tunnels after the communication space is provided in the first step.

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