JP2012077447A - Tunnel connecting structure and tunnel construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tunnel connection structure and a tunnel construction method capable of reducing costs of construction while maintaining the ground subsidence suppression effect on the upper portion of a tunnel connecting section and suppressing a range of ground improvement or ground freezing.SOLUTION: The vertical displacement amount of an upper connection lining 4 can be suppressed against a vertical load from the upper ground by appropriately setting the rise shape of the upper connection lining 4 and connecting positions between the upper connection lining 4 and first and second linings 11, 21 in a tunnel connecting section 3, so that the subsidence amount of the upper ground accompanying the deformation of the upper connection lining 4 can be appropriately suppressed. Therefore, the ground displacement on the upper portion of a tunnel can be suppressed at low costs without requiring increasing of a girder height and/or board thickness to improve cross-sectional rigidity for suppressing the displacement of the tunnel.

Description

  The present invention relates to a tunnel connection structure and a tunnel construction method in which a pair of tunnels adjacent in the horizontal direction are connected to construct one tunnel cross section.

Conventionally, in a tunnel using shield tunnel lining such as a road tunnel, the main line tunnel and the branch line tunnel are connected to form a junction. A structure in which connection linings are installed vertically is proposed (see, for example, Patent Document 1).
In the connection structure described in Patent Document 1, the main line and branch line linings and the upper and lower connection linings are connected so that the cross section of the tunnel junction is an overall oval (oval or egg-shaped). These connecting portions are configured so that the linings are continuous and smoothly curved.

JP 2005-248478 A

  The conventional connection structure described in Patent Document 1 is connected so that the main line and branch line linings and the upper and lower connection linings have a smooth curved surface. For this reason, the arch effect of the tunnel lining is reduced, and the tunnel is shaped to be easily deformed in the vertical direction. Here, for example, in order to enhance the arch effect, it is conceivable to construct a tunnel lining shape having a large rise in the vertical direction so that the entire tunnel becomes a smooth curved surface, but in this case, the ground improvement range becomes large In addition, there may be a large number of connection linings, resulting in an increase in construction costs.

  The objective of this invention is providing the tunnel connection structure and tunnel construction method which can reduce construction cost, maintaining the ground subsidence suppression effect of the upper part of a tunnel connection part.

  The tunnel connection structure of the present invention is a tunnel connection structure in which a first tunnel and a second tunnel adjacent to each other in a substantially horizontal direction are connected to form one tunnel cross section, and the tunnel is a lining of the first tunnel. A first lining composed of the outer portion of the second tunnel, a second lining composed of the outer portion of the lining of the second tunnel, and an upper connection lining connecting the upper portions of the first and second linings; A lower connection lining connecting the lower portions of the first and second linings, and at least the upper connection lining includes a first connection portion connected to the first lining and the A tangent line formed along the upper connection cover at each position of the first connection portion and the second connection portion, formed in an upwardly convex arc shape over the second connection portion connected to the second cover. That tangents along each of the first lining and the second lining do not match. And butterflies.

  According to the present invention as described above, an appropriate rise corresponding to the distance between the first and second tunnels can be ensured without increasing the ground improvement range, and the upper portion acting on the upper connection lining from above. The deformation of the upper connection lining can be suppressed against the earth pressure from the ground, and the amount of settlement of the upper ground accompanying this deformation can be appropriately suppressed.

At this time, in the tunnel connection structure of the present invention, at least the shape of the upper connection lining is such that the apex height of the upper connection lining from a straight line connecting the first connection portion and the second connection portion is the first connection lining. The distance between the first connection portion and the second connection portion is set to about 8% or more and about 40% or less, and the first connection portion is 0 outward from a vertical line passing through the center of the first tunnel. The second connection portion is provided in a range from about 0 ° to about 45 ° outward from a vertical line passing through the center of the second tunnel. It is preferable.
According to such a configuration, the arch effect due to the rise of the upper connection lining is exhibited, and the axial compression force acting on the upper connection lining acts on the first and second linings. The vertical deformation of the outer part of the tunnel occurs, but by appropriately setting the connection position and connection angle of the upper connection lining, the collapse deformation can be minimized, and the subsidence of the upper ground accompanying this deformation The amount can be appropriately controlled. Therefore, during tunnel construction, the impact of subsidence on existing buildings and facilities located on the upper ground is minimized, and temporary construction to prevent subsidence and countermeasures for existing buildings and equipment are omitted or reduced. It is possible to reduce the construction cost and construction period of the entire tunnel construction including the surrounding construction.

In the tunnel connection structure of the present invention, a curved pipe roof is positioned so as to protrude upward at least on the outer peripheral side of the upper connection lining, and the connection position between the curved pipe roof and the first lining and the second lining. Are preferably provided apart from the first connection portion and the second connection portion, respectively.
According to such a configuration, it becomes possible to support the ground by utilizing the rigidity of the pipe roof, so that it is possible to reduce the specification of the upper connection lining and reduce the ground improvement range during construction, , Can improve the safety against the collapse of natural ground.

Furthermore, in the tunnel connection structure of the present invention, it is preferable that, in addition to the curved pipe roof, lock bolts are provided radially on the ground from the inside of the tunnel of the curved pipe roof and connected to the curved pipe roof.
According to such a configuration, the earth pressure acting on the pipe roof can be reduced by supporting the pipe roof on the surrounding ground by the lock bolt, so that the deformation of the surrounding ground can be further suppressed, and the construction cost due to the reduction of the material specifications can be reduced. Reduction and improvement of safety during construction can be achieved.

Further, in the tunnel connection structure of the present invention, the first lining and the second lining, and the upper connection lining and the lower connection lining are each formed of reinforced concrete and steel structure having a steel shell. Or a composite structure made of steel shell and concrete, or a plurality of segments made of a combination thereof.
According to such a configuration, the structure of the segment can be properly used according to the performance required for the tunnel lining, and the upper and lower connection linings are connected via the connection portions corresponding to various segments. Only a tunnel junction can be constructed.

On the other hand, the tunnel construction method of the present invention is a tunnel construction method using any one of the above tunnel connection structures, and after the first and second tunnel constructions, depending on the case, from one of the tunnel inner sides to the other side The pipe roof is constructed up to the tunnel, and the surrounding ground where the upper connecting lining and the lower connecting lining are installed is improved from the inside of the tunnel to stabilize the surrounding ground. Supporting the lining and the second lining, partially excavating the ground in the tunnel, and if necessary, installing rock bolts radially on the ground from the inside of the tunnel of the pipe roof, It is characterized by constructing a work and a lower connection lining, and removing a removal part lining and a supporting work.
Here, the support work is preferably a type in which a steel member such as H steel is fixed with a member such as a bolt because the construction time can be shortened.
At this time, in order to reduce the ground improvement range around the installation position of the upper connection lining, after the construction of the first and second tunnels in advance, a curved pipe roof is constructed so as to connect the cross sections from both tunnels, The ground may be improved only around it, or a lock bolt may be installed in addition to the ground improvement in order to prevent the collapse of the ground around the installation position of the upper connection lining. Furthermore, when installing a curved pipe roof, it is preferable to backfill the space formed by the pipe roof and the upper connection lining after the upper connection lining is installed.
According to such a construction method, the rigidity of the pipe loop can be used to support the surrounding ground, so the ground improvement range and excavation range can be minimized, leading to reduction of construction costs and the natural ground during construction. Safety against collapse can be improved.

  According to the tunnel connection structure and the tunnel construction method of the present invention as described above, the arch effect is utilized for the earth pressure acting by ensuring an appropriate rise in the connection lining according to the separation distance of the tunnel. Since deformation of the tunnel can be suppressed, the amount of land subsidence at the top of the tunnel can be reduced. This will not increase the tunnel lining thickness, and will eliminate the need for work to deal with existing buildings and facilities, etc. it can.

It is sectional drawing which shows the tunnel junction part using the connection structure of this invention. It is a figure which shows the other shape of the said tunnel junction part. It is a figure which shows the further another shape of the said tunnel junction part. It is a figure which shows other shapes of the said tunnel. It is a figure which shows other shapes of the said tunnel. It is a figure which shows other shapes of the said tunnel. It is a figure which shows the analysis model which concerns on the Example of the said tunnel junction part. It is a graph which shows the relationship between the rise ratio and vertical displacement in the said Example. It is a graph which shows the relationship between the rise ratio and displacement rigidity in the said Example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the tunnel connection structure of the present invention constructs a tunnel junction 3 by connecting a main tunnel 1 as a first tunnel and a branch tunnel 2 as a second tunnel adjacent to each other in the horizontal direction. Is. The main line tunnel 1 and the branch line tunnel 2 are shield tunnels that extend in the longitudinal direction of the tunnel, which is the depth direction of FIG. 1, respectively. In the present embodiment, each of the centers O1, O1 of the main line tunnel 1 and the branch line tunnel 2 is shown. A connection structure at a position where O2 is adjacent to each other by a distance (distance between centers) L will be described. Note that the center-to-center distance L may vary depending on the position in the tunnel front-rear direction.

  The main tunnel 1 and the branch tunnel 2 are each configured by connecting a plurality of segments in the tunnel longitudinal direction and the tunnel circumferential direction. That is, the main line tunnel 1 and the branch line tunnel 2 assemble a segment in a space formed by excavating a natural ground with a shield machine (excavator), and take a reaction force on the assembled segment and advance the shield machine with a jack. In addition, the procedure of excavating the natural ground has been built repeatedly. Here, each segment may be an RC structure formed from reinforced concrete, a steel structure having a steel shell, or a composite structure in which concrete is packed inside the steel shell. There may be.

  The tunnel junction 3 is constructed between the main tunnel 1 and the branch tunnel 2 constructed in advance as described above, and is a first lining composed of the outer portion of the lining of the main tunnel 1. 11, a second lining 21 made of an outer portion of the lining of the branch tunnel 2, an upper connection lining 4 connecting the upper ends of the first lining 11 and the second lining 21, and a first lining 11 and a lower connection lining 5 that connects the lower ends of the second lining 21. In addition, the lining 12 of the inner portion of the main tunnel 1 other than the first lining 11 and the lining 22 of the inner portion of the branch tunnel 2 other than the second lining 21 should be removed after the tunnel junction 3 is constructed. Thus, a large space is formed inside the tunnel junction 3.

  The upper connection lining 4 is formed in an upwardly protruding arc shape across the first connection portion 41 connected to the first lining 11 and the second connection portion 42 connected to the second lining 21. Yes. On the other hand, the lower connection lining 5 is formed symmetrically with the upper connection lining 4, that is, the fourth connection connected to the third connection 51 and the second lining 21 connected to the first lining 11. A circular arc projecting downward is formed across the connecting portion 52. And as a structure of each connection part 41,42,51,52, a suitable connection structure can be selected according to the material and structure of each segment, for example, each connection part 41,42,51,52 is suitably used. It may be configured with a segment piece and combined with the first and second linings 11 and 21, and in that case, a connection structure using an appropriate anchor material, mechanical joint, or the like can be employed. Further, when the first and second linings 11 and 21 and the upper and lower connection linings 4 and 5 are made of steel, the connection portions 41, 42, 51, and 52 joined to each other by welding are used. Alternatively, when the first and second linings 11 and 21 and the upper and lower connection linings 4 and 5 are RC structures, the connection portions 41 and 42 of on-site RC structure or precast RC structure (PCa) 51 and 52 may be used.

  The shape of such an upper connection lining 4 is set as follows. Here, the dimensions of each part are based on the cross sections of the center lines P1, P2, which are vertical lines passing through the centers O1, O2 of the main tunnel 1 and the branch tunnel 2, and the first and second linings 11, 21 ( (Thickness) center lines Q1 and Q2 and the center line R of the cross section (thickness) of the upper connecting lining 4 and the intersections of the center lines Q1 and Q2 and the center line R are the first intersection X1 and the second intersection, respectively. Let X2 be a straight line connecting these intersections X1 and X2 as a rise reference line Y. In addition, since the lower connection lining 5 has a vertically symmetrical shape with the upper connection lining 4, description of the shape is omitted.

The arc shape that is convex above the upper connection lining 4, that is, the rise shape, has a distance a between the first intersection point X 1 of the first connection portion 41 and the second intersection point X 2 of the second connection portion 42, and the intersection points X 1 and X 2. It is defined by the relationship with the height dimension b from the connecting rise reference line Y to the apex T of the upper connection lining 4, that is, the rise ratio (b / a). And in the tunnel junction part 3 of this embodiment, the rise ratio (b / a) of the upper connection lining 4 (and the lower connection lining 5) is set to 8% or more and 40% or less. That is, the rise ratio (b / a) is set so as to satisfy the following expression (1).
0.08 ≦ b / a ≦ 0.4 (1)

In addition, the connection position between the upper connection lining 4 and the first lining 11 is defined by the position of the first intersection X1 of the first connection portion 41, specifically, the first intersection X1 and the center of the main tunnel 1 It is defined by the intersection angle θ1 between the straight line S1 passing through O1 and the center line P1 of the main tunnel 1. On the other hand, the connection position between the upper connection lining 4 and the second lining 21 is defined by the position of the second intersection X2 of the second connection portion 42. Specifically, the second intersection X2 and the center of the branch tunnel 2 are specified. It is defined by the intersection angle θ2 between the straight line S2 passing through O2 and the center line P2 of the branch line tunnel 2. Here, the intersection angles θ1 and θ2 are set so as to be positive from the centerlines P1 and P2 toward the outside. And in the tunnel junction part 3 of this embodiment, intersection angle (theta) 1 and (theta) 2 which are the connection positions of the upper connection lining 4 (and lower connection lining 5) are set to the range of 0 degree or more and 45 degrees or less. . That is, the intersection angle θ1 is set so as to satisfy the following expression (2), and the intersection angle θ2 is set so as to satisfy the following expression (3).
0 ° ≦ θ1 ≦ 45 ° (2)
0 ° ≦ θ2 ≦ 45 ° (3)

  As an example of the tunnel junction 3 that defines the shape and connection position as described above, the upper connection lining 4 (and the lower connection lining 5) shown in FIG. 1 has a rise ratio (b / a) set to 25%. The intersection angle θ1 is set to 22.5 °, and the intersection angle θ2 is set to 22.5 °. In the example shown in FIG. 2, the rise ratio (b / a) is set to 8%, the crossing angle θ1 is set to 0 °, and the crossing angle θ2 is set to 0 °. Further, in the case shown in FIG. 3, the rise ratio (b / a) is set to 40%, the crossing angle θ1 is set to 45 °, and the crossing angle θ2 is set to 45 °.

The tunnel construction procedure shown in FIG. 5 is that after the main tunnel 1 and the branch tunnel 2 are constructed, the curved pipe roof 6 is constructed from one of the tunnels to the opposite tunnel, and the ground improvement is made from the curved pipe roof 6. The improved ground 7 is formed by injecting material or frozen material into the ground. Further, the ground around the position where the lower connection lining is to be installed from the inside of the tunnel is improved and stabilized, and the supporting work 9 is installed, and the ground between the main tunnel 1 and the branch tunnel 2 is excavated. Next, the connection portions 41 and 42 and the upper connection lining 4 are constructed between the first lining 11 and the second lining 21. Similarly, the connecting portions 51 and 52 and the lower connection lining 5 are constructed between the first lining 11 and the second lining 21. Thereafter, the removal part linings 12 and 22 and the support work 9 are removed.
The tunnel construction procedure shown in FIG. 6 is basically the same as that shown in FIG. 5, but after construction of the curved pipe roof 6, the curved pipe roof 6 is drilled into the curved pipe roof 6 and the lock bolt 13 is installed. Construction is added. Alternatively, the rocks 13 may be formed by drilling a natural ground from the tunnel, and may be coupled to the curved pipe roof 6 via a connecting material (not shown).

Hereinafter, with respect to the embodiments of the present invention, an FEM analysis model in which the main tunnel 1, the branch tunnel 2 and the tunnel junction 3 are modeled, the rise ratio (b / a) and the intersection angles θ1 and θ2 are used as parameters. The result of having examined the amount of subsidence (vertical displacement) of the vertex T of the upper connection lining 4 by applying a load from the ground will be described.
As parameters of intersection angles θ1 and θ2 that are connection positions of the upper connection lining 4 and the first and second linings 11 and 21, three types of 0 °, 22.5 °, and 45 °, respectively, and −22.5 A range of 0% to 40% was set as a parameter for the rise ratio (b / a).
An analysis model of this example is shown in FIG. The analysis model uses a uniform rigidity model of one ring, and the ground is evaluated with an appropriate spring (see FIG. 7B), and earth pressure and water pressure from the ground side are added as loads (FIG. 7A). See)). The first lining 11, the second lining 21, the upper connection lining 4 and the lower connection lining 5 in the analysis model are composed of steel segments having steel shells, and the cross section is shown in FIG. As shown, it has a pair of main girders with a girder height of 1000 mm and a plate thickness of 90 mm, and a skin plate with a plate thickness of 6 mm that connects these main girders on the ground mountain side. Table 1 shows the specifications of the analysis model.

FIG. 8 and FIG. 9 are graphs showing the relationship between the rise ratio and the vertical displacement amount, and the rise ratio and displacement rigidity based on the analysis results. Here, in FIG. 9, the reciprocal of the ratio of the vertical displacement amount of the other model to the vertical displacement amount when the rise ratio (b / a) is 0% is expressed as displacement stiffness.
As shown in FIG. 8, the vertical displacement amount decreases as the rise ratio (b / a) increases from 0% when the crossing angles θ1, θ2 are 0 °, 22.5 °, and 45 °, When the rise ratio (b / a) is about 20%, the minimum value is reached, and the rise ratio (b / a) is maintained at the minimum value from 20% to 40% or slightly increased. As shown in FIG. 9, the displacement rigidity is such that the rise ratio (b / a) is about 8% to about 40% in each of the intersection angles θ1, θ2 of 0 °, 22.5 °, and 45 °. It can be seen that, in the range, a bending rigidity of 2 times or more of the rise ratio (b / a) of 0% is secured.

  According to the above embodiment, the above-mentioned formulas (1) to (3) are satisfied as the rise shape of the upper connection lining 4 in the tunnel junction 3 and the connection position with the first and second linings 11 and 21. If so, the vertical displacement amount of the upper connection lining 4 can be suppressed with respect to the vertical load from the upper ground, and the amount of subsidence of the upper ground accompanying this deformation can be appropriately suppressed. Therefore, during tunnel construction, the impact of subsidence on existing buildings and facilities located on the upper ground is minimized, and temporary construction to prevent subsidence and countermeasures for existing buildings and equipment are omitted or reduced. It is possible to reduce the construction cost and construction period of the entire tunnel construction including the surrounding construction.

  Moreover, as shown in FIG. 5, the ground improvement range can be suppressed by constructing the pipe roof 6 on the outside of the upper connection lining 4 and constructing the upper connection lining 4 after freezing the ground. Moreover, as shown in FIG. 6, the safety | security to the collapse of a natural ground at the time of construction can be improved by constructing the lock bolt 13 from the inside of the pipe roof 6 to the outer peripheral ground after the construction of the pipe roof. Further, the connection structure between the pipe roof 6 and the main line tunnel 1 and the branch line tunnel 2 can be regarded as a rigid connection or a pin connection so that the rigidity of the main body of the pipe roof 6 can be utilized. Can be reduced. Further, when the ground around the pipe roof 6 is improved, it is desirable that the material has a high water-stopping property or can improve the water-stopping property in order to surely carry out water-stopping during construction. Moreover, when the ground of the outer side of the lower connection lining 5 is improved, in order to surely perform water stop at the time of construction, the material is preferably high in water stop. 4 shows a tunnel cross section at the time of completion, and FIG. 5 shows a tunnel cross section at the time of construction.

In addition, this invention is not limited to the said embodiment, Including other structures etc. which can achieve the objective of this invention, the deformation | transformation etc. which are shown below are also contained in this invention.
For example, in the above-described embodiment, the lower connection lining 5 is formed to be vertically symmetrical with the upper connection lining 4. However, the present invention is not limited thereto, and the upper connection lining 4 and the lower connection lining 5 are different from each other. It is good also as a shape and a connection position.
Further, in the above embodiment, the main tunnel (first tunnel) 1 and the branch tunnel (second tunnel) 2 are shield tunnels constructed by combining a plurality of segments. The tunnel structure and construction method can be arbitrarily selected as appropriate.

In addition, the best configuration, method and the like for carrying out the present invention have been disclosed in the above description, but the present invention is not limited to this. That is, the invention has been illustrated and described with particular reference to certain specific embodiments, but without departing from the spirit and scope of the invention, Various modifications can be made by those skilled in the art in terms of material, quantity, and other detailed configurations.
Therefore, the description limiting the shape, material, etc. disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded the limitation of one part or all of such restrictions is included in this invention.

  DESCRIPTION OF SYMBOLS 1 ... Main line tunnel (1st tunnel), 2 ... Branch line tunnel (2nd tunnel), 3 ... Tunnel junction, 4 ... Upper connection lining, 5 ... Lower connection lining, 6 ... Curve pipe roof, 7, 8 ... Improved ground, 9 ... supporting work, 11 ... first lining, 12 ... removal part lining, 13 ... lock bolt, 21 ... second lining, 22 ... removal part lining, 41 ... first connecting part, 42 ... 2nd connection part, 51 ... 3rd connection part, 52 ... 4th connection part, a ... Separation distance of connection part of connection lining, L ... Distance between tunnel centers, b ... Vertex height dimension, T ... Vertex.

Claims (6)

A tunnel connection structure in which a first and second tunnels adjacent in a substantially horizontal direction are connected to form one tunnel cross section,
The tunnel includes a first lining comprising an outer portion of the lining of the first tunnel, a second lining comprising an outer portion of the lining of the second tunnel, and the first and second linings. An upper connection lining connecting the upper portions, and a lower connection lining connecting the lower portions of the first and second linings,
At least the upper connection lining is formed in an arc shape protruding upward across a first connection portion connected to the first lining and a second connection portion connected to the second lining, A tunnel connection characterized in that a tangent along the upper connection lining does not coincide with a tangent along each of the first lining and the second lining at each position of the first connection portion and the second connection portion. Construction. The tunnel connection structure according to claim 1,
At least the shape of the upper connecting cover is such that the apex height of the upper connecting cover from the straight line connecting the first connecting portion and the second connecting portion is the distance between the first connecting portion and the second connecting portion. It is set to about 8% or more and 40% or less with respect to the distance,
The first connection portion is provided in a range of about 0 ° or more and about 45 ° or less outward from a vertical line passing through the center of the first tunnel, and the second connection portion extends from the center of the second tunnel. A tunnel connection structure, characterized in that the tunnel connection structure is provided in a range of about 0 ° to about 45 ° from the vertical line passing through to the outside. In the tunnel connection structure according to claim 1 or 2,
A curved pipe roof is positioned so as to protrude upward at least on the outer peripheral side of the upper connection lining, and the connection position between the curved pipe roof and the first lining and the second lining is the first connection portion and the second connection. A tunnel connection structure characterized by being provided apart from each part. In the tunnel connection structure according to claim 3,
A tunnel connection structure characterized in that, in addition to the curved pipe roof, lock bolts are provided radially on the ground from the inside of the tunnel of the curved pipe roof and connected to the curved pipe roof. In the tunnel connection structure according to any one of claims 1 to 4,
The first lining and the second lining and the upper connection lining and the lower connection lining are RC structures formed from reinforced concrete, steel structures having steel shells, or composite structures consisting of steel shells and concrete, respectively. A tunnel connection structure comprising a plurality of segments comprising any one of the above structures or a combination thereof. A tunnel construction method using the tunnel connection structure according to any one of claims 1 to 5,
After construction of the first and second tunnels, a pipe roof is constructed from one of the tunnels inside to the other side of the tunnel in some cases, and around the position where the upper connection lining and the lower connection lining are installed from inside the tunnel The ground is improved to stabilize the surrounding ground, and then a supporting work is installed to support the first lining and the second lining, and after partially excavating the ground in the tunnel, Tunnel construction characterized by constructing rock bolts radially on the ground from the inner side of the tunnel of the pipe roof, constructing the upper connection lining and the lower connection lining, and removing the removal portion lining and supporting work Method.

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