JP2014043738A - Construction method of heavy-section tunnel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a construction period from being prolonged or cost from being increased, by reducing an underground occupant area of a starting portion of an outer shell shield tunnel which is constructed outside of a main-track shield tunnel in construction of an underground cavity part.SOLUTION: According to a construction method of a heavy-section tunnel, a main-track shield tunnel 1 is constructed, a circumferential shield starting base 3 is constructed by enlarging a portion of the main-track shield tunnel 1, and a ring-shaped outer shell shield starting base 4 is constructed by performing circumferential excavation from the circumferential shield starting base 3 along an outer circumferential surface 1a of the main-track shield tunnel 1 by means of a circumferential shield machine. A plurality of outer shell shield tunnels 2 are constructed by starting an outer shell shield machine 6 from a sidewall part 41B of the outer shell shield starting base 4, and the outer shield tunnel 2 is started from the outer shell shield starting base 4 in parallel with the main-track shield tunnel 1 and directed away from the main-track shield tunnel 1 to the radial outside gradually with progress of excavation.

Description

  The present invention relates to a method for constructing a large-section tunnel for constructing an underground cavity provided by widening the outside of a main shield tunnel.

Conventionally, when excavating the underground and constructing underground cavities, the construction is performed in a state where a plurality of outer shell shield tunnels are arranged at predetermined intervals outside the planned construction position of the underground cavity. There is a known method of constructing a shield roof tip receiving work that surrounds the roof.
In the method of constructing the underground cavity by adopting such shield roof tip receiving construction, the cylindrical lining wall including the necessary space of the underground cavity is formed by, for example, an outer shell shield tunnel having an outer diameter of about 4 m. A plurality of outer shield tunnels are started from shield tunnels that are configured and preceded (see, for example, Patent Document 1).

  In Patent Document 1, when constructing a branch and junction between the main shield tunnel and the lamp shield tunnel, the lamp shield tunnel is advanced ahead of the main shield tunnel, and the roof shield machine is started from the vicinity of the tip of the lamp shield tunnel. A method of constructing a shield roof tip receiving work that surrounds a branch junction by constructing a number of roof shield tunnels (outer shell shield tunnels) in a state of being closely arranged along the contour of the junction outside the branch junction It is disclosed.

Japanese Patent No. 4803428

However, the conventional large-section tunnel construction method described above has the following problems.
That is, in the case of Patent Document 1, since it is difficult to start from the outer peripheral surface of the preceding shield tunnel in a direction parallel to the tunnel axial direction, the shield immediately after starting from the outer peripheral surface of the tunnel toward the outside in the radial direction. A sharply curved section that turns the machine rapidly is provided to change the direction of excavation in a target direction, for example, a direction parallel to the preceding shield tunnel. For this reason, the sharply curved section immediately after the start spreads outward in the radial direction from the preceding shield tunnel, so if the land occupational restrictions are severe in urban areas etc., the construction is restricted and the section ground rights There are problems that it takes time to set, the construction period becomes long, and the cost may increase.

  The present invention has been made in view of the above-mentioned problems, and in the construction of underground cavities, it is possible to reduce the underground occupation area of the start portion of the outer shell shield tunnel constructed outside the main shield tunnel. An object of the present invention is to provide a method for constructing a large-section tunnel capable of suppressing an increase in construction period and cost.

  In order to achieve the above object, in the construction method of a large cross-section tunnel according to the present invention, when excavating the underground and constructing the underground cavity, a plurality of external tunnels are previously placed outside the planned excavation position of the underground cavity. A construction method of a large-section tunnel that constructs an outer shell body that surrounds the planned excavation position with the outer shell shield tunnel by constructing the shell shield tunnel in an array, and excavates the inside of the outer shell body. A process of constructing a shield tunnel, a process of constructing a circumferential shield starting part that is a part of the circumferential direction of the main shield tunnel, and a circumferential shield machine from the circumferential shield starting part along the outer peripheral surface of the main shield tunnel Drilling in the circumferential direction and constructing the ring-shaped outer shell shield starting part, and the tunnel axis direction of the main shield tunnel at the outer shell shield starting part Starting a shell shield machine from a side wall portion having intersecting planes and constructing a plurality of shell shield tunnels, and the shell shield tunnel is parallel to the main shield shield tunnel from the shell shield start portion It is characterized by being constructed by digging in the direction away from the main shield tunnel in the radial direction gradually as it digs up.

In the present invention, a circumferential shield starting portion is formed in a part of the circumferential direction at an arbitrary position of the main shield tunnel, and a ring is formed along the outer peripheral surface of the main shield tunnel from the circumferential shield starting portion using a circumferential shield machine. The part excavated in the shape can be used as a starting base (outer shield starting part) of the outer shell shield machine. The outer shell shield machine with the excavation surface facing the side wall of the outer shell shield starting part is placed, and the outer shell shield machine is linearly started along the main shield tunnel and parallel to the main shield tunnel Can dig into. Then, immediately after the start, a plurality of outer shell shield tunnels can be formed on the outer periphery side of the main shield tunnel by forming a curved portion that is separated from the main shield tunnel in the radial direction at an appropriate position. .
Therefore, it becomes possible to build an outer shell body by integrally connecting the outer shell shield tunnels adjacent in the circumferential direction by an appropriate connecting means, and this outer shell body covers the outside of the main shield tunnel. Therefore, it is possible to excavate the inside of the outer shell body and construct an underground cavity with a large cross section.

  Further, in the present invention, the height dimension in the radial direction of the outer shell shield starting part formed in a ring shape is slightly larger than the extent that the outer shell shield machine can be arranged, that is, the excavation diameter (diameter) of the outer shell shield machine. It is only necessary to ensure the dimensions, and the starting pit of the outer shell shield machine that is excavated from the outer shell shield starting portion becomes the side wall portion of the outer shell shield starting portion. Therefore, the construction area of the starting part of the outer shell shield machine does not expand beyond the diameter dimension of the outer shell starting part.

  Thus, in the present invention, it is not necessary to start from the outer peripheral surface of the main shield tunnel to the outside in the radial direction, and the size of the outer shell shield starting portion can be minimized. Construction that suppresses the expansion of the construction area in the starting part of the can be made, and it is not necessary to turn the outer shell shield machine rapidly as in the prior art, and efficient construction is possible.

  Further, in the construction method of the large-section tunnel according to the present invention, a plurality of shell shield machines are arranged along the circumferential direction in the shell shield starting part, and the shell shield machines are dug simultaneously. Good.

  According to the construction method of the large-section tunnel of the present invention, since the outer shell shield starting part is formed in a ring shape, a plurality of outer shell shield machines are arranged along the circumferential direction of the outer shell shield starting part. The plurality of shell shield machines can be started at the same time to construct a plurality of shell shield tunnels at the same time, thereby shortening the construction period.

  According to the construction method of the large section tunnel of the present invention, in the construction of the underground cavity, the underground occupation area of the starting portion of the outer shield tunnel constructed outside the main shield tunnel can be reduced, and the construction period is The increase in length and cost can be suppressed.

It is a perspective view which shows the outline | summary of the construction method of the large section tunnel by embodiment of this invention. It is a sectional side view of the construction method shown in FIG. It is the sectional view on the AA line shown in FIG. It is a perspective view which shows the state which constructs an outer shell shield start base with a circumferential shield machine.

  Hereinafter, the construction method of the large section tunnel by embodiment of this invention is demonstrated based on drawing.

As shown in FIG. 1 and FIG. 2, the construction method of the large section tunnel according to the present embodiment is intended to excavate the underground cavity 10 when constructing the underground cavity 10 such as a road tunnel having a large section, for example. The main shield tunnel 1 is preliminarily constructed inside the position, and a plurality of outer shield tunnels 2 are constructed outside the main shield shield 1 so that the outer shield tunnel 1 surrounds the main shield tunnel 1. The shell 20 is constructed, and the underground cavity 10 is constructed by excavating the inside of the outer shell 20. Here, the main line shield tunnel 1 and the outer shell shield tunnel 2 are constructed by a conventional shield method.
Here, the tunnel axis direction in the main shield tunnel 1 is indicated by a symbol X.
In FIG. 1, a part of the plurality of outer shell shield tunnels 2 (located on the front side in the drawing) is omitted for easy viewing.

  The construction method of the underground hollow portion 10 of the present embodiment includes a step of constructing the main shield tunnel 1 and a circumferential shield start base 3 (a portion of the start base portion 1A in the main shield tunnel 1 which is widened in the circumferential direction). (Circumferential shield start part) and a ring-shaped excavation in the circumferential direction along the outer peripheral surface 1a of the main shield tunnel 1 from the peripheral shield start base 3 by the peripheral shield machine 5 (see FIG. 4) The process of constructing the outer shell shield starting base 4 (outer shell starting section) and the outer shell shield machine 6 from the side wall 41B having a plane perpendicular to the tunnel axis direction X of the main shield tunnel 1 in the outer shell starting base 4 , And a plurality of (16 in the illustrated example of FIG. 3) outer shell shield tunnels 2 are constructed.

The outer shell shield tunnel 2 is started in parallel with the main shield tunnel 1 from the outer shield start base 4, and is gradually dug in a direction away from the main shield tunnel 1 in the radial direction as it is dug.
The outer shell shield tunnel 2 is constructed by digging a plurality of outer shell shield machines 6 arranged along the circumferential direction in the outer shell start base 4 simultaneously or in an appropriate order.

  In this embodiment, the diameter of the main shield tunnel 1 is about 16 m, for example, the outer diameter of the outer shield starting base 4 formed by excavation of the circumferential shield machine 5 is about 28 m, and the height in the radial direction is It is assumed that the length in the tunnel axis direction of the outer shield start base 4 (the length in the direction parallel to the central axis of the outer shield start base 4) is about 12.3 m. .

Next, the construction method of the large section tunnel will be described in more detail based on the drawings.
In the present embodiment, as shown in FIG. 4, when the main shield tunnel 1 reaches a predetermined predetermined position, after assembling the primary segment and the guide rings 51A and 51B in consideration of dismantling, further excavation is performed. to continue. Then, in the start base part 1A of the main shield tunnel 1, a donut-shaped (ring-shaped) outer shield start base 4 (see FIG. 1) is built around the main shield tunnel 1 by the circumferential shield machine 5. The outer shell shield machine 6 (see FIG. 2) is started from inside the departure base.

  Specifically, as shown in FIG. 4, a pair of ring-shaped guide rings 51 </ b> A and 51 </ b> B for guiding the circumferential shield machine 5 at the time of excavation of the starting base portion 1 </ b> A in the main shield tunnel 1 It is provided so as to extend along 1a. In addition, in order to facilitate the segment removal work accompanying the excavation of the circumferential shield launch base 3 and the circumferential shield machine 5 in the launch base portion 1A of the main shield tunnel 1 between the guide rings 51A and 51B, The multi-segment segment 11 is assembled.

  Next, at the bottom of the main shield tunnel 1 between the guide rings 51A and 51B, the multi-segment segment 11 is disassembled, removed, and excavated while being piled to form a box-shaped circumferential shield start base 3. To do. Then, the circumferential shield machine 5 is assembled and installed in the circumferential shield start base 3.

  Here, the circumferential shield machine 5 includes an excavation face plate 52 and a skin plate 53 having a rectangular cross section. The inner peripheral plate 53 </ b> A (the main shield tunnel 1 side) and the outer peripheral plate 53 </ b> B of the skin plate 53 form an arc plate shape coaxial with the main shield shield 1. Sliding portions 54A and 54B that are movably engaged with the guide rings 51A and 51B are provided at front and rear edge ends in the tunnel axial direction X of the inner peripheral plate 53A. That is, the circumferential shield machine 5 digs along the outer peripheral surface 1a of the main shield tunnel 1 while guiding the sliding portions 54A and 54B to the guide rings 51A and 51B, and in the tail of the circumferential shield machine 5, The ring-shaped outer shield start base 4 along the outer peripheral surface 1a of the main shield tunnel 1 is constructed by sequentially assembling the U-shaped circumferential segments 41 in a cross-sectional view and performing lining.

  The circumferential segment 41 constituting the outer shell shield starting base 4 includes a circumferential wall portion 41A assembled in the tunnel circumferential direction coaxial with the main shield tunnel 1, and both front and rear ends in the tunnel axial direction X of the circumferential wall portion 41A. It consists of side wall parts 41B and 41C which block the opening between the outer peripheral surface 1a of the main line shield tunnel 1 (refer FIG. 1). Here, the height dimension in the radial direction of the side walls 41B and 41C is set to be larger than the radial dimension of the outer shell shield machine 6, and the outer shell shield machine 6 shown in FIG. 1 and FIG. The dimension is such that the vehicle can start in a state parallel to X.

  Next, the mountain shield on the front face of the circumferential shield machine 5 is removed, the excavation of the circumferential shield machine 5 is started, backfilling is performed, the circumferential segment 41 is assembled, and the main shield tunnel 1 can be removed. By repeatedly removing the multi-segmented segment 11 and digging the outer side of the main shield tunnel 1 in the circumferential direction, the outer shield start base 4 extending over the entire circumference of the main shield tunnel 1 is constructed. .

  Next, as shown in FIG. 2, in the outer shell shield starting base 4, the outer shell shield machine 6 having a plurality of circular cross sections, the excavation face plate 61 of the circumferential segment 41, and the side wall portion on the front side in the tunnel axial direction X are provided. A plurality of outer shield tunnels 2 are constructed by being installed opposite to 41B and started parallel to the tunnel axial direction X, and the outer periphery of the main shield tunnel 1 is composed of a plurality of outer shield tunnels 2. Build the shell 20.

  That is, the outer shell shield tunnel 2 that has started is dug almost parallel to the tunnel axis direction X immediately after the start to form the first straight portion 2A, and when the appropriate distance is dug, for example, the body of the outer shell shield machine 6 When the entire unit advances from the outer shell shield starting base 4 into the ground, it is dug away from the main shield tunnel 1 while bending away from the main shield tunnel 1 to form a curved portion 2B. A single outer shield tunnel 2 is constructed by forming a second straight portion 2C parallel to the main shield tunnel 1 at a position in the radial direction.

Next, between the outer shell shield tunnels 2 and 2 that are adjacent to each other in the circumferential direction among the plurality of outer shell shield tunnels 2 that have been constructed, the ground is improved by a freezing method, a chemical injection method, etc. Integration is achieved by connecting as a structure, thereby forming an outer shell 20 having a support function and a water stop function. The outer shell 20 gradually expands from the departure base portion 1A of the main shield tunnel 1 toward the traveling direction, and forms a second straight portion 2C when reaching a predetermined diameter. In this case, the second straight portion 2C may not be formed depending on the necessity of the internal space.
In addition, the outer shell shield machine 6 excavates the outer shield tunnel 2, reaches the anchor wall planned point of the branch widening part, disassembles and collects it, and then assembles and starts again at the outer shell shield starting base 4. You may make it use repeatedly so that the outer shell shield tunnel 2 may be constructed.

  After that, while dismantling and removing the segment near the anchorage wall of the main shield tunnel 1 at the planned anchor wall site, excavating the inside of the outer shell 20 while constructing the anchor wall, the inside of the shield roof of the main shield tunnel 1 The remaining segments are disassembled and removed to form the underground cavity 10.

Next, the effect | action of the construction method of the large cross-sectional tunnel mentioned above is demonstrated in detail based on drawing.
As shown in FIG. 4, in the present embodiment, a circumferential shield start base 3 is formed at a part in the circumferential direction at an arbitrary position of the main shield tunnel 1, and the circumferential shield machine 5 is connected to the circumferential shield start base 3. The portion excavated in a ring shape along the outer peripheral surface 1 a of the main shield tunnel 1 can be used as the outer shield starting base 4 of the outer shell shield machine 6. As shown in FIGS. 1 and 2, an outer shell shield machine 6 with the excavation surface facing the side wall 41 </ b> B of the outer shell shield start base 4 is arranged, and the outer shell shield machine 6 is straight along the main shield tunnel 1. It is possible to start the vehicle in a direction parallel to the main shield tunnel 1.
Then, immediately after the start, a plurality of outer shell shield tunnels 2 are formed on the outer peripheral side of the main shield tunnel 1 by forming a curved portion 2B that is separated from the main shield tunnel 1 in the radial direction at an appropriate position. can do.

  For this reason, the outer shell shield tunnels 2 adjacent to each other in the circumferential direction are integrated by connecting them as a slit structure after performing ground improvement by an appropriate auxiliary method, that is, the above-described freezing method or chemical injection method. It is possible to build the outer shell 20 by connecting to the outer shell 20, and this outer shell 20 constitutes a roof shield that covers the outside of the main line shield tunnel 1, so that the inside of the outer shell 20 is excavated to have a large cross section. The underground cavity 10 can be constructed.

  The height of the outer shield shield base 4 formed in a ring shape in the radial direction is such that the outer shield machine 6 can be disposed, that is, a dimension slightly larger than the excavation diameter (diameter) of the outer shield machine 6. And the start pit of the outer shell shield machine 6 excavated from the outer shield start base 4 becomes the side wall 41B of the outer shield start base 4. Therefore, the construction area of the start part of the outer shell shield machine 6 does not expand beyond the diameter dimension of the outer shield start base 4.

  Thus, in this embodiment, it is not necessary to start from the outer peripheral surface 1a of the main shield tunnel 1 to the outside in the radial direction, and the size of the outer shell shield starting base 4 can be minimized. Thus, it is possible to perform construction while suppressing the expansion of the construction area in the starting part of the outer shell shield machine 6, and it is not necessary to make the outer shell shield machine 6 turn sharply as in the prior art, and efficient construction is possible.

  Further, since the outer shell shield starting base 4 is formed in a ring shape, a plurality of outer shell shield machines 6 can be arranged along the circumferential direction of the outer shell shield starting base 4. The shell shield machine 6 can be started at the same time to construct a plurality of outer shield tunnels 2 at the same time, and the construction efficiency can be improved.

  As described above, in the construction method of the large section tunnel according to the present embodiment, in the construction of the underground cavity 10, the underground occupation area of the starting portion of the outer shield tunnel 2 constructed outside the main shield tunnel 1 is reduced. It is possible to suppress the increase in construction period and cost.

As mentioned above, although embodiment of the construction method of the large section tunnel by this invention was described, this invention is not limited to said embodiment, In the range which does not deviate from the meaning, it can change suitably.
For example, in this embodiment, the digging direction of the outer shell shield machine 6 is set to the front in the same direction as the digging direction of the main shield tunnel 1, but is not limited to this direction, and is behind the outer shell shield starting portion. You may make it start toward. That is, the outer shell shield tunnel 2 can be provided on the front side or the rear side of the outer shell shield starting portion. In short, any method may be used as long as the outer shell shield machine 6 starts using the side wall portion 41B of the outer shell shield starting base 4 as a starting pit.

  The positions, sizes, etc. of the circumferential shield start base 3 and the outer shield start base 4 can be changed as appropriate according to conditions such as the outer diameter of the main shield tunnel 1. Furthermore, the configuration of the circumferential shield machine 5, the number of outer shell shield machines, and the configuration of the outer diameter are not limited to the present embodiment, and can be arbitrarily determined.

  In this embodiment, it is an application example when constructing a road tunnel with a large cross section, but it can be widely applied to constructing tunnels of various scales, uses, and forms having the above-mentioned underground cavity. In addition, various design changes can be made in accordance with the size and form of the underground cavity in the tunnel to be constructed and in consideration of various conditions such as the surrounding environment.

  Moreover, the range of the ground improvement part by the freezing method etc. which are integrally formed between adjacent outer shell shield tunnels 2, the form and the construction method, and other details of each process are within the scope not departing from the gist of the present invention. In this case, an optimum auxiliary method may be adopted as necessary.

  Furthermore, although the circumferential shield machine 5 of the present embodiment is an open type, it is also possible to use a rectangular sealed circumferential shield machine and a corresponding circumferential segment.

  In addition, it is possible to appropriately replace the components in the above-described embodiments with known components without departing from the spirit of the present invention.

1 main shield tunnel 1A start base 1a outer peripheral surface 2 outer shell shield tunnel 2A first straight part 2B curved part 2C second straight part 3 circumferential shield start base (circumferential shield start part)
4 Outer Shield Start Base (Outer Shield Start)
5 Circumferential shield machine 6 Outer shell shield machine 10 Underground cavity part 11 Multi-segment segment 20 Outer shell body 41 Circumferential segment 41B, 41C Side wall part 51A, 51B Guide ring X Tunnel axial direction

Claims (2)

When constructing underground cavities by excavating underground, the outer shield tunnels are constructed by arranging a plurality of outer shield tunnels outside the planned excavation position of the underground cavities. A construction method of a large-section tunnel that constructs an outer shell body that surrounds the planned excavation position and excavates the inside of the outer shell body,
The process of constructing the main line shield tunnel,
A process of constructing a circumferential shield starting portion obtained by cutting out a part of the circumferential direction of the main shield tunnel;
A step of constructing a ring-shaped outer shell shield starting portion by excavating in a circumferential direction along an outer peripheral surface of the main shield tunnel by a circumferential shield machine from the circumferential shield starting portion;
Starting a shell shield machine from a side wall portion having a plane perpendicular to the tunnel axis direction of the main shield tunnel in the shell shield starting portion, and constructing a plurality of shell shield tunnels;
Have
The outer shell shield tunnel starts from the outer shell shield starting portion in parallel with the main shield tunnel, and gradually digs in a direction away from the main shield tunnel in the radial direction as it digs. The construction method of the large section tunnel characterized by being done.   The construction of a large section tunnel according to claim 1, wherein a plurality of said outer shield machines are arranged along a circumferential direction in said outer shield starting part, and these outer shell shield machines are dug simultaneously. Method.

Images