JP6624440B2 - Freezing method - Google Patents

Description

  The present invention, for example, when constructing a large-section underground cavity such as a branch junction of a road tunnel, freezes the ground between a plurality of outer shell shield tunnels arranged outside the planned excavation position and excavates. It is related to the freezing method.

  Conventionally, when constructing underground cavities with large cross sections such as branch junctions of road tunnels, construct multiple shell shield tunnels arranged at predetermined intervals outside the planned location of underground cavities, There is known a method of constructing a shield roof precedent surrounding a planned construction position (for example, see Patent Documents 1 to 3).

  For example, in Patent Literature 1, a circumferential shield starting base in which a part of the main line shield tunnel is cut out is constructed, and a circumferential shield machine excavates from the circumferential shield starting base along the outer peripheral surface of the main line shield tunnel. In this way, a ring-shaped outer shield starting base will be constructed, the outer shield machine will be launched from the side wall of the outer shield starting base, and a plurality of outer shield tunnels will be constructed. Furthermore, the ground between the plurality of outer shell shield tunnels is connected by freezing with a freezing pipe and excavating to construct an outer shell surrounding the planned excavation position.

JP 2014-43737 A JP-A-2005-129411 JP 2007-217911 A

  By the way, conventionally, when freezing the ground between a plurality of outer shield tunnels, the freezing tube is arranged radially from the outer shield tunnel to freeze the ground. In this method, it is necessary to arrange a large number of freezing pipes, which may lead to an increase in construction cost and a prolonged construction period. For this reason, it has been required to arrange the cryotube more rationally.

  The present invention has been made in view of the above, and an object of the present invention is to provide a freezing method in which a freezing tube is rationally arranged.

  In order to solve the above-described problems and achieve the object, a freezing method according to the present invention is configured such that, when the interval between a plurality of tunnels is widened along the axial direction of the tunnel, a freezing tube is arranged between the tunnels. A freezing method for freezing the ground between the tunnels and excavating, wherein on the side where the interval between the tunnels is narrow, the freeze pipe is arranged along the axial direction, and the interval between the tunnels is wide. On the side, the freezing tube is arranged in a direction crossing the axial direction.

  Further, in another freezing method according to the present invention, in the above invention, the freezing tube arranged in a direction intersecting with the axial direction is shorter than the freezing tube arranged along the axial direction. It is characterized.

  Another freezing method according to the present invention is characterized in that, in the above invention, the freezing pipe is arranged along the axial direction in parallel with the construction of the plurality of tunnels.

  Further, another freezing method according to the present invention is the above-mentioned invention, wherein in the above-mentioned invention, a sheath tube having a larger diameter than the freezing tube arranged along the axial direction is arranged along the axial direction, and the freezing is performed inside the sheath tube. A tube is arranged, and a filler is filled around the freezing tube.

  According to the present invention, it is possible to realize a freezing method in which freezing tubes are rationally arranged.

FIG. 1 is a schematic explanatory view of a construction method of a branch junction. FIG. 2 is a schematic explanatory view of a construction method of a branch junction. FIG. 3 is a cross-sectional view of the branch junction. FIG. 4 is a diagram illustrating a procedure of a construction method of the branch junction. FIG. 5 is a schematic explanatory view of the freezing method. FIG. 6 is a schematic explanatory view of the freezing method. FIG. 7 is a schematic explanatory view of the freezing method.

  Hereinafter, an embodiment of a freezing method according to the present invention will be described in detail with reference to the drawings, taking an example of a branching junction of a road tunnel constructed by a shield method. The present invention is not limited by the embodiment.

(Construction method of underground cavity)
First, a method of constructing an underground cavity including the freezing method according to the present invention will be described.

  1 to 3 are schematic explanatory diagrams of a method of constructing a branch junction (underground cavity). In this construction method, a plurality of outer shell shield tunnels 18 are arranged in advance using a small-diameter outer shell shield machine 16 outside the planned excavation position of the branch junction 14 including the main line shield tunnel 10 and the lamp shield tunnel 12. The outer shell body 20 surrounding the planned excavation position of the branching and joining portion 14 is constructed by the outer shell shield tunnel 18 by excavating the ground inside the outer shell body 20 and the branching and joining portion is formed. 14 is constructed.

  More specifically, first, as shown in FIG. 4A, the main line shield tunnel 10 is constructed while the ground is stably supported by a conventional shield method and the water blocking property is secured. Similarly, a not-shown lamp shield tunnel 12 is constructed next to the main line shield tunnel 10 by a conventional shield method. Subsequently, a large-diameter outer periphery of the main line shield tunnel 10 which is a rear end portion (start end portion) of the branch junction 14 to be constructed in the axial direction (a direction parallel to the tunnel axis direction in which the main line shield tunnel 10 extends) is provided. The underground starting base structure 22 of the present invention is constructed. The underground starting base structure 22 is a base for starting the small-diameter outer shell shield machine 16 that excavates the outer shell shield tunnel 18 forming the outer shell body 20 of the branching junction 14. In the present embodiment, it is assumed that the diameter of the main line shield tunnel 10 is, for example, about 16 m, the diameter of the lamp shield tunnel 12 is, for example, about 11 m, and the diameter of the branching junction 14 is about 32 m.

  Next, as shown in FIG. 4B, the outer shell shield machine 16 is started from the underground starting base structure 22, and a plurality of small diameters (for example, around the outside of the branch junction 14 to be constructed along the axial direction thereof) The outer shield tunnels 18 (about 4 m in diameter) are arranged at predetermined intervals.

  Next, as shown in FIG. 4 (3), the ground between the outer shell shield tunnels 18 is frozen and excavated by the freezing method according to the present invention, and a main body lining wall 24 is formed in the excavated area. Furthermore, the outer shell 20 is constructed by forming joint walls (not shown) at both ends of the main body lining wall 24. Then, as shown in FIG. 4D, the ground in an area surrounded by the outer shell body 20 is excavated to construct the branching junction 14. In this way, a branching junction 14 for a road tunnel as shown in FIG. 4 (5) is completed.

(Freezing method)
Next, a freezing method according to the present invention, which is used in the above-described method of constructing an underground cavity, will be described.

  5 to 7 show schematic explanatory views of the freezing method. In this freezing method, as shown in FIG. 5, when the interval between the outer shield tunnels 18 is widened along the axial direction of the outer shield tunnel 18, a horizontal freezing tube is used as a freezing tube between the outer shield tunnels 18. 26 and a radiation freezing tube 28 are arranged to freeze the ground and excavate. A frozen liquid such as calcium chloride is circulated in the horizontal freezing tube 26 and the radiation freezing tube 28 to form frozen soil. More specifically, in this freezing method, the horizontal freezing tube 26 is arranged along the axial direction of the outer shell shield tunnel 18 on the side where the distance between the outer shell shield tunnels 18 is narrow, and On the side where the interval is wide, the radiation freezing tube 28 is arranged in a direction intersecting the axial direction of the outer shield tunnel 18. FIG. 5 shows only two outer shield tunnels 18 of the plurality of outer shield tunnels 18 and the horizontal freezing tube 26 and the radial freezing tube 28 disposed therebetween.

  As shown in FIG. 6, in a cross section corresponding to the line AA in FIG. 5, horizontal freezing tubes 26 are arranged above and below the middle of the outer shell shield tunnel 18 adjacent to each other. The horizontal freezing tube 26 is, for example, a sheath tube having a diameter of 450 mm is constructed in a predetermined length along the axial direction by a small-diameter propulsion method, a freezing tube having a diameter of 150 mm is arranged therein, and a mortar or the like is provided around the freezing tube. Is filled with the filler. Since the horizontal freezing tube 26 is longer than the radiation freezing tube 28, it is preferable that the diameter of the horizontal freezing tube 26 is larger than that of the radiation freezing tube 28. A freezing tube is also arranged inside the outer shell shield tunnel 18 along the outer shell shield tunnel 18.

  As shown in FIG. 7, when viewing FIG. 5 from the direction of arrow B, radiation freezing tubes 28 are arranged vertically from each outer shield tunnel 18 to the next outer shield tunnel 18. The radiation freezing tube 28 is, for example, a freezing tube having a diameter of 90 mm. Since the radiation freezing tube 28 is shorter than the horizontal freezing tube 26, it may be smaller in diameter than the horizontal freezing tube 26.

  In this freezing method, by arranging the horizontal freezing tubes 26 on the side where the space between the outer shield tunnels 18 is narrow, the number of freezing tubes can be reduced as compared with the conventional method. Specifically, the number of the freezing tubes can be reduced to about half in the freezing method according to the present invention, as compared with the conventional method in which all the freezing tubes are radially arranged. Therefore, it is possible to reduce the construction cost and the construction period. On the other hand, on the side where the distance between the outer shell shield tunnels 18 is wide, the radiant freezing tube 28 is provided to form frozen soil having a sufficient thickness and prevent the horizontal freezing tube 26 from becoming too long. This is because, if the horizontal freezing tube 26 becomes longer, the time required for freezing the ground around the horizontal freezing tube 26 becomes longer, which may lead to a longer construction period. Therefore, this freezing method is a freezing method in which freezing tubes are rationally arranged.

  When the radiation freezing tube 28 is installed radially from the outer shield tunnel 18, the inner space is variously used during the excavation of the outer shield tunnel 18. Although it is difficult to perform the work, the horizontal freezing pipe 26 installed in the middle of each outer shield tunnel 18 can be arranged in parallel with the excavation of the outer shield tunnel 18. The construction period can be shortened.

  The ratio between the section in which the horizontal freezing pipe 26 is disposed and the section in which the radiation freezing pipe 28 is disposed is determined by appropriately determining an optimum ratio depending on construction conditions such as the length and diameter of each tunnel and the construction period. The longer the section in which the freezing tube 26 is provided, the better. For example, if the section in which the horizontal freezing tube 26 is provided and the section in which the radiation freezing tube 28 is provided have the same length, it is possible to greatly shorten the construction period.

  Further, in this freezing method, since the horizontal freezing pipe 26 can be arranged from the underground starting base structure 22, the horizontal freezing pipe 26 can be arranged without waiting for the completion of the outer shell shield tunnel 18. Therefore, this freezing method is an advantageous freezing method for shortening the construction period.

  As described above, the freezing method according to the present invention, for example, when constructing a large-section underground cavity such as a branch junction of a road tunnel, between a plurality of outer shell shield tunnels arranged outside the planned excavation position It is useful when excavating the ground by freezing it, and is particularly suitable for providing a freezing method in which frozen pipes are rationally arranged.

10 Main line shield tunnel 12 Ramp shield tunnel 14 Branch junction (underground cavity)
16 outer shell shield machine 18 outer shell shield tunnel 20 outer shell body 22 underground starting base structure 24 main body lining wall 26 horizontal freezing tube 28 radiation freezing tube

Claims (4)

When the interval between a plurality of tunnels is widened along the axial direction of the tunnel, a freezing method in which a freezing tube is arranged between the tunnels to freeze the ground between the tunnels and excavate,
On the side where the interval between the tunnels is narrow, the cryotube is arranged along the axial direction,
A freezing method, wherein the freezing tube is arranged in a direction intersecting with the axial direction on a side where a distance between the tunnels is wide.   2. The freezing method according to claim 1, wherein the freezing tube arranged in a direction intersecting with the axial direction is shorter than the freezing tube arranged along the axial direction. 3.   The freezing method according to claim 1, wherein the freezing pipe is arranged along the axial direction in parallel with the construction of the plurality of tunnels. Arranging a sheath tube having a larger diameter than the freezing tube arranged along the axial direction along the axial direction,
Placing the cryotube within the sheath,
The freezing method according to claim 1, wherein a filler is filled around the freezing tube.

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