JP2002242597A - Tunnel support and tunnel support method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tunnel support which can be safely set in a tunnel excavated in the natural ground especially of a high collapsing danger, by using a shield-type TBM, and to provide a tunnel supporting method. SOLUTION: According to the tunnel supporting method, the support 1 is framed in a tail hood 10 of a shield main body such that an upper support portion 2 is smaller in curvature radius than the other support portions inclusive of both side support portions and a lower support portion in a predetermined angle range. After framing of the support, a sheet pile 21 is set at an interval between the upper support portion 2 and an upper support portion 2 of an existing support 1-1, to block the interval, and thereafter the tail hood 10 is advanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tunnel support and a tunnel support method, and more particularly to a support and a support applied in a TBM method using a shield type tunnel boring machine (hereinafter referred to as TBM). Concerning the construction method.

[0002]

2. Description of the Related Art The TBM method was originally developed for hard rock masses, and has been considered unsuitable under the conditions of Japan with complicated geology. However, TB
In recent years, a technology capable of coping with soft rock mass has been rapidly established by making M a shield type and adding various other improvements.

[0003] Although the TBM method has been variously improved so as to be able to cope with the ground conditions in Japan as described above, countermeasures against shatter zones specific to the ground in Japan are still the greatest technical problems. The form of the ground collapse in the crush zone includes a case where the ground collapses at the time of excavation by the cutter head and a case where the collapse occurs over time after passing through the cutter head.

[0004] In any case, in order to avoid tightening the TBM due to the collapsed soil, a large number of corresponding menus and agile judgment are required. Specifically, in the former case, it is unavoidable that a cavity is formed, and the excavation is continued until the TBM can be controlled, or the excavation is stopped before the TBM is tightened, and auxiliary construction methods such as ground improvement are considered. I have to choose between the two.

[0005] The latter case is a case where the ground, which was independent at the time when the cutter head passed, collapses with the passage of time due to release of stress due to excavation and supply of groundwater.
The collapsed sediment is supported on the TBM steel shell (shield body). In this case, collapsing earth and sand (rock mass) falls at the place where the steel shell comes off with the promotion of the TBM, and the work of the support works is extremely dangerous.

This will be described with reference to a conventional method shown in FIG. FIG. 8 is a sectional view in the tunnel axial direction. In the figure, the chain line A is a design excavation line, and the TBM has entered the collapse section, and the soil (rock mass) 51 has collapsed. In this case, the supporting method was conventionally performed in the following construction order.

(1) A steel support 52-1 is erected behind the tail hood 50. (2) The collapsed rock mass 51 is excavated by human power up to a manual excavation line indicated by a chain line B. (3) Driving the wooden sheet pile 53-1 sequentially with the excavation of the collapsed rock mass. (4) The sheet pile 53-1 is pressed against the group 51 of collapsed rocks by the wedge 54. At this time, the sheet pile 53-1 is in a cantilever state. (5) The rear trunk of the TBM, that is, the tail hood 50 is advanced by the interval (0.5 m) between the supports. (6) Build a new shoring 52-2 and drive a wooden sheet pile 53-2. Hereinafter, this procedure is repeated.

As described above, according to the conventional construction method, a large amount of earth and sand that has fallen on the body of the TBM during construction on a poorly grounded ground has to fall from the tail hood during assembling work. Absent. Not only does it take a great deal of effort and time to clean up the fallen earth and sand, it also increases the danger of workers when the earth and sand falls, and in many cases, the subsequent machinery of the TBM such as a belt conveyor is damaged. Work efficiency and safety are greatly reduced.

[0009]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the above technical background, and has the following objects. An object of the present invention is to provide a tunnel support and a tunnel support method capable of safely performing a support installation work in a highly collapsed ground, particularly when excavating a tunnel using a shield type TBM. It is in.

[0010]

The present invention employs the following means to achieve the above object. That is, the present invention resides in a tunnel shoring characterized in that the upper shoring portion has a smaller radius of curvature over the predetermined angle range than the other shoring portions including both sides and the lower portion. The upper shoring portion enters the inner peripheral side of the other shoring portion, and both ends are joined to both ends of the other shoring portion via joints.

The present invention also relates to a tunnel support method, wherein an upper support portion has a greater curvature in a tail hood of a shield body than another support portion including both sides and a lower portion over a predetermined angle range. Assembling the shoring with a smaller radius, after assembling the shoring, install a sheet pile between the upper shoring part and the upper shoring part of the existing shoring and close it,
Thereafter, the tail hood is moved forward.

The shoring is made of H-section steel, and the sheet piles adjacent to each other in the axial direction of the tunnel are connected on an outer peripheral flange of the shoring. Alternatively, both ends of the sheet pile are inserted and arranged between the inner and outer peripheral flanges of the support adjacent in the tunnel axis direction, and a wedge is driven between the sheet pile and the inner peripheral flange to fasten the sheet pile to the support. You may.

[0013] According to the present invention, since the upper shoring portion uses a shoring having a smaller radius of curvature than the other shoring portions, it is possible to assemble the shoring within the tail hood. It is possible to safely install the shoring work without dropping the earth and sand into the tunnel mine at the high ground. Since the radius of curvature of the other support portion is not reduced, the radius of curvature can be substantially matched with the designed excavation line, and the construction error in the collapsed ground can be minimized.

As the sheet pile, various kinds such as a wooden sheet pile and an iron sheet pile can be used. Therefore, the term “sheet pile” in the present invention means not only these wooden sheet piles and iron sheet piles,
This is a concept including general members that block between the shoring works adjacent in the tunnel axial direction.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing a shoring according to the present invention. 2 is an enlarged view of a portion surrounded by a chain line C in FIG. 1, FIG. 3 is a cross-sectional view taken along a line DD in FIG. 2, and FIG.
FIG. 7 is a sectional view taken along line EE of FIG.

The shoring 1 comprises an upper shoring portion 2 and another shoring portion 5 including both side shoring portions 3 and 3 and a lower shoring portion 4. The point that this support 1 is made of H-section steel is the same as the conventional one. According to the present invention, the upper shoring portion 2 disposed over a predetermined angle range (125 degrees in this embodiment) has a smaller radius of curvature than the other shoring portions 5, and the other shoring portions 5 (Hereinafter, the support 1 according to the present invention may be referred to as a deformed support). Specifically, the upper support section 2
The radius of curvature of the outer periphery is smaller than the radius of curvature of the inner periphery of the tail hood 10 of the TBM indicated by a chain line, so that the deformed support 1 can be assembled in the tail hood 10 as described later. It has become. Further, the outer periphery of the other shoring portion 5 substantially coincides with the design excavation line A.

The upper support portion 2 and the other support portions 5, that is, both side support portions 3, 3 are shown in FIGS.
As shown in (1), they are joined via two joint plates 6 and 7 having different sizes. One joint plate 6 has a width dimension (length in the radial direction of the shoring) substantially equal to the dimension between the flanges of the H-section steel, and is fixed to both end faces of the upper shoring portion 2. The other joint plate 7 has a width dimension substantially equal to twice the dimension between the flanges of the H-section steel, and is fixed to the end faces of the support portions 3 on both sides.

In these joint plates 6 and 7, bolt insertion holes 9 are provided.
The other joint plate 7 is provided with a rib 8 on the inner peripheral side. The upper support portion 2 and both side support portions 3 are shifted from the upper support portion 2 to the inner peripheral side, butted against the two joint plates 6 and 7, and bolts (not shown) inserted into the bolt insertion holes 9 are provided. Be tightened by. Since the joint plate 7 is reinforced by the ribs 8, the stress applied to the upper support portion 2 is completely transmitted to the side support portion 3, and functions similarly to the conventional circular support.

The side support portion 3 and the lower support portion 4 are joined as shown in FIG. This joining method is the same as the conventional one. That is, these support sections 3, 4
The joint plates 11 are fixed to the end surfaces of the joint plates 11, respectively.
The two supporting portions 3 and 4 are joined by a bolt inserted into the bolt insertion hole 12 by abutting each other.

Next, the method of the present invention using the deformed support 1 will be described. FIG. 6 is a cross-sectional view in the tunnel axial direction, showing a state in which the tail hood 10 of the TBM has been pulled out (forward movement of the rear trunk). The tail hood 10 has an effective working space length L1 (for example, about 1200 mm), of which a rear end portion has a supporting assembly space length L2 (for example, 450 mm).
Degree). The shoring work is performed as follows.

(1) The deformed support 1 is assembled in the tail hood 10. As a result of the assembly, a design space thickness C (for example, about 50 mm) is formed between the outer peripheral flange 20a of the upper support portion 2 and the inner periphery of the tail hood 10. (2) After assembling the support, the iron yagi 21 is inserted between the tail hood 10 and the assembled support 1 from the face side using the design space thickness C. Then, this iron arrow 21 is attached to the outer peripheral flange 2 of the upper supporting portion 2 in the existing deformed supporting structure 1-1.
Butt connection on 0a. Needless to say, the iron arrow 21 is installed over the entire outer periphery of the upper support section 2. Further, the connection method may be an overlapping method. (3) Next, the rear trunk is advanced, and the tail hood 10 is pulled out. Gap (about 9cm) by pulling out the tail hood 10
Is caused, a wedge 22 is driven between the iron arrow 21 and the outer peripheral flange 20a, and the iron arrow 21 is disintegrated and the soil (rock mass) 2
Press on the 3 side. Hereinafter, this procedure is repeated. When the tail hood 10 is pulled out, in order to prevent the iron arrow 21 from falling off, the iron arrow 21 may be spot-welded and fixed to the outer peripheral flange 20a of the upper support part 2 as necessary.

FIG. 7 is a sectional view in the axial direction of a tunnel showing another embodiment. This embodiment is similar to the above embodiment in that the deformed shoring 1 is assembled in the tail hood 10, but inside and outside of the upper shoring portion 2 in the assembled shoring 1 and the existing shoring 1-1. Circumferential flange 20
This embodiment is different from the above embodiment in that both ends of the wooden sheet pile 24 are inserted between a and 20b. After the insertion of the wooden sheet pile 24, the wedge 22 is inserted between the wooden sheet pile 24 and the inner peripheral flange 20b and tightened. Thereafter, the tail hood 10 is pulled out.

In both embodiments, when there is a top spring, a waterproof sheet is attached to the outer peripheral flange 20a.
In addition, every time the support 1 is assembled and the tail hood 10 is pulled out, fiber mortar is sprayed on the tunnel side wall to make the support close to the ground. The method of using deformed supports shown in each of the above embodiments is construction on collapsed ground. In the case of ordinary ground, use ordinary circular supports and assembling is performed outside the tail hood. Will be

[0024]

As described above, according to the present invention, when excavating a tunnel using a shield type TBM, the upper support portion has a smaller radius of curvature than the other support portions. Since the shoring is used, the shoring can be assembled in the tail hood, and the setting work of the shoring can be performed safely in the ground having high collapse.
Since the radius of curvature of the other support portion is not reduced, the radius of curvature can be substantially matched with the designed excavation line, and the construction error in the collapsed ground can be minimized.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a shoring work according to the present invention.

FIG. 2 is an enlarged view of a portion where a top support portion and a side portion support portion are joined together and is surrounded by a chain line C in FIG. 1;

FIG. 3 is a sectional view taken along line DD of FIG. 2;

FIG. 4 is a sectional view taken along line EE of FIG. 3;

FIG. 5 is a view showing a joint for joining a side support portion and a lower support portion.

FIG. 6 is a sectional view in the axial direction of a tunnel showing an embodiment of a tunnel support method according to the present invention.

FIG. 7 is a sectional view in the tunnel axial direction showing another embodiment of the tunnel support method.

FIG. 8 is a sectional view in the axial direction of a tunnel showing a conventional supporting method.

[Explanation of symbols]

 1: Support (deformed support) 2: Upper support part 3: Side support part 4: Lower support part 5: Other support part 6: Joint plate 7: Joint plate 8: Rib 10: Tail hood 20a: Outer peripheral flange 20b: Inner peripheral flange 21: Tetsuyagi 22: Wedge 23: Collapsed sand (rock mass) 24: Kiyaita

Claims (5)

[Claims] (1) An upper supporting portion extends over a predetermined angle range,
A tunnel support having a smaller radius of curvature than other support portions including both sides and a lower portion. 2. The method according to claim 1, wherein the upper support portion enters an inner peripheral side of the other support portion, and both ends are respectively connected to both ends of the other support portion via joints. Item 1. Tunnel support according to item 1. 3. Assembling a support in which the upper support portion has a smaller radius of curvature than the other support portions including both sides and the lower portion over a predetermined angle range within the tail hood of the shield body. After the shoring assembly, a tunnel shoring method characterized by installing a sheet pile between an upper shoring portion of the existing shoring and an upper shoring portion of an existing shoring and closing the sheet pile, and then advancing a tail hood. 4. The tunnel support method according to claim 3, wherein said support is made of H-shaped steel, and said sheet piles adjacent to each other in the axial direction of said tunnel are connected on an outer peripheral flange of said support. 5. The strut is made of an H-section steel, and both end portions of the sheet pile are inserted and arranged between the inner and outer peripheral flanges of the strut adjacent to each other in the tunnel axial direction, and between the sheet pile and the inner peripheral flange. The tunnel support method according to claim 3, wherein the sheet pile is fastened to the support by driving a wedge.