JPH03110298A - Tunnel - Google Patents

Abstract

PURPOSE:To reduce the amounts of reinforcing bars and concrete as well as reduce the bending moments and shearing force of corners by a method in which arched bent inner and outer corners are formed partly in parts to make up the corners of a tunnel constructed under the ground. CONSTITUTION:Linear segments 2 and B-segments 5 are provided for the bottom face side of a shield tunnel, and corner segments 3 are assembled for both corners. Linear segments 2 to be left-and right-side plates and an upper corner segment 3 are set, linear segment 2 for upside and B-segment 5 are set, and finally a key segment 4 is fitted to form a segment ring A1 closed. Segment rings A2 and A3 are orderly set staggeringly in close contact with the segment ring A1. The adjacent segment rings are connected with bolts, thereby easing stress concentration on the corners.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to tunnels in shield construction methods, propulsion construction methods, mountain tunnels, and the like.

(Prior Art) Various cross-sectional shapes of shield tunnels are used, such as circular, oval, horseshoe, and rectangular shapes.

Traditionally, when constructing subways, etc., double-track sections and underground station sections were constructed using the conventional shield construction method with a circular cross section, but recently, tunnels with irregular cross sections such as rectangular and horseshoe shapes have been constructed with the aim of effectively utilizing underground space. Development is also underway.

FIG. 15 is a sectional view of a conventional rectangular shield tunnel. This rectangular shield tunnel 101 has a corner segment 103 having a right-angled portion at the bottom side, for example, at the left corner, in a horizontal shaft excavated by a shield excavator (not shown).
Next, a rectangular rectangular straight segment 102 is arranged in parallel, and a B segment 105 having an oblique part around 1 is provided at a predetermined position on one side of the segment. Corner segments 103 are provided at the corners, and key segments 104 fitted into the corner segments 103 and the inclined portions of the B segments 105 are inserted to form the bottom side.Hereinafter, the corner segments 103 at the left and right corners will be described. A straight line segment 102 is provided on the top, a corner segment 03 is provided on the upper side, and a straight line segment 102 and a B segment 105 are placed on the ceiling and fixed with a key segment 104 to form one segment ring 101'. As the excavation progressed, this segment 101゛
The next segment ring was arranged on the back side of the segment ring, and these segment rings were fastened to bolts or the like through ring joints 106 provided on the segments.

In such a rectangular shield tunnel 101, the width of the structural axis is 7 m, the height is 5 m, and the cross-sectional thickness of the segment is 0.5 m.
5 m, the moment of inertia of the area is 0.01857 m, and the Young's modulus is 3.6xlO''t/i, and when it is placed in the soil shown in Table 1 above, the pressure shown in FIG. 16 is applied. Under these conditions, when calculating the cross-sectional force using the conventional calculation method based on the "Tunnel Standard Specifications (Shield Edition)", the maximum sectional force at the node number 3'4'' in the figure is
．． A bending moment of 3t-m occurs, and the bending moment between node numbers 3' and 4' reaches a maximum of 27. Ot-m
A positive bending moment will occur. This is illustrated as shown in FIG. 17.

In addition, the shear force diagram is as shown in Fig. 18, with node numbers 3',
A maximum of 33.3 t is generated at the 4° portion, and the axial force diagram is shown in Fig. 19, where a compressive axial force of 33.3 t is generated in the vertical member and 27.3 t in the horizontal member. Compressive axial force of OL is generated.

(Problems to be Solved by the Invention) As mentioned above, in a conventional rectangular shield tunnel, a large bending moment acts on the corners, so haunches 103" shown in FIG. 15 are provided at the corners to increase strength. For example, in order to use a reinforced concrete segment, a large amount of reinforcement was placed in the haunch section to obtain a large amount of strength.For this reason, the amount of reinforcement and concrete also increased, making it uneconomical. Not only that, but there was also the problem of increased dead weight.

The present invention has been made in view of the above circumstances, and its purpose is to reduce the concentrated stress at the corners and to propose an economical tunnel.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a tunnel constructed underground in the shape of a polygon, a horseshoe, etc. with a corner, at least one of the members constituting the corner. This tunnel is characterized by having arc-shaped curved parts formed on both the inside and outside.

(Function) In the present invention, the arc-shaped curved portion provided at a part of the corner makes it possible to disperse the concentrated stress applied to the corner, reducing the bending moment and shearing force at the corner, and reducing the amount of reinforcing steel. and the amount of concrete can be reduced.

(Example 1) Example 1 of the present invention will be described in detail below with reference to FIGS. 1 to 9.

FIG. 1 is a sectional view of the shield tunnel of the present invention, FIG. 2 is a side view of the same, and FIG. 3 is a top view of the same.
, A3 are the eleventh second and third segment rings, respectively. The first segment ring A1 includes a flat straight line segment 2 of equal thickness, and a corner segment 3 consisting of a curved part and a straight part of equal thickness and having the same curvature on the inner and outer diameters at least in part. , and a key segment 4 having a sloped portion on one side when combining the segment rings, and a B segment 5 having a sloped portion to be carved with the key segment 4.

In order to combine this segment ring A1, straight line segments 2 and B segments 5 forming the straight parts on the bottom side are arranged, and corner segments 3 are placed at both corners.
Next, arrange the straight segment 2 that will become the left and right side plates and the upper corner segment 3, respectively, arrange the straight segment 2 and B segment 5 on the top side, and finally maximize the key segment 4 to form a segment ring. Close and form AI.

Next, depending on the state of excavation, as shown in FIGS. 2 and 3, segment rings A2 and A3 are sequentially assembled in close proximity to segment ring A1 and in substantially the same manner.

In this case, it is preferable in terms of strength that the second segment ring A2 is arranged so that the joint positions of the respective segments of the first segment ring AI are shifted. Therefore, the third segment ring A3 is the eleventh segment ring A.
The segments are combined in the same manner as 1, and the joining positions of each segment are arranged in a staggered manner. By arranging them in a staggered manner in the direction of the tunnel, stress can be distributed. Adjustment plates are embedded in the end faces of each of the above-mentioned segments that are abutted adjacent to each other, and in the joint surfaces of the adjacent segment rings. The segments and adjacent segment rings are fastened to each other.

The state will be explained below with reference to FIGS. 4 and 5.

Figure 4 shows straight line segment 2, (a) is a plan view, (b)
is a right side view, and (c) is a top view. In FIG. 4(a), the straight line segment 2, which is made up of a rectangular parallelepiped, has a plurality of reinforcing bars passed through it in the longitudinal direction and the transverse direction, and the periphery of the reinforcing bars is solidified with concrete, etc., and the inner circumferential surface 2a Pocket-shaped box cutouts 6a are provided at predetermined intervals on the upper and lower surfaces 2b in the figure, which are outside the surface, near the ridge line that intersects with the inner circumferential surface 2a. A steel plate 6b is buried in the upper surface 2b side of the box-opening portion 6a, and a bolt hole 6C is provided in the center of the steel plate 6b, and a tunnel direction joint fitting 7 for assembling adjacent segment rings is provided. It is composed. This tunnel direction joint fitting 7 is similarly provided on the back side of FIG. 4(a).

On the longitudinal end surface 2C of this straight segment 2, near the inner circumferential surface 2a, segment joint fittings 8 consisting of a box cutout 6a, a rope plate 6b, and a bolt hole 6C are provided at a plurality of locations, and are butted against the upper surface 2b. The structure is such that it can be fastened to other segments using bolts or the like. Therefore, when the straight line segment 2 is viewed from the inner circumferential surface 2a side, FIG. 4(c)
The shape will be as shown in . That is, tunnel joint fittings 7 are arranged at predetermined intervals on the left and right surfaces in the longitudinal direction of the straight segment 2, and segment coupling fittings 8 are arranged on the lateral surface of the straight segment 2. The number, position, etc. of these tunnel direction joint fittings 7 and segment joint fittings 8 can be increased or decreased as appropriate depending on the size of the tunnel, the ground, etc. Note that the small hole 9 shown in the center of the straight line segment 2 shown in FIG. 4(c) is a hole compatible with backfilling, and can also be used as a hanger during transportation.

FIG. 5 shows corner segment 3, (a) is a plan view, (b)
is a right side view, and (c) is a bottom view. In FIG. 5(a), the corner segment 3 connects the intersection points of two straight line segments perpendicular to each other with a circular arc of a predetermined radius (set according to the size of the tunnel), and forms an arc on at least part of the inner and outer surfaces. It is formed into a single segment having a curved portion in the shape of a shape.

Therefore, the inside and outside of the corner segments are formed by parallel curves, and the widths in plan view are all constant. Several reinforcing bars are pushed through the interior of this corner segment, and the outer periphery of the corner segment is hardened with cement or the like.

The upper surface 3a along the inner circumferential surface of such a corner segment 3
(The same applies to the lower surface), box cutouts 6a similar to those provided in the straight line segment 2 are arranged at predetermined intervals, and a steel plate 6b buried in the upper surface side of the box cutout 6a and a steel plate 6b
A tunnel direction joint fitting 7 is formed by the bolt hole 6c provided in the tunnel direction joint fitting 7. A plurality of segment joint fittings 8 having the same configuration as above are provided on the upper right end surface 3b and the lower end surface 3C of the corner segment 3 (
(See Figures 5(b) and (c)).

In addition, the small hole indicated by 9 in the figure is a backfill compatible hole,
It can also be used as a hanger during transportation.

Hereinafter, although not shown in the drawings, the B segment 5 and the key segment 4 have the same configuration as the straight line segment 2, and the details will be omitted. This B segment 5 and key segment 4
has an inclined part where one end surface overlaps with the other,
When the segmenting A1 is assembled, the key segments 4 are finally fitted and closed.

A straight line segment 2 having the above configuration, a corner segment 3,
Key segment 4 and B segment 5 are combined as follows. A strong steel tube (shield) with an inner diameter slightly larger than the outer diameter of the tunnel is propelled underground, excavation is performed using the face (front end) of the shield, and lining is carried out within the tail at the rear of the shield. During the construction of the lining within this tail, the necessary straight line segments 2 are arranged on the floor surface in a direction perpendicular to the excavation direction of the tunnel. Adjacent portions of each linear segment 2 are fastened to each other via segment joint fittings 8 with bolts or the like. The corner segment 3 is fixed to one end of this tightened straight segment 2, the B segment 5 is attached to the other end, and the key segment 4 is attached by placing the corner segment 3 after a minute. , the corner segment 3 and the B segment 5 are connected and fastened by the key segment 4.

Next, the straight line segments 2 are respectively erected and fastened on the upper end faces of the corner segments 3 at both left and right ends arranged on the floor surface. Corner segments 3 are attached and fastened onto each of the straight line segments 2 erected. Then, attach the straight segment 2 from one side of this corner segment 3,
Thereafter, the first segment ring A1 is assembled using the B segment 5 and the key segment 4 in the same way as the floor work.

When the first segment A1 is assembled in this way,
Assemble the second segment ring A2 to the adjacent part in the tunnel direction. This second segment ring A2 is similar to the first case, but in the second case, each segment is assembled so that the abutting position of each segment is shifted from the abutting position of the first one,
The assembled second segment ring A2 is fastened to the first one via a tunnel direction joint fitting 7 provided on the contact surface.

Next, the third segment ring A3 is assembled in exactly the same manner as in the first case, and the fourth segment ring is assembled in the same manner as the second, so that the joint parts are staggered on the inner and outer peripheral surfaces of the shield tunnel 1. The concentrated stress on each segment ring is dispersed.

The pressure distribution in the shield tunnel 1 assembled in this way is shown in FIG.
"~16" represents the node number of the segment ring.In such a pressure distribution, assuming the same size as the conventional example described above (Ii 7.0 m, height 5.0 m), the installation of this shield tunnel 1 The location was underground as shown in Table 1 above, and the bending moment, shear force, axial force, etc. were calculated using the conventional calculation method based on the "Tunnel Standard Wood Dialect" and were as follows. Furthermore, the cross-sectional dimensions of the segments were the same as those of the conventional example.

(1) For bending moment, node number 3 in the conventional example
A negative bending moment of up to 31.3 t-m at the corners of node numbers 7", 4' and a maximum of 17°9 t-m at the corners of node numbers 7" and 12" in the shielded tunnel of the invention
This resulted in a negative bending moment of approximately 43%. In addition, in the straight part, node numbers 3' to 4 of the conventional example
The maximum is 27. While the positive bending moment of Ot −m was the positive bending moment of the present invention, the
The maximum positive bending moment is 23.4 t-m at the center, which is reduced by about 13%.

This can be represented in a diagram as shown in Fig. 7.

(2) The maximum shearing force was 33.3 t at node numbers 3' and 4' in the conventional example, whereas the shearing force in the present invention is as shown in FIG. , 9
', 10', the maximum shear force is 23.8 t, and the shear force is reduced by about 29%.

(3) Comparing the axial force at the corner, the conventional example had a maximum compressive axial force of 33.3 t in the vertical member, whereas the one of the present invention has a node number of 6″13 as shown in Figure 9. It can be seen that the maximum value is 41.Ot at 0, which is an increase of about 23%.Also, in the straight section, it is 27.Ot at node numbers 3' to 4 degrees, whereas in the present invention, it is 27.Ot at node numbers 9 to 10 degrees. 34.
It was found that the amount increased by approximately 26%.

From the above results, the shield tunnel 1 of the present invention is designed so that the bending moment and shear force at the corners are reduced, and the axial force is increased, compared to the conventional rectangular shield tunnel 101 shown in FIG. The amount of reinforcing bars can be reduced at the top, and the thickness of the segment can also be reduced, resulting in a more economical cross section. Various embodiments of shield tunnels based on the above considerations will be described below.

Example 2 has thinner vertical segments,
Example 3 is a horseshoe-shaped shield tunnel.

(Example 2) Example 2 of the present invention will be described with reference to FIGS. 10 and 11. FIG. 10 shows a segment ring of a variable cross-section shield tunnel, and FIG. 11 shows a corner segment in which (a) is a plan view, (b) is a right side view, and (c) is a bottom view.

Segment ring 1 of this variable cross-section shield tunnel 10
0' means that one end of the corner segment 11 has a modified cross-sectional shape with an intermediate shape. This modified cross-section corner segment 11
As shown in Figure 11, is two orthogonal straight line segments with one side thicker and the other side thinner, with the inner radius and outer radius changed respectively, and the center position eccentrically set. It is curved into an arc shape.

The thick end faces are disposed on the ceiling and floor sides of the shield tunnel, and the vertical straight segments 2 in the vertical direction are formed to be thinner than the straight segments 2 shown in the first embodiment. Therefore, the segment ring 10 shown in FIG.
In ', the ceiling side and the floor side are combined by the straight line segment 2, B segment 5, and key segment 4, and the side parts are connected by the vertical straight segment 12. With this structure, the weight of the shield tunnel can be reduced, and the shield tunnel can be formed with safety from a structural analysis point of view.

In the figure, 7 is the aforementioned tunnel direction joint fitting, 8 is a segment joint fitting, and 9 is a back-fill compatible opening. The assembly of the segment ring lO' of this variable cross-section shield tunnel 10 is substantially the same as in Example I, in which the straight segment 2 and the variable cross-section corner segment 11 are combined and arranged at one corner on the floor side, and B Segment 5 and variable cross-section corner segment 1 are combined and arranged at another corner on the floor side, and this image part is connected with key segment 4 to form the floor side. The segments 12 are assembled by combining various segments on the ceiling side.

A variable cross-section shield tunnel 10 is formed by assembling second, third, etc. segment rings on the tunnel direction side (inner side in the figure) with respect to the assembled first segment ring 10'. , the second segment ring is assembled with the first segment ring 10'' when viewed from the back side of the page, thereby forming the variable cross-section shield tunnel 10.
The outer circumferential surface is formed in a staggered shape, and from a structural analysis perspective, sufficient safety can be expected.

(Embodiment 3) Embodiment 3 of the present invention will be explained with reference to FIGS. 12 to 14. FIG. 12 shows a segment ring of a horseshoe-shaped shield tunnel, and FIG. 13 shows a curved segment, in which (a) is a plan view, (b) is a right side view, and (C) is a bottom view. In addition, Fig. 14 shows segments on a circular arc, (a) is a plan view, (b)
) is a bottom view, and (c) is a side view.

Segment ring 1 of this horseshoe-shaped shield tunnel 13
3゛ is a straight line segment 2, a corner segment 3, a partially curved curved segment 14, an arc-shaped segment 15, an arc-shaped B segment 6, an arc-shaped key segment 1
7.

Among these structural members, the straight line segment 2 and the corner segment 3 are the same as in Example 1, and thereby form the floor side and the side surface, and the curved segment 4, the arcuate segment 15, and the arcuate B segment. H6, arcuate segment 7
etc., it is possible to shield the ceiling side of the horseshoe shape.

As shown in FIG. 13, the curved segment 14 is formed with one end being a straight line, the other end being a curved line equivalent to the inner periphery of the horseshoe shape, and the outer periphery being formed by a line parallel to the inner periphery. It is a constant thing. Tunnel joint fittings 7 are provided at predetermined intervals on the outer end surface near the inner circumferential surface, and segment joint fittings 8 are provided on both end surfaces in the longitudinal direction. Note that 9 in the figure is a backfill compatible hole.

Further, as shown in FIG. 14, the arcuate segment 15 is
The inner circumferential side is formed in accordance with a circular arc to be combined with the horseshoe-shaped ceiling, and the outer circumferential side is also a segment made of a circular arc having a constant thickness. Tunnel joint fittings 7 are provided at predetermined intervals on the end surface near the inner periphery of the arc-shaped segment 15, and segment joint fittings 8 are provided on both end surfaces of the arc shape in the longitudinal direction.

Further, both the arc-shaped B segment 16 and the arc-shaped key segment 17 are formed of circular arcs having the curvature of the arc-shaped segment 15, and one end face is provided with an inclined portion in a different direction, so that the segment ring It is designed to be tightened last during assembly.

Such a horseshoe-shaped segment ring 13'' is assembled from the ceiling floor side and the assembly is completed by tightening the arcuate key segment 17.Then, the second horseshoe-shaped segment ring is assembled by attaching the segment ring of FIG. In addition, in the shield tunnel using horseshoe-shaped segment rings, the linear segments 2
It is also possible to form the (vertical portion) thin. In this case, the corner segment 3 may be changed to a corner segment 11 with a modified cross section.

Although the construction methods of each of the above-mentioned embodiments have been explained mainly using the shield construction method, the tunnel of the present invention can also be applied to the propulsion construction method and mountain tunnels.

(Effects of the Invention) As explained in detail above, the tunnel of the present invention has an arc-shaped curved portion formed on at least a part of the member constituting the corner, both inside and outside. This makes it possible to reduce stress concentration, reduce the amount of reinforcing bars and concrete, and create economical tunnels.

Another advantage is that the optimum tunnel shape can be selected depending on the purpose of use of the tunnel.

[Brief explanation of drawings]

Embodiment 1 of the present invention is shown in FIGS. 1 to 9, in which FIG. 1 is a plan view in the cross-sectional direction of a segment ring of a shield tunnel, FIG. 2 is a side view of the same, FIG. 3 is a top view of the same, and FIG. The figures show the straight line segments that make up the segment ring, (a) is a plan view, (b) is a right side view, (c) is a top view, and Figure 5 is a corner segment, (a) is a plan view, (b) ) is the right side view, (
C) is a bottom view, Figure 6 is a load distribution diagram applied to the segment, Figure 7 is a bending moment diagram of the segment ring, and Figure 8 is a diagram of the bending moment of the segment ring.
The figure is a shear force diagram of the segment ring, and FIG. 9 is an axial force diagram of the segment ring. FIG. 10 and FIG. 11 show Example 2 of the present invention;
The figure is a plan view in the cross-sectional direction of the segment ring of the variable cross-section shield tunnel, and Fig. 11 shows the variable cross-section positive segment.
(a) is a plan view, (b) is a right side view, and (c) is a bottom view. Embodiment 3 of the present invention is shown in FIGS. 12 to 14.
The figure is a plan view in the cross-sectional direction of the segment ring of the horseshoe-shaped shield tunnel, and Figure 13 is a curved segment ring (a
) is a plan view, (b) is a right side view, (c) is a bottom view,
Figure 4 shows arcuate segments, (a) is a plan view, (b) is a bottom view, (c) is a side view, Figures 15 to 19 are conventional examples, and Figure 15 is a segment ring of a rectangular shield tunnel. Fig. 16 is a load distribution diagram on the segment ring, Fig. 17 is a bending moment diagram of the segment ring, Fig. 18 is a shear force diagram of the segment ring, and Fig. 19 is the axis of the segment ring. This is a power diagram. Shield Tunnel 1st Segment Ring Corner Segment Varied Section Corner Segment Arc-shaped Segment Curve Segment OF 15th Ward Figure 19 ρ

Claims (1)

[Scope of Claims] In a tunnel constructed underground and having a polygonal or horseshoe shape with a corner, at least a part of the member constituting the corner has an arc-shaped curved part on both the inside and outside. A tunnel characterized by the formation of