JPH0791948B2 - Backflow prevention plate for shield machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a shield machine, in which a backfill material injected into a tail void flows backward to the outer circumference of the shield and is solidified on the outer surface of the shield body, resulting in obstacles to the excavation. The present invention relates to a backflow prevention plate for preventing the backflow.

[Conventional technology]

The backflow prevention plate used conventionally is as shown in FIGS. The backflow prevention plate 8 shown in these drawings is made of spring steel, and its base end portion is a tail seal member 5 and an inner protection plate 6, and an outer protection plate 7 of a tail seal 4 composed of an outer protection plate 7 and a tail of a width dimension X. It is sandwiched between the seal mounting hardware 3 and the tail seal 4 and is attached to the inside of the tail skin plate 1 of the shield body so as to be sequentially connected in the circumferential direction. By making contact with the excavation tunnel wall surface 10 as shown in FIG. 5, backflow of the backfill material 11 injected into the gap (tail void) between the segment 2 and the excavation tunnel wall surface 10 to the shield body side is prevented.

As shown in FIG. 7, the width of the portion of the backflow prevention plate 8 that is sandwiched between the tail seal mounting hardware 3 and the outer protection plate 7 is the X dimension, but the width becomes wider from the part that is farther than that, and the tip portion 9
The Y dimension is near. Then, the portions extending in the width direction are attached so as to overlap with each other. The tip portion 9 of the backflow prevention plate 8 in contact with the wall surface 10 of the excavation tunnel is
It is usually formed in a linear shape as shown in FIG.

[Problems to be Solved by the Invention]

The backflow prevention plate 8 used conventionally is the wall surface of the excavation tunnel.
Since the tip portion 9 in contact with 10 is linear, the following problems occur.

(1) In the normal circular shield tunnel (Fig. 10) and double-sided circular tunnels a and b of the double shield tunnel (Fig. 11) having a cocoon-shaped cross section, the tip 9 of the backflow prevention plate 8 is shown in Fig. 8. As shown, it becomes inscribed in the arc of the excavation tunnel wall surface 10,
At the reverse arc portions c and d that connect the circular portions a and b on both sides of the double shield tunnel (Fig. 11), the tip portion 9 of the backflow prevention plate 8 is at the 9th position.
As shown in the figure, it is in a state of circumscribing the arc of the wall surface 10 of the excavation tunnel. In any case, since the tip portion 9 of the backflow prevention plate 8 is hard to fit into the excavation tunnel wall surface 10, a gap is generated between the backflow prevention plate 8 and the backflow prevention plate 8 adjacent to each other. Difficult to adhere,
It is not possible to exert a sufficient sealing function against the osmotic pressure of the backfill material.

(2) When the tip portion 9 of the backflow prevention plate 8 is inscribed in the arc of the excavation tunnel wall surface 10 as shown in FIG. 8, the excavation tunnel wall surface 10 is scratched at the corner portion a of the tip portion 9 and the scratch is caused. The back-filling material easily leaks from the open part. Further, as shown in FIG. 9, when the front end portion of the backflow prevention plate 8 circumscribes the arc of the excavation tunnel wall surface 10, the backflow prevention plate 8 receives a bending force due to the injection pressure of the backfill material. The stress concentrates near the center of the cracks, and cracks occur, or the backflow prevention plates 8 adjacent to each other are easily damaged at the corners B of the protruding corners.

In view of the above points, the present invention has a shape in which the tip portion of the backflow prevention plate is easily adapted to the wall surface of the excavation tunnel,
The purpose is to improve the adhesion between the backflow prevention plate and the excavation tunnel wall surface and the adjacent backflow prevention plates to improve the sealing function against the backflow of the backfill material, and to prevent the backflow prevention plate and the excavation tunnel wall surface from being damaged. And

[Means for Solving the Problems]

In order to achieve the above object, in the invention according to the first aspect, the tip end portion of the backflow preventing plate inscribed in the arc of the wall surface of the excavation tunnel is formed into a convex arc shape along the wall surface of the excavation tunnel.

Further, according to the second aspect of the present invention, the front end portion of the backflow prevention plate circumscribing the arc of the wall surface of the excavation tunnel is formed into a concave arc shape along the wall surface of the excavation tunnel.

[Action]

When the tip of the backflow prevention plate inscribes the arc of the wall surface of the excavation tunnel obliquely, the cut surface of the wall surface of the excavation tunnel formed by the plane including the backflow prevention plate becomes elliptical. Therefore, by making the tip end portion of the backflow prevention plate into a substantially arc shape (convex shape when viewed from the base end side) corresponding to this cut shape, the tip end portion of the backflow prevention plate fits well with the excavation tunnel wall surface, The clearance between them can be made as small as possible, and the overlapping parts of adjacent backflow prevention plates can be easily contacted.
The corners at the tip of the backflow prevention plate are not scratched by the wall surface of the excavation tunnel and scratch the wall surface.

When the tip of the backflow prevention plate circumscribes the arc of the wall of the excavation tunnel diagonally, the cut surface of the wall of the excavation tunnel formed by the plane including the backflow prevention plate becomes an ellipse in the opposite direction to the above, so the tip of the backflow prevention plate By making the part into a substantially arc shape corresponding to this cut shape (concave when viewed from the base end side), the tip of the backflow prevention plate fits well with the wall surface of the excavation tunnel, and the gap between them can be made as small as possible. The overlapping portions of the adjacent backflow prevention plates will also easily adhere, and the adjacent backflow prevention plates will be damaged or damaged at the tip corners of the backflow prevention plates. The stress is not concentrated near the center.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

As shown in FIGS. 5 and 6, the backflow prevention plate 8 of the present invention has its base end portion sandwiched between the outer protection plate 7 of the tail seal 4 and the tail seal mounting hardware 3, and together with the tail seal 4. This is the same as the conventional backflow prevention plate (FIG. 7) in that it is attached to the inside of the tail skin plate 1 of the shield body in a circumferentially continuous manner.

In the following description, of the backflow prevention plate 8, the backflow will be performed as in the normal circular shield tunnel (Fig. 10) and the double-sided circular portions a and b of the double shield tunnel (Fig. 11) having a cocoon-shaped cross section. The one used at the position where the tip of the prevention plate inscribes the arc of the wall surface 10 of the excavation tunnel is called the inversion backflow prevention plate 8a, and the circular portions a and b on both sides of the double shield tunnel (Fig. 11).
Like the reverse circular arc portions c and d connecting the two, the one used at the position where the tip of the backflow prevention plate circumscribes the circular arc of the excavation tunnel wall surface 10 is referred to as the external circulation backflow prevention plate 8b.

FIG. 1 is a developed plan view of an inscribed backflow prevention plate 8a according to the present invention, and FIG. 2 is a view of the contact state between the inscribed backflow prevention plate 8a and the excavation tunnel wall surface 10 as seen from the tunnel axis direction.
As shown in both figures, the tip portion 9a inscribed in the arc of the excavation tunnel wall surface 10 of the inscribed backflow prevention plate 8a has a substantially arcuate shape that is convex when viewed from the base end side, and during normal excavation of a shield machine. ,
The tip portion 9a is arranged along the excavation tunnel wall surface 10. By doing so, the tip 9a can be brought into line or surface contact with the excavation tunnel wall surface 10, so that the tip portion 9a is in contact with the excavation tunnel wall surface 10 as compared with the case where the tip portion 9 is linear as shown in FIG. Also, the overlapping portions of the adjacent backflow prevention plates are easily brought into close contact with each other. Further, by making the tip 9a into a convex, substantially arcuate shape, it is possible to prevent the corners of the tip 9a from being caught by the excavation tunnel wall surface 10 and damaging the wall surface. In order to prevent mutual damage of the backflow prevention plates and damage to the wall surface of the excavation tunnel, the corners of the backflow prevention plate 8a may be rounded as shown.

FIG. 3 is a developed plan view of the external backflow prevention plate 8b according to the present invention, and FIG. 4 is a view of the contact state between the external backflow prevention plate 8b and the excavation tunnel wall surface 10 as seen from the tunnel axis direction.
As shown in both figures, the tip portion 9b circumscribing the arc of the excavation tunnel wall surface 10 of the circumscribing backflow prevention plate 8b has a substantially arcuate shape that is concave when viewed from the base end, and when the shield machine is normally excavated, the tip portion 9b should be along the excavation tunnel wall 10. By doing so, the tip portion 9b can be brought into line or surface contact with the excavation tunnel wall surface 10 in the same manner as the inscribed backflow prevention plate 8a, so that the tip portion 9 is linear as shown in FIG. As compared with the above case, it becomes easier to make close contact with the excavation tunnel wall surface 10 and between the overlapping portions of the adjacent backflow prevention plates. Also, it is possible to prevent the corners of the tip portion 9b from jumping up so that adjacent backflow prevention plates are mutually damaged, and the tip portion 9b receives a bending force and stress concentrates near the center to prevent cracking. it can. Also in this case, the corners of the backflow prevention plate 8b may be rounded as illustrated.

〔The invention's effect〕

 The effects of the present invention can be summarized as follows.

(I) Both of the internal backflow prevention plate and the external connection backflow prevention plate are easier to adapt the tip of the backflow prevention plate to the wall surface of the excavation tunnel than the conventional backflow prevention plate, and the overlapping portions of the adjacent backflow prevention plates are in close contact Since it is easy to do so, it can be expected to improve the sealing function to prevent backflow of the backfill material.

(Ii) In the internal backflow prevention plate, it is possible to prevent the corners of the backflow prevention plate from being caught on the wall surface of the excavation tunnel and damaging the wall surface as in the conventional case.

(Iii) In the external backflow prevention plate, it is possible to prevent the adjacent backflow prevention plates from being damaged by each other at the corners of the backflow prevention plate tip portion, which are different from the conventional ones.
The stress concentration at the tip of the backflow prevention plate can be reduced.

[Brief description of drawings]

FIG. 1 is a developed plan view of an inscribed backflow prevention plate according to the present invention,
2 is a view of the contact state between the backflow prevention plate for inscribing and the wall surface of the excavation tunnel as seen from the axial direction of the tunnel, FIG. 3 is a development view of the backflow prevention plate for inscribing according to the present invention, and FIG. FIG. 5 is a view of the contact state between the backflow prevention plate and the wall surface of the excavation tunnel as seen from the direction of the tunnel axis, FIG. 5 is a side cross-sectional view showing the installation state of the backflow prevention plate, and FIG. Sectional view, FIG. 7 is a developed plan view of the conventional backflow prevention plate, and FIGS. 8 and 9 are views of the contact state between the conventional backflow prevention plate and the wall surface of the excavation tunnel viewed from the tunnel axis direction, FIG. FIG. 11 is a sectional view of the tunnel. DESCRIPTION OF SYMBOLS 1 ... Tail skin plate, 2 ... Segment, 3 ... Tail seal fitting, 4 ... Tail seal, 8 ... Backflow prevention plate, 8a ... Inflow backflow prevention plate, 8b ... Outer connection backflow prevention plate, 9
… Tip of backflow prevention plate, 9a… Tip of backflow prevention plate for internal contact, 9b… Tip of backflow prevention plate for external connection, 10… Excavation tunnel wall surface, 11… Backfill material.

Claims (2)

[Claims] 1. A backflow prevention, which is attached to the inside of a tail skin plate of the shield body in a circumferential direction in a sequential manner together with the tail seal to prevent backflow of the backfill material injected into the tail void toward the outer circumference side of the shield body. A backflow prevention plate for a shield machine, wherein the tip of the plate inscribed in the arc of the wall surface of the excavation tunnel has a substantially arcuate shape that is convex along the wall surface of the excavation tunnel. 2. A backflow prevention plate, which is attached to the inside of a tail skin plate of the shield body together with the tail seal in a circumferential direction in order to prevent backflow of the backfill material injected with tail voids to the outer circumference side of the shield body. A backflow prevention plate for a shield machine, wherein a tip end portion circumscribing an arc of the wall surface of the excavating tunnel has a concave arc shape along the wall surface of the excavating tunnel.