JP7543064B2 - How to prevent K-segment from collapsing - Google Patents

Description

The present invention relates to segments assembled circumferentially at the rear of the shield machine after excavation in the shield tunneling method, and in particular to a method for preventing K-segments, which are finally connected circumferentially using a cross-sectional closure method, from falling into the empty space inside the tunnel.

Conventionally, in the shield construction method for urban tunnels, segments with an arc-shaped cross section are assembled in the circumferential direction behind the skin plate of the shield machine while excavating with the shield machine, and the assembled segments are connected in the axial direction of the tunnel to construct a continuous tunnel. In this case, the joints in the circumferential direction of the tunnel are generally called "piece-to-piece joints," and the joints for the assembled segments are generally called "ring-to-ring joints."

Of the multiple segments assembled in the circumferential direction, the last segment to be connected is called the "K segment," and there are two methods for installing this K segment: the cross-sectional closure method and the axial insertion closure method. The former cross-sectional closure method, as shown in Figure 11, is a method in which the K segment 50 is moved radially from the inner space side of the tunnel and connected to adjacent segments 51, 51 on both sides, while the latter axial insertion closure method, as shown in Figure 12, is a method in which the K segment 50 is moved from the tunnel face side in the tunnel axial direction and connected to adjacent segments 51, 51 on both sides.

When the K-segment is closed within the cross section, after closure, tail seal pressure and backfill injection pressure act on the segment when and after the tail seal of the shield machine passes through the segment, and soil pressure, water pressure, etc. act on the part exposed to the outside from the tail seal, causing an axial force to act on the segment. In that case, if the strength of the joints holding the K-segment is insufficient, the K-segment will be displaced toward the tunnel interior, and this displacement will create gaps, which could allow water and soil to flow into the tunnel from the outside.

Possible methods for preventing the K-segment from collapsing include performing secondary lining on the inside of the segment ring at an early stage or arranging reinforcing steel such as H-beams along the inside of the segment ring. Furthermore, the following Patent Document 1 proposes a method for closing a tunnel liner that is formed in a ring shape along the circumferential direction of an excavated tunnel wall and constitutes a tunnel support, in which a number of divided pieces are connected in sequence and finally a key liner is inserted to close the tunnel liner in a ring shape. In this method, a pin or groove is erected on the joint surface of the key liner, and a groove or pin is formed at a position corresponding to the pin or groove on the joint surface of the piece adjacent to the key liner in the circumferential direction, both circumferential side surfaces of the key liner are formed parallel to the radial insertion direction of the key liner, one end of the groove is open in the radial direction of the tunnel liner, the entire groove is hook-shaped, and the shaft of the pin is configured to fit into it. The key liner is inserted from the radial inside into the space between the adjacent pieces, and the pin erected on the joint surface of either the key liner or the adjacent piece is inserted into the groove to position the key liner between the adjacent pieces, thereby closing the tunnel liner in a ring shape.

Japanese Patent Application Publication No. 11-131985

However, methods such as providing a secondary lining on the inside of the segment rings or arranging reinforcing steel materials such as H-beams along the inside of the segment rings require very large-scale construction work and require the temporary removal of piping and equipment arranged on the inside of the segment rings, which poses problems such as a longer construction period and increased construction costs. Also, the method described in Patent Document 1 poses problems such as the need to reconsider the segment joint structure.

The main objective of the present invention is to provide a method for reliably preventing the sagging of K-segments, which are the last of the segments assembled in the circumferential direction and are connected using a cross-sectional closure method, during shield tunneling.

In order to solve the above problems, the present invention relates to a method for preventing the falling of a K-segment that is connected last among a plurality of segments assembled in a circumferential direction in a shield machine after excavation in a shield construction method,
The segments assembled in the circumferential direction are composed of an A segment, which is rectangular in plan view and used as a standard section, two B segments each having an inclined side surface on one side (the K segment side), and a K segment, which is moved radially from the inside of the tunnel between the B segments and connected to the B segment, and the joint positions of each segment assembled in the circumferential direction are arranged so as to be different in the tunnel circumferential direction from the joint positions of the circumferential segments adjacent to the mine portal side, and are further arranged so as to be in the same position in the tunnel circumferential direction as the joint positions of the circumferential segments skipping the segment adjacent to the mine portal side.
Among the multiple segments assembled in the circumferential direction of the tunnel, the last connected K segment is moved radially from the inside of the tunnel and connected to the segments on both sides.
A method for preventing K-segments from falling is provided, which comprises disposing support materials to prevent the K-segments from moving toward the hollow side of the tunnel, and fixing the support materials with post-installed anchors only in the B-segment circumferentially adjacent to the K-segment or the A-segment adjacent to the K-segment in the tunnel axis direction .

In the invention described in claim 1, once the K-segment is installed, a support material is provided to prevent the K-segment from moving toward the hollow side of the tunnel, and the support material is fixed with post-installed anchors only to the B-segment adjacent to the K-segment in the circumferential direction or to the A-segment adjacent to the K-segment in the tunnel axis direction . The support material is not large enough to cover the entire circumference of the tunnel, but is a relatively small device that only holds the K-segment at its periphery so that it does not move toward the hollow side of the tunnel. This means that there is no need to temporarily remove piping and equipment provided inside the segment ring, which does not lengthen the construction period and only increases construction costs by a small amount.

The present invention relates to claim 2 , and provides a method for preventing K -segments from collapsing as described in claim 1, in which a plurality of support materials are arranged on each of both sides of the K-segment in the tunnel circumferential direction, spanning the K-segment and the B- segment adjacent to it in the tunnel circumferential direction, and the support materials are fixed only to the B-segment adjacent to it in the tunnel circumferential direction by post - installed anchors.

The invention described in claim 2 shows a first embodiment of the support material. Specifically, if a plurality of support materials are disposed on both sides of the K segment in the tunnel circumferential direction so as to straddle the K segment and the segment adjacent in the tunnel circumferential direction, these support materials are fixed by post-installed anchors only in the B segment adjacent in the tunnel circumferential direction.

The present invention as claimed in claim 3 provides a method for preventing K-segments from collapsing as described in claim 1, in which a plurality of support members are arranged so as to span across the K -segment and between the B- segments on both sides adjacent to each other in the circumferential direction of the tunnel , and the support members are fixed only to the B-segments on both sides by post-installed anchors.

The invention described in claim 3 shows a second embodiment of the support material. Specifically, if a plurality of support materials are arranged so as to span across the K segment and between the B segments on both sides adjacent in the circumferential direction of the tunnel, these support materials are fixed only on the B segments on both sides by post-installed anchors.

The present invention according to claim 4 provides a method for preventing K-segments from collapsing as described in claim 1, in which support materials are arranged on both sides of the K -segment in the tunnel circumferential direction, spanning the K-segment and the B -segment adjacent thereto in the tunnel circumferential direction, and spanning across the A-segments on both sides adjacent thereto in the tunnel axis direction, and the support materials are fixed by post-installed anchors only in the A- segments on both sides adjacent thereto in the tunnel axis direction.

The invention described in claim 4 shows a third embodiment of the support material. Specifically, if support materials are arranged on both sides of the K segment in the tunnel circumferential direction, straddling the K segment and the adjacent segment in the tunnel circumferential direction and bridging between the adjacent segments on both sides in the tunnel axis direction, these support materials are fixed by post-installed anchors only on the A segments on both sides adjacent in the tunnel axis direction.

As the present invention relates to claim 5 , there is provided a method for preventing K-segments from falling as described in any of claims 1 to 4 , in which the load application point is clarified by interposing small pieces of cushioning material between the support material and each segment.

According to the invention described in claim 5 , small pieces of cushioning material are interposed between the support material and each segment in order to clarify the points of load application.

According to a sixth aspect of the present invention, there is provided a method for preventing a K-segment from falling as described in the fifth aspect, in which a pressure detection means is provided in the cushioning material to control the applied load.

According to the sixth aspect of the present invention, the cushioning material is provided with a pressure detection means for controlling the applied load.

According to a seventh aspect of the present invention, there is provided a method for preventing a K-segment from falling as described in either of the fifth or sixth aspects, in which a strain detection means is provided on the support material to control the stress of the support material.

According to the seventh aspect of the present invention, a strain detection means is provided on the support material, so that the stress of the support material is controlled.

As explained above in detail, the present invention makes it possible to completely prevent the K-segment, which is the last of the segments assembled in the circumferential direction during shield tunneling and is connected using a cross-sectional closure method, from falling.

FIG. 2 is a vertical cross-sectional view of the shield machine 1. FIG. 2 is a development view showing an arrangement pattern of segments. FIG. 11 is an exploded view of a main portion showing a supporting manner of the K segment according to the first embodiment. 4A is a view taken along line IV(A)-IV(A) in FIG. 3, and FIG. 4B is a view taken along line IV(B)-IV(B) in FIG. FIG. 11 is an exploded view of a main portion showing a supporting manner of the K segment in the second embodiment. 6A is a view taken along line VI(A)-VI(A) in FIG. 5, and FIG. 6B is a view taken along line VI(B)-VI(B) in FIG. FIG. 13 is an exploded view of a main portion showing a supporting manner of the K segment in the third embodiment. 7A is a view taken along line VIII(A)-VIII(A) in FIG. 7, and FIG. 7B is a view taken along line VIII(B)-VIII(B) in FIG. FIG. 11 is an explanatory diagram of a dynamic state when a cushioning material 19 is provided in the first embodiment. FIG. 11 is an explanatory diagram of a dynamic state when a cushioning material 19 is provided in the second embodiment. FIG. 13 is an explanatory diagram of the cross-sectional closure method of the K segment. FIG. 13 is an explanatory diagram of the axial insertion closure method of the K segment.

The following describes in detail the embodiments of the present invention with reference to the drawings.

[Shield tunneling method]
The shield machine 1 shown in FIG. 1 is an example of a mud water pressurized type, and a cutter chamber 5 is partitioned between a partition wall 3 and a cutter head 4 provided at the front end of the shield body 2, and a mud feed pipe 6 and a mud discharge pipe 7 are provided with openings facing this cutter chamber 5. Meanwhile, a segment assembly device 10 (erector device) is arranged at the rear side inside the skin plate 8, which is the outer shell of the shield machine 1, and segments 11, 11... consisting of a plurality of pieces are assembled in a ring shape on the inner surface of the skin plate 8 in the circumferential direction as the excavation progresses. A large number of shield jacks 9, 9... are supported by a support frame and arranged at appropriate intervals along the circumferential direction on the periphery of the shield machine 1, and the shield machine 1 advances by extending these shield jacks 9, 9... in a state of abutting against the end face of the assembled segment 11. At the rear of the shield machine 1, backfill material 21 is filled at a predetermined pressure on the back side of the segments 11, starting from the part exposed from the seal tail 20. In this example, a mud pressure type shield machine 1 is shown, but there are various other types, such as a mud pressure type, an earth pressure type, and a muddy earth pressure type.

〔segment〕
Each segment 11, which is arranged circumferentially inside the shield machine 1 and closed into a circle as a whole, is composed of A segments 12, 12... which are rectangular in plan view and used as standard sections, two B segments 13, 13 with only one side (the K segment side) formed to be inclined, and a K segment 14 which is moved radially from the inside of the tunnel between these B segments 13, 13 and connected to the B segments 13, 13, as shown in Figure 2. Each of these segments 12, 13, 14 is connected to each other by inter-piece joints.

The joint positions of each of the segments 11, 11... assembled into a ring are arranged so that they are different in the tunnel circumferential direction from the joint positions of the circumferential segments adjacent to the tunnel entrance, and are further arranged so that they are at the same joint positions in the tunnel circumferential direction as the joint positions of the circumferential segments skipping the segment adjacent to the tunnel entrance. In other words, they are arranged in a so-called staggered manner so that the joint positions are not linearly continuous in the tunnel direction. Segments adjacent in the tunnel axial direction are interconnected by inter-ring joints.

In addition to its own weight, the segment ring 11 is subject to axial force when and after the tail seal 20 of the shield machine 1 passes over the segment 11 due to tail seal pressure, backfill injection pressure, soil pressure acting on the part exposed to the outside from the tail seal 20, water pressure, etc. If the joints of the segment 11 are not strong enough to withstand this axial force, there is a risk of the K segment 14 dropping and moving into the tunnel interior.

In the present invention, in order to prevent the K-segment 14 from falling, a support material is provided to prevent the K-segment 14 from moving toward the hollow side of the tunnel, and the support material is fixed in place by a fixing means.

Below, examples of support forms using the above support materials are explained in order.

<First embodiment>
3 and 4 show a first embodiment of the present invention.

As shown in FIG. 3, the support form of the K segment 14 in the first embodiment is such that a plurality of support materials 15, 15... are arranged on each of both sides of the K segment 14 in the tunnel circumferential direction so as to straddle the K segment 14 and the segment 13 adjacent in the tunnel circumferential direction, and these support materials 15, 15... are fixed to the segment 13 adjacent in the tunnel circumferential direction by a fixing means 16.

Specifically, of the multiple segments assembled in the circumferential direction of the tunnel, the K segment 14, which is the last to be connected, is moved radially from the empty side of the tunnel and connected to the segments (B segments) 13, 13 on both sides and installed. Then, multiple support members 15 of a specified length, about 10 in the illustrated example, are brought in. These support members 15 are preferably made of shaped members with a channel-shaped cross section. In the case of channel-shaped steel, they have a specified level of rigidity and can be brought into close contact with the segments.

Five support members 15 are then arranged along the circumferential direction of the tunnel at the boundary between the K segment 14 and the B segment 13 adjacent in the circumferential direction of the tunnel, straddling the boundary. In this case, it is desirable to arrange them so that the length on the K segment 14 side is short and the length on the adjacent B segment 13 side is long. These support members 15 are then fixed on the B segment 13 side by fixing means 16. Post-installed anchors can be suitably used as the fixing means. The post-installed anchors may be either metal anchors or adhesive anchors. Note that the work can be made more efficient by forming holes for metal anchors or adhesive anchors in advance at the post-installed anchor positions of the B segment 13. An adhesive can also be used to fix the support members 15. In this case, it is preferable to apply adhesive to the entire surface of the segment abutment surface, at least the abutment surface with the adjacent B segment 13.

As shown in Figure 4, the support material 15 is installed only in the required locations, and there is no need to temporarily remove the piping and equipment installed inside the segment ring, making it possible to prevent the K segment 14 from collapsing without lengthening the construction period or increasing construction costs.

<Second embodiment>
Next, a second embodiment of the present invention will be described in detail with reference to FIGS.

As shown in FIG. 5, the support form of the K segment 14 in the second embodiment is such that a number of support members 17, 17... are arranged so as to span across the K segment 14 and between the adjacent segments (B segments) 13, 13 on both sides in the circumferential direction of the tunnel, and these support members 17, 17... are fixed to the B segments 13, 13 on both sides by fixing means 16.

Specifically, the K segment 14, which is to be connected last, is moved radially from the hollow side of the tunnel and connected to the segments (B segments) 13, 13 on both sides, and then multiple support members 17 of a specified length are brought in, about five in the illustrated example. These support members 17 are preferably made of shaped members with a grooved cross section.

Then, the support materials 17 are arranged along the circumferential direction of the tunnel so as to straddle the K segment 14 and span between the B segments 13, 13 on both sides adjacent in the circumferential direction of the tunnel, and then these support materials 17 are fixed to the B segments 13, 13 by fixing means 16. Post-installed anchors can be suitably used as the fixing means. In addition, if adhesive is used to fix the support materials 15, it is preferable to apply the adhesive to the entire surface of the segment abutment surface, at least the abutment surface with the adjacent B segment 13.

As shown in Figure 6, the support material 17 is installed only in the required areas, and there is no need to temporarily remove the piping and equipment installed inside the segment ring, making it possible to prevent the K segment 14 from falling without lengthening the construction period or increasing construction costs.

<Third embodiment>
A third embodiment of the present invention will be described in detail with reference to FIGS.

As shown in FIG. 7, the support form of the K segment 14 in the third embodiment is such that, on each of both sides of the K segment 14 in the tunnel circumferential direction, a support material 18 is arranged so as to straddle the K segment 14 and the adjacent segment (B segment) 13 in the tunnel circumferential direction, and to span between the adjacent segments (A segment) 12, 12 on both sides in the tunnel axial direction, and the support material 18 is fixed to the adjacent segments 12, 12 on both sides in the tunnel axial direction by a fixing means.

Specifically, the K segment 14, which is to be connected last, is moved radially from the hollow side of the tunnel and connected to the segments (B segments) 13, 13 on both sides, and then two support members 18 of a specified length are brought in. These support members 18 basically have a groove-shaped cross section, but because their width is large, they cannot be made from general shaped materials, so they are individually manufactured. A groove-shaped cross section with upright pieces on both sides and in the center is preferably used.

The support material 18 is arranged so as to straddle the K segment 14 and the B segment 13 adjacent in the tunnel circumferential direction, and to span between the A segments 12, 12 on both sides adjacent in the tunnel axial direction. The support material 18 is then fixed in the A segments 12, 12 portion by fixing means 16. Post-installed anchors can be suitably used as the fixing means. If adhesive is used to fix the support material 18, it is preferable to apply the adhesive to the entire surface of the segment abutment surfaces, at least to the abutment surfaces of the adjacent B segment 13 and A segment 12.

<Other form examples>
In the first to third embodiments, small pieces of buffer material 19 are interposed between the supports 15, 17, 18 and the segments 12 to 14, thereby making it possible to clarify the points of load application.

For example, as shown in Fig. 9, in the first embodiment, cushioning material 19 is interposed between the segments 14, 13 and the support material 15. Specifically, cushioning material 19 is interposed between the K segment 14 and the support material 15, cushioning material 19 is interposed between the B segment 13 and the support material 15, and cushioning material 19 is also interposed at the post-installed anchor 16 site between the B segment and the support material 15. When the tensile force of the post-installed anchor is T, the tensile force T is expressed by the following formula (1).
T=P(1+L2/L1)...(1)

It can be seen that the tensile force T is greatly affected by the position of action of P and the reaction force R. For example, if L1 = L2, then T = 2P, and if L1 = 1/2 * L2, then T = 3P. If you want to make T as small as possible, then L2/L1 should be made small. In other words, L1 should be made larger relative to L2. The tensile force of the post-installed anchor can be set using such calculations, but if the positions of action of P and R differ significantly from those assumed, problems may occur. Therefore, in order to reliably clarify the positions of action of P and R, a buffer material 19 is provided between the support material 15 and the segments 13 and 14.

Figure 10 shows an example of the second embodiment. Specifically, a shock absorbing material 19 is interposed between the K segment 14 and the support material 17, and a shock absorbing material 19 is also interposed between the B segment and the support material 17 at the post-installed anchor 16 site.

In cases where the above-mentioned buffer material is used, a pressure detection means may be provided on the buffer material 19 in order to grasp the applied load. Furthermore, a strain detection means may be provided on the support materials 15, 17, etc. in order to manage the stress on the support materials 15, 17, etc.

1...Shield machine, 2...Shield body, 3...Bulkhead, 4...Cutter head, 5...Cutter chamber, 6...Sludge feed pipe, 7...Sludge discharge pipe, 8...Skin plate, 9...Shield jack, 10...Segment assembly device, 11...Segment, 12...A segment, 13...B segment, 14...K segment, 15, 17, 18...Support material, 16...Fixing means (post-installed anchor, etc.), 20...Tail seal, 21...Backfill material

Claims (7)

In a shield construction method, a method for preventing a K segment, which is the last to be connected among a plurality of segments assembled in a circumferential direction in a shield machine after excavation, from falling, comprising:
The segments assembled in the circumferential direction are composed of an A segment, which is rectangular in plan view and used as a standard section, two B segments each having an inclined side surface on one side (the K segment side), and a K segment, which is moved radially from the inside of the tunnel between the B segments and connected to the B segment, and the joint positions of each segment assembled in the circumferential direction are arranged so as to be different in the tunnel circumferential direction from the joint positions of the circumferential segments adjacent to the mine portal side, and are further arranged so as to be in the same position in the tunnel circumferential direction as the joint positions of the circumferential segments skipping the segment adjacent to the mine portal side.
Among the multiple segments assembled in the circumferential direction of the tunnel, the last connected K segment is moved radially from the inside of the tunnel and connected to the segments on both sides.
A method for preventing K-segments from collapsing, characterized in that a support material is arranged to prevent the K-segment from moving toward the hollow side of the tunnel, and the support material is fixed with post-installed anchors only in the B-segment circumferentially adjacent to the K-segment or the A-segment adjacent to the K-segment in the tunnel axis direction . A method for preventing K-segments from collapsing as described in claim 1, wherein a plurality of support members are arranged on each of both sides of the K-segment in the tunnel circumferential direction, so as to span the K-segment and the B -segment adjacent to the K -segment in the tunnel circumferential direction, and the support members are fixed only to the B-segment adjacent to the tunnel circumferential direction by post -installed anchors. A method for preventing K-segments from collapsing as described in claim 1, in which a plurality of support members are arranged so as to span across the K-segment and between the B -segments on both sides adjacent to each other in the circumferential direction of the tunnel, and the support members are fixed only to the B -segments on both sides using post-installed anchors . A method for preventing K-segments from collapsing as described in claim 1, wherein support materials are arranged on both sides of the K-segment in the tunnel circumferential direction, straddling the K-segment and the B- segment adjacent thereto in the tunnel circumferential direction, and horizontally spanning between the A -segments on both sides adjacent thereto in the tunnel axial direction, and the support materials are fixed by post-installed anchors only on the A -segments on both sides adjacent thereto in the tunnel axial direction. A method for preventing a K-segment from falling as described in any one of claims 1 to 4 , wherein the load application point is clarified by interposing small pieces of cushioning material between the support material and each segment. 6. A method for preventing a K-segment from falling as claimed in claim 5 , further comprising the step of providing a pressure detection means for detecting the applied load on said cushioning material. 7. A method for preventing a K-segment from falling as claimed in claim 5 or 6 , further comprising the step of providing a strain detection means on said support material to control the stress of said support material.

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