JPS6187099A - Construction method of flat tunnel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Use The present invention relates to a method for constructing flat tunnels such as undersea tunnels by the segment lining method.

<fl>Prior Art Conventionally, when constructing underwater tunnels under ports and rivers, a shield construction method using a shield with a circular cross section has been used.

Generally, the cross section of a tunnel is circular in shape to withstand the large earth pressure from the top, bottom, left and right of the excavated ground.

Particularly in cases such as those located under the seabed, the cross section is usually circular in order to sufficiently withstand the earth pressure from the surrounding area.

In recent years, automobile tunnels have been desired to have wide lanes, and the current situation is that their circular cross-sections have become extremely large in accordance with the width of the lanes.

<l[[>Problems to be Solved by the Invention The following problems exist in tunnels using conventional large-section circular shields as described above.

(a) Circular tunnels with large cross-section shields create extra space at the top, which increases buoyancy in shallow areas, so the cart must be made larger.

(b) As shown in Fig. 10, when the road vertical alignment a is shallow, the distance mt of the road surface is short when installing other than the part below the water surface.
The tunnel extension d is also shortened, whereas in the case of a l-channel using a circular shield with a large cross section, the lengthwise line j and the longitudinal line A become deep.

Therefore, if the installation is done in a part other than the water surface part, the distance of the passage B part will be longer and the tunnel will be longer. (Fig. 9) The present invention was developed to solve the above-mentioned problems, and by constructing a tunnel that has a flat cross section and can withstand earth pressure, it gives buoyancy to the tunnel. We provide a construction method for flat undersea tunnels, etc., which can reduce excess space, keep the tunnel load low, and further reduce the length of the tunnel to λ0 by making the road longitudinal alignment shallower. The purpose is to

<iv>Means for solving the problems In the present invention,
The fifth segment in the lining method
In order to construct a flat tunnel that has a flat cross section and can withstand large earth pressure, we adopted a method of introducing prestress in the circumferential direction of segments 1 to 1.

That is, a circumferential groove into which a PC cable can be fitted is provided at each connecting portion in the circumferential direction of each segment or in the circumferential direction at the center portion of each segment.

Then, the PC cable is passed through a sheath made of a flexible material, and is fitted into the circumferential groove.

After assembling the segments, the proximal end of each PC cable was fixed to a part of the segment, the free end was exposed inside the segment, prestress was introduced in the axial direction, and then the cable was exposed to the inner wall of a part of the segment. Prestress is applied in the circumferential direction by the PC cable.

<V> Effect As described above, a glass material through which a PC cable is passed is installed in the circumferential groove provided in the circumferential direction of each segment 1~, and this PC
Introducing prestress into the cable strengthens the circumferential bond of each segment.

In addition, 1 DC in the circumferential groove provided in the circumferential connection part.
When the cable is fitted, it is compressed into the flexible sheath (inner product) direction groove and closes the boundary line between each segment, thereby increasing the water-tightness of the boundary line portion aligned in the axial direction.

<Vl> Example Next, the construction method of the flat tunnel of this Komei will be explained based on the drawings.

This embodiment is the third segment lining method in the well-known shield construction method, in which two types of PC cables 1.2 are covered with flexible sheaths (the third is wrapped around the circumference of the segments assembled flat). To apply prestress in the direction (fourth formation).

(a) In this embodiment, the PC cable has both ends at a tensioned end 11 and a fixed end 12 at
47. ; two PC cables 1 with tensioned ends 21 at both ends, and one PC cable 2 with tensioned ends 21 at both ends.

7I Nawara (Multiple pieces assembled in a flat manner 1~
Connect the adjacent parts with two PC cables 1, such as tension end 11 and fixing end 12, and connect the remaining part,
Both ends are connected to the tensile end portion 21 with one piece of PC cable 2 covering the other end.

Each PC cable 1.2 is then placed in a crosswise manner so that adjacent segments of each section are closely tied together.

(b) Sheath material (FIGS. 4 to 7) The sheath material 3 is a plurality of rod-shaped members that fit into circumferential holes (i4), which will be described later, formed at the boundaries of each segment by axially connecting the segments.

The sheath material 3 has flexibility, and each segment has the same curvature as the PC cable 1 in the longitudinal direction.
A PC cable hole 31 into which two cables 2 can be inserted is opened. (
(Fig. 4) However, in order to cross each PC cable 1.2 so that the adjacent covering segments of each part are tightly connected, a sheath material 3 is attached to the part where each PC cable 1.2 is placed twice. The split sheath material 32 is divided into two in the longitudinal direction, and the PC cable hole 31 is inserted into each half (Fig. 5).The ratio of division is as shown in Fig. Rather than being divided, the dividing line is configured to be displaced from the center.In other words, the divided sheath material 32 is configured such that the dividing line is displaced from the center.
The half described later? &41 is configured so that when it is fitted into the circumferential groove 4 formed by connecting the two segments, the dividing line of the split sheath material 32 is not small on the boundary line between both segments.

In addition, 3 minutes of sheath material! , 11t! It is also conceivable that the I-) C cable hole 31 be opened in a way so that two PC cables can be inserted therein (14).

Further, as will be described later, the sheath material that fits into the circumferential groove 4 portion formed by the connection of the two fastening portion segments 6 is the sixth
-Construct into the shape shown in Figure 7.

That is, a pull-in part 33 for pulling the PC cable into the segment is provided protrudingly at the lower part of the split sheath material 32.
A continuous hole is formed in the C cable hole 31 so that the strained end 11.21 of each PC cable is exposed to the outside.

(c) Segments (Figure 2.3.8) In this example, a plurality of segments are combined to form a segment ring with a flat cross section, so the overall shape of each segment and its curvature are as shown in Figure 1. etc. use two types of segments, each of which is different or has a different function and will be explained below.

Incidentally, the respective segments are connected by means of axial and circumferential clearances q+jpol 1- as before. Also, it is the same as before that the axial direction: DC cable hole J is opened for applying prestress in the axial direction.

[General segments] (Fig. 2) Some segments 5 are formed by connecting the conventional legmen 1 in the axial direction of the tunnel, with a circumferential groove 4, such as a U-shape, formed at the boundary line. It is.

That is, the half-groove 41 is formed by cutting out the long side 52 on the outer peripheral side of a conventional segment which is given a certain curvature in the direction of the long sword of a long plate surrounded by short sides 51 and long sides 52, etc.

Further, a part of the general segment 5 is provided with a fixing portion 53 for fixing the fixing end 12 of the PC cable 1 to the segment.

[Fastening part segment 1 (Fig. 3.8) The fastening part log mentro is a retracting part of the split sheath material 32 from the half groove 41 toward the back side of the segment in order to expose the PC cable 1.2 to the back side of the segment. This is a member that has a window 61 into which the holder 33 is inserted.

A fastening notch 62 for fastening the PC cable is formed on the back side of the fixture, and the window 61 and the fastening notch 62
are connected through a through hole 63 through which the PC cable is passed.

The window portion 61 and the fastening notch 62 may be inserted into only one half groove 41 of the segment or both half grooves 41.

J3, as mentioned above, it is also conceivable that the circumferential grooves 4 carved in each segment 1 to 1 are carved in the central portions of the segments.

Next, a method of constructing a flat tunnel using each of the above-mentioned members will be explained.

(B) Excavation In this example, is the tunnel excavation knee itself a segment lining made using the conventional shield method? Go (Koyoru)

(b) Wrapping the sheath material to the PC cable Wrap the FA 'N' 3 around each of the PC cables 1 and 2.

That is, either one of the split sheath members 32 that serve as the lead-in portion 33 is encased around the tensioned end portion 11 of each PC cable 1 .

Further, one of the split sheath members 32 that does not have the retracting portion 33 is wrapped around the fixing end portion 12 portion.

Furthermore, since the portion adjacent to the fixing end 12 portion is a portion that overlaps with the PC cable 2, one of the divided sheaths 1 and 32 -h is encased.

The other part of the PC cable is wrapped in an undivided sheath (13).

On the other hand, the PC cable 2, which has tensioned ends 21 at both ends, is encased with either one of the split sheaths 32 with a pull-in part 33 on the tension end 21 side, and a pull-in part 33 in the adjacent part. Either one of the split sheath members 32 that is not in use is encased.

The currently used split sheath material 32 is one that forms the shape of the undivided sheath material 3 with the split sheath material 32 of the PC cable 1 described above.

As described above, three PC cables having each sheath material encased are constructed.

At this time, each sheath material is configured to curve in the same direction so that each sheath material group forms an arc.

(c) Assembling each segment (Fig. 1) Connect each segment in the space within the tail of the shield machine and assemble it into a flat segment ring.

That is, after connecting the plurality of general segments 5, the general segments 5 each having the fixing portion 53 are connected to both ends thereof.

Then, the window portion 61 sides of the two fastening portion segments 6 are roughly connected to both ends thereof.

Next, the fastening notches 6 of the above two fastening portion segments 6
Connecting a plurality of general segments 5 in succession from the 2 side,
A fastening portion segment 6 is arranged in the segment of the part where the annular ironwork is closed, and the window portion 61 side thereof is connected.

The lining constructed as described above is located with its cross section cut out.

That is, each segment assembled flat has a half groove 41 located on its outer circumferential portion, and a window portion 61 is carved obliquely toward the inner circumferential side in the fastening portion segment 6 portion.

(d) Mounting of PC cables Each PC cable 1.2 wrapped with sheath material 3 corresponding to each part is positioned in the exposed half-groove 41.

That is, the fixing ends 12 of the two PC cables 1 are fixed to the fixing part 53 of the general segment 5, and each tensioned end part 11 is crossed with each other so that the retracting part 33 of the split sheath material 32 is connected to each window of the fastening part segment 6. 61.

On the other hand, the lead-in portion 33 of the split sheath material 32 encased by the PC cable 2 having tensioned ends 21 at both ends is inserted into the window portion 61 of the fastening portion segment 6 adjacent to the general segment 5 having the fixing portion 53 .

Each tensioning end 11.21 is then positioned within the fastening cutout 62.

(e) Introduction of pre-stressing PC cables 1.2 should be attached to the designated locations of each segment. After that, connect new segments corresponding to each PC cable in the axial direction as shown in Figure 8. do.

After completing the connection of the axial segments, 1DC in the axial direction
A prestress is introduced in the axial direction by the axial PC cable J1 in the cable hole J.

Thereafter, tension is applied to the bowed long ends 11.21 of each PC cable 1.2 to introduce prestress in the circumferential direction of the segment.

In the above embodiment, three PC cables were used to introduce prestress, but it goes without saying that the number of cables and the method of distributing the cables are not limited to those in this embodiment.

The point is that it is sufficient to introduce prestress from the inside of the segments to tighten all the segments in the circumferential direction.

Drawing of Nn bottom tunnel By repeating the process of applying prestress in the circumferential direction of the segments as described above to construct the tunnel, a tunnel with a flat cross section is constructed (14).

<, VU> Effects of the Invention Since the present invention has been described above, the following effects can be expected.

(b) By introducing prestress in the circumferential direction to the lining,
Even if the cross section is not circular but flat, it can sufficiently withstand earth pressure, and a tunnel with high toughness and layer resistance can be constructed.

(b) As a result of being able to construct a tunnel with a flat cross section, the extra space that gives buoyancy to the tunnel can be reduced, and as a result, the load on the tunnel can be kept low.

(c) Since the height of the tunnel cross section can be kept low, the road vertical alignment of the entire tunnel can be made shallow.

Therefore, installation outside of the water surface allows the road portion to be shortened and the overall tunnel length to be shortened.

(d) By introducing prestress in the circumferential direction of ffiI, the water-stopping properties of the tunnel can be improved.

In particular, when a circumferential groove is provided at the boundary line where each segment connects in the axial direction, and when prestress is introduced via a PC cable with an iJ flexible sheath wrapped around it, the sheath material is inserted into the groove. Since it is in close contact with the segment, water-stopping properties can be greatly improved at the axial connection portion of the segments.

[Brief explanation of drawings]

Fig. 1.2 An explanatory diagram of a segment ring assembled with a flat cross section according to the present invention. Fig. 2: An explanatory diagram of a general segment used in the present invention. Fig. 3.2 An explanatory diagram of a fastening segment used in the present invention. Figures 4 to 7: An explanatory diagram of the sheath material used in the present invention. Figure 8: An explanatory diagram of the portion where the fastening segments are adjacent. 10th = An explanatory diagram of an undersea tunnel when the road longitudinal alignment is deep. 10th = Road Explanatory diagram of a submarine tunnel when the longitudinal alignment is shallow 1.2: PC cable 3: Sheath material 42 Circumferential groove 5
:, General segment 6: Fastening segment A: Road vertical alignment B: Installation is road R2 tunnel extension applicant Taisei Corporation Figure 2

Claims (1)

[Claims] In the shield construction method, segments are assembled into a flat cross section, a PC cable is fitted into a groove cut in the circumferential direction of the segment, and prestress is introduced from the inside of the segment. Features: Construction method for flat tunnels.