JP7133459B2 - Floating prevention structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to a surfacing prevention structure used during initial excavation of a shield tunnel.

During the initial excavation of a shield tunnel, generally, reaction force is taken from a reaction force receiving structure formed behind the shield machine.
As such a reaction force receiving structure, for example, as shown in Patent Document 1, there is a structure formed by a temporary assembly segment assembled at the rear of the shield machine.
In addition, Patent Document 2 discloses an initial excavation method in which a cylindrical member for inserting a shield machine is provided in the wellhead, and reaction force is taken from a temporary assembly segment arranged behind the shield machine in the cylindrical diameter member. there is A sealing material is interposed between the inner surface of the cylindrical member and the outer surface of the shield machine.
Here, if the thrust of the propulsion jack acts on the temporarily assembled segment during the initial excavation, there is a risk that the temporarily assembled segment, which is lighter than the shield machine, may float. If the temporary assembly segment floats up, the excavation direction by the shield machine is shifted. Therefore, in the conventional reaction force receiving structure, a wire rod (e.g., PC steel wire) whose both ends are fixed by anchors or the like is provided around the outer surface of the upper half of the temporary assembly segment, thereby preventing the temporary assembly segment from floating. may prevent it.
The weight of the front portion of the shield machine in the traveling direction is larger than that of the rear portion. Therefore, there is a risk that the rear portion of the shield machine will float up during the initial excavation performed in the air. On the other hand, for a shield machine that moves along with excavation, it is not possible to fix a wire rod similar to the temporary assembly segment around the outer peripheral surface.
According to the initial excavation method of Patent Document 2, although it is possible to maintain the accuracy of the excavation direction of the shield machine with the cylindrical member, in the construction of a large-section tunnel, a cylindrical member for inserting the shield machine is installed. To do so requires a lot of effort and money.

Japanese Patent Application Laid-Open No. 2001-020693 JP-A-08-021183

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems, and to propose a surfacing prevention structure capable of performing initial excavation with high accuracy with a simple configuration.

A first levitation prevention structure of the present invention for solving the above problems comprises a plurality of arch-shaped cross beams arranged along the upper surface of the shield machine in the excavation direction of the shield machine, and the arch-shaped cross beams. Vertical girders connecting each other, a temporary assembly segment assembled behind the shield machine, a support stand on which the temporary assembly segment is placed, and a lateral deviation prevention material that supports the side surface of the temporary assembly segment. I have. The end of the arch-shaped cross beam is fixed to a support member extending from the front surface of the earth retaining wall formed at the planned tunnel entrance or to a support member provided on the side wall formed on the side of the shield machine. It is Further, the temporarily assembled segment is fixed to the support frame via a jig inserted through the injection hole. Further, the lateral deviation prevention member can advance and retreat in a direction intersecting with the excavation direction of the shield machine.
According to this anti-floating structure, when the shield machine floats, the arch-shaped cross beams can suppress a large deviation. In addition, since the arched cross beams are fixed to earth retaining walls, side walls, or the like, they do not require supports erected from the bottom slab (ground) or the like. Therefore, even when constructing a large-section tunnel, a relatively simple configuration can be achieved without requiring a large-scale support structure. By forming a scaffolding on the arch-shaped cross girder (on the anti-floating structure), it can be used as a scaffolding for pithead treatment. In addition, if a gap of a predetermined size is provided between the outer peripheral surface of the shield machine and the lower surface of the arched cross beam, or if rollers or the like are interposed, the arched cross girder can be removed when the shield machine excavates. does not interfere with excavation due to contact with the shield machine. When the rollers are installed, it is desirable that they can follow unevenness of the outer surface of the shielding machine.

Further , according to the floating prevention structure, the temporarily assembled segment is fixed to the support frame via the jig, so that the temporarily assembled segment is prevented from floating. Further, the lateral deviation preventing member prevents the temporarily assembled segment from shifting in the lateral direction, and also prevents the temporarily assembled segment from deforming into an elliptical shape. As described above, according to the present invention, since the displacement of the temporarily assembled segments is suppressed during the initial excavation of the shield tunnel, the displacement of the shield machine caused by the displacement of the temporarily assembled segments is also suppressed.

According to the levitation prevention structure of the present invention, due to the simple configuration of the plurality of arch-shaped horizontal girders and vertical girders, there is a gap between the shield machine and the shield machine during normal times, so that excavation is not hindered, and the shield When the machine floats, it comes into contact with the shield machine to suppress a large deviation, so it is possible to perform the initial excavation of the shield tunnel with high accuracy.

1 is a plan view of a floating prevention structure according to an embodiment of the present invention; FIG. It is a front view of a floating prevention structure. (a) and (b) are side views showing a part of the floating prevention structure. FIG. 4 is a cross-sectional view showing part of the floating prevention structure;

In this embodiment, a floating prevention structure 1 for preventing floating of a shield machine 10 disposed in the air during initial excavation of a shield tunnel for a road tunnel will be described.
In this embodiment, as shown in FIG. 1, a tunnel is excavated using a shield machine 10 assembled in the air. A retaining wall W1 is formed at a planned tunnel entrance portion, and a reaction slab W2 is formed so as to face the retaining wall W1 with the shield machine 10 interposed therebetween. Further, a side wall W3 is formed on one side of the shield machine 10, and a crane stand S for a portal crane is formed on the other side. Note that the structure of the tunnel portal is not limited. For example, the crane platform S may be formed as required. Also, the initial excavation may start from within a shaft surrounded by an earth retaining wall.
As shown in FIGS. 1 and 2, the anti-floating structure 1 includes an arched cross beam 2, a vertical beam 3, a support member 4, a scaffolding 5, and temporary assembly segments 6. As shown in FIG. In addition, illustration of the scaffolding 5 is omitted in FIG.

The arch-shaped crossbeam 2 is a steel material arranged along the upper surface of the shield machine 10 . In this embodiment, three arch-shaped horizontal girders 2 are arranged side by side at intervals in the excavation direction of the shield machine 10 . In addition, the number of the arch-shaped crossbeams 2 is not limited. Further, in the present embodiment, the arch-shaped horizontal beams 2 are made of H-shaped steel, but the material of which the arch-shaped horizontal beams 2 are made is not limited, and may be, for example, channel steel or L-shaped steel. There may be. The arch-shaped transverse beam 2 has an arch-shaped arch portion 21 and left and right straight portions 22 , 22 extending from both ends of the arch portion 21 .
The arch portion 21 has an arc shape with a central angle of about 60° to 90°. The size of the central angle of the arch portion 21 is not limited. The lower surface of the arch portion 21 (arch-shaped cross beam 2) is parallel to the outer peripheral surface of the upper portion of the shield machine 10. As shown in FIG. A gap of a predetermined size is provided between the lower surface of the arch portion 21 (arch-shaped horizontal beam 2) and the outer peripheral surface of the shield machine 10. As shown in FIG. Although the size of the gap between the arch-shaped cross beam 2 and the shield machine 10 is not limited, it is set to 10 mm to 20 mm in this embodiment.
The straight portion 22 is made of a straight steel material and is integrally fixed to the end portion of the arch portion 21 . The tip of the straight portion 22 (the lower end of the arch-shaped horizontal beam 2) is fixed to the support member 4. As shown in FIG.

As shown in FIGS. 3(a) and 3(b), the vertical beams 3 are made of straight steel material with a length equal to or less than the space between the webs of the adjacent arched horizontal beams 2. interposed in between. The vertical girders 3 connect the arch-shaped horizontal girders 2 adjacent to each other in the excavation direction of the shield machine 10. - 特許庁In this embodiment, the arch portions 21 of the arch-shaped horizontal beams 2 are connected by the vertical beams 3 . A plurality of longitudinal girders 3 are arranged at predetermined intervals in the longitudinal direction of the arch-shaped transverse girders 2 . The number and arrangement (arrangement pitch) of the stringers 3 are not limited. Further, the vertical beams 3 do not necessarily have to be interposed between the arched horizontal beams 2 . For example, as the longitudinal beams 3, a steel material having a length longer than the interval between the horizontal arch beams 2 may be used to connect the upper or lower surfaces of the horizontal arch beams 2. When the vertical beam 3 is fixed to the lower surface of the arch-shaped horizontal beam 2, a gap is provided between the lower surface of the vertical beam 3 and the outer surface of the shield machine 10. - 特許庁

The support member 4 supports the arched cross beam 2 and is formed by combining steel materials. As shown in FIGS. 1 and 2, the support members 4 are formed on the left and right sides of the shield machine 10, respectively. One supporting member 4 (first supporting member 41) extends along the axial direction of the shield machine 10 from the front surface of the earth retaining wall W1 formed at the expected tunnel entrance portion, as shown in FIG. 3(a). It is The tip of the first support member 41 (the end opposite to the retaining wall W1) is supported by a bracket 43 fixed to a frame formed on the side of the shield machine 10. As shown in FIG. The other supporting member 4 (second supporting member 42) protrudes from a side wall W3 formed on the side of the shielding machine 10, as shown in FIG. 3(b). The second support member 42 includes upper and lower first members 44 fixed to the side wall W3, a second member 45 that connects the upper and lower first members 44, and a second member 45 that connects the front and rear adjacent first members 44 to each other. It is a pedestal formed by combining the three members 46 . One end of the arch-shaped cross beam 2 (the tip of the straight portion 22) is fixed to the upper surface of the first support member 41, and the other end of the arch-shaped cross beam 2 (the tip of the straight portion 22) is It is fixed to the upper surface of the second support member 42 . In addition, the structure of the support member 4 is not limited. For example, it may be provided via a pillar erected on the bottom plate B.

The scaffolding 5 is formed on the arched crossbeam 2, as shown in FIG. The scaffolding 5 includes a support frame 51 fixed to the upper surface of the arch-shaped horizontal beam 2, a scaffold board 52 laid on the upper surface of the support frame 51, and a handrail 53. The support frame 51 is formed by combining steel materials. The scaffolding 5 of this embodiment has a flat field 54 formed at the top of the arch-shaped horizontal girder 2 and a plurality of steps 55 formed on the left and right sides of the flat field 54 in a cross-sectional view. Adjacent small steps 55 can come and go by stairs 56. - 特許庁Note that the number of steps of the steps 55 of the scaffolding 5 and the size of the steps are not limited. Further, the scaffolding 5 includes an overhang 57 extending forward (toward the earth retaining wall W1) from the flat field 54, as shown in FIGS. 3(a) and 3(b).

The temporary assembly segment 6 is assembled behind the shield machine 10 as shown in FIG. The temporary assembly segment 6 is placed on a support stand 7 formed on the bottom plate B, as shown in FIG. The temporary assembly segment 6 of this embodiment is fixed to the support base 7 via a jig 71 inserted through an injection hole (not shown) of the backfilling material. In this embodiment, a PC steel bar is used as the jig 71 . The material forming the jig 71 is not limited, and may be, for example, PC steel wire or bolt. The support frame 7 is constructed by combining steel materials. Further, the provisional assembly segment 6 may have more injection holes (insertion holes) depending on the mounting locations of the jigs 71 . A pair of triangular protrusions 72 are formed on the upper surface of the support frame 7 with a space therebetween. By forming the pair of protrusions 72 , a recess 73 into which the lower part of the circular temporary assembly segment 6 can be inserted is formed on the upper surface of the support frame 7 . The temporary assembly segment 6 is placed on the pair of projections 72 with the lower portion inserted into the recess 73 . After that, the jig 71 is inserted into the injection hole, and the jig 71 is fixed to the convex portion 72 .
Further, the temporarily assembled segments 6 are supported at their side surfaces by lateral displacement prevention members 8 . The lateral displacement prevention member 8 is provided with a jack (not shown) and is configured to be able to advance and retreat in a direction intersecting the tunneling direction of the shield machine 10 . The lateral displacement prevention member 8 is in contact with the side surface of the temporary assembly segment 6 at the position of the height direction middle portion (spring line SL) of the temporary assembly segment 6 . Further, the lateral deviation prevention member 8 is fixed to the side wall W3 formed on the side of the temporary assembly segment 6 and the crane base S. As shown in FIG.
As the shield machine 10 excavates, the temporary assembly segment 6 assembled under the arch-shaped horizontal girder 2 behind the shield machine 10 is restrained from rising by the arch-shaped horizontal girder 2 . Since the temporary assembly segment 6 has a smaller outer diameter than the shield machine 10, a gap is formed between the arch-shaped horizontal beam 2 and the temporary assembly segment 6, but a spacer (for example, steel material) can be inserted in the gap. to prevent the temporarily assembled segment 6 from floating. Note that the structure of the spacer is not limited, and for example, a jack or the like may be used.

According to the surfacing prevention structure 1 of this embodiment, since the arched cross beam 2 is horizontally suspended above the shield machine 10, even if the rear of the shield machine 10 floats up during the initial excavation, the arched cross girder 2 A large displacement is suppressed by Therefore, it is possible to prevent the shield machine 10 from making a large deviation in the excavation direction. In addition, since a gap is formed between the shield machine 10 and the arch-shaped horizontal girder 2, when the shield machine 10 is excavated without any deviation, the shield machine 10 and the arch-shaped horizontal girder 2 does not come into contact with Therefore, the arch-shaped horizontal girder 2 does not interfere with the excavation of the shield machine 10. - 特許庁In addition, since the lower surface of the arch portion 21 (arch-shaped horizontal beam 2) is parallel to the outer peripheral surface of the upper portion of the shield machine 10, lateral displacement of the shield machine 10 can also be suppressed. In addition, since the arch-shaped horizontal girder 2 can be used as the base of the scaffolding 5 for managing the wellhead (treating water leakage from the wellhead, operating valves for injecting grout, etc.), it is possible to reduce the labor and cost of assembling a separate scaffolding. . That is, the arch-shaped horizontal beam 2 (floating prevention structure 1) functions as a tension member for suppressing the lifting of the shield machine 10, and also functions as a base of the scaffolding 5. As shown in FIG.
In addition, since the arch-shaped horizontal beams 2 are fixed to the supporting members 4 extending from the earth retaining walls W1, side walls W3, etc., it is not necessary to construct a large-scale supporting structure around the shield machine 10. - 特許庁Therefore, the anti-floating structure 1 can be formed relatively easily and inexpensively.

Moreover, since the temporary assembly segment 6 is fixed to the support stand 7 via the jig 71, it is prevented from floating. Therefore, the lifting of the rear portion of the shield machine 10 due to the lifting of the temporarily assembled segment 6 is prevented. In addition, since the lateral shift prevention member 8 is disposed on the side of the temporary assembly segment 6, the temporary assembly segment 6 is prevented from shifting in the lateral direction, and the temporary assembly segment 6 is deformed into an elliptical shape. is also prevented. Therefore, at the initial excavation of the shield tunnel, deviation of the excavation direction of the shield machine 10 is suppressed, and construction can be performed with high accuracy.

Although the embodiments according to the present invention have been described above, the present invention is not limited to the above-described embodiments, and the constituent elements described above can be changed as appropriate without departing from the scope of the present invention.
For example, in the above embodiment, the construction of a road tunnel has been described, but the purpose of use of the tunnel is not limited.
Also, the scaffold 5 may be formed as necessary.
Moreover, the temporary assembly segment 6 does not necessarily need to be fixed to the support frame 7 and may be placed on the support frame 7 without being fixed.
Further, the lateral shift prevention member 8 may be provided as required. Further, the lateral deviation prevention member 8 does not necessarily have to be movable forward and backward.
Further, the lateral deviation of the shielding machine 10 may be controlled by providing the lateral deviation prevention member 8 on the side of the shielding machine 10 as well. At this time, a gap is provided between the outer surface of the shielding machine 10 and the lateral displacement preventing member 8 so that the lateral displacement preventing member 8 is brought into contact only when the shielding device 10 is displaced. is desirable.
A wire rod (for example, PC steel wire) R, whose both ends are fixed to the bottom slab B by anchors or the like, may be provided around the outer surface of the temporary assembly segment 6 .
Also, in the above embodiment, a gap of a predetermined size is provided between the outer peripheral surface of the shield machine 10 and the lower surface of the arch-shaped horizontal beam 2, but the gap does not necessarily have to be formed. For example, between the outer peripheral surface of the shield machine 10 and the lower surface of the arch-shaped horizontal beam 2, a ball roller or a tire-type roller rotatable around an axis orthogonal to the traveling direction of the shield machine 10 may be interposed. good too. If a roller is provided between the shield machine 10 and the arch-shaped horizontal girder 2, a large displacement of the shield machine 10 can be suppressed without hindering excavation of the shield machine 10.例文帳に追加In addition, it is desirable that such a roller can follow unevenness of the outer surface of the shield machine 10 .

1 Lifting prevention structure 10 Shield machine 2 Arched horizontal girder 3 Vertical girder 4 Support member 5 Scaffolding 6 Temporary assembly segment 7 Support frame 8 Lateral deviation prevention material W1 Retaining wall W3 Side wall

Claims (3)

A plurality of arch-shaped cross girders arranged side by side in the tunneling direction of the shield machine along the upper surface of the shield machine;
a stringer that connects the arch-shaped transverse girders;
a temporary assembled segment assembled behind the shield machine;
a support frame on which the temporary assembly segment is mounted;
A levitation prevention structure comprising a lateral shift prevention member that supports the side surface of the temporary assembly segment ,
The end of the arch-shaped cross beam is fixed to a support member extending from the front surface of the earth retaining wall formed at the planned tunnel entrance or to a support member provided on the side wall formed on the side of the shield machine. being
The temporary assembly segment is fixed to the support frame via a jig inserted through the injection hole,
The surfacing prevention structure , wherein the lateral shift prevention member is movable in a direction intersecting with the excavation direction of the shield machine . The anti-floating structure according to claim 1, wherein scaffolding is formed on the arched cross beam. 3. A surfacing prevention structure according to claim 1, wherein a gap of a predetermined size is provided between the outer peripheral surface of said shield machine and the lower surface of said arch-shaped cross beam.

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