JP2018100582A - Widening structure for tunnel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a widening structure for a tunnel capable of inhibiting excessive flexure moment and deformation even with a flat structure widened in a cross direction.SOLUTION: There is provided a widening structure for a tunnel in which upper parts of two cylindrical tunnels (1,2) disposed at an interval are covered by an arch-shaped upper widening part 3. The widening structure comprise: reinforcement beams 51,52 which are respectively disposed between the opposite ends 31,31 of the upper widening part and inner surfaces 111,211 of a lining part 11,21 of a first tunnel 1 and a second tunnel 2; and a lower chord member 7 which connects between the lower ends 511,521 of the reinforcement beams arranged at opposite sides.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a widening structure of a tunnel in which an upper portion of two cylindrical tunnels arranged at intervals is covered by an arch-shaped widening portion.

  In recent years, the scale of underground structures such as roads, subway lines, and station buildings constructed in the basement has been increasing, and such underground structures have been constructed at a large depth. With so-called deep underground usage, which was enacted in 2001, infrastructure facilities that can be constructed at depths of 40 meters or deeper are clearly defined, especially in urban areas such as the Tokyo metropolitan area, and the demand for construction has increased. The current situation is. Furthermore, with the spread of shield construction technology, the extension of the underground passage has become longer, and there are cases in which large-section tunnels are formed in some sections of the underground passage by post-construction of branch junctions along the way. It is done.

  As a widening structure of a tunnel constructed by expanding and expanding a lining portion of a plurality of tunnels in such a branching junction or the like, for example, the widening structure of a shield tunnel and a construction method of Patent Document 1 are known.

  In the construction method disclosed in Patent Document 1, a part of a plurality of parallel tunnels is removed and widened, and a wide lining body is formed between each tunnel to be joined to the respective tunnel lining body. To widen. Further, a reinforcing beam for supporting the joint portion is installed in the vicinity of the joint portion between the tunnel lining body and the widening lining body of each tunnel. By installing this reinforcing beam, stress concentration at the joint can be relaxed.

  Patent Document 2 discloses a tunnel merging structure in which a connecting portion with an upper beam having an arch shape whose roof has a smaller arch shape is provided between the main line shield and the lamp shield. It is disclosed. In this structure, the main line shield and the lamp shield are joined by joining both ends of the arch-shaped upper beam with a tensile member. That is, the tension member opposes the force to expand the space between the leg portions of the arch by a load applied to the arch-shaped upper beam from above.

JP 2011-241637 A JP 2009-62682 A

  However, the tension member disclosed in Patent Document 2 can reduce the axial force transmitted from the arch-shaped upper beam to the reinforcing beam, but acts on the main line shield on which the reinforcing beam is installed and the lamp shield itself. Since the axial force generated in the reinforcing beam due to the load cannot be reduced, a large negative bending occurs in the lining portion near the lower end of the reinforcing beam. For this reason, a highly rigid segment is used for the lining part of the main line shield and the lamp shield.

  Accordingly, an object of the present invention is to provide a tunnel widening structure that can suppress the occurrence of an excessive bending moment and deformation even in a wide and flat structure that is widened.

  In order to achieve the above object, the widening structure of a tunnel according to the present invention is a widening structure of a tunnel in which an upper portion of two cylindrical tunnels arranged at intervals is covered with an arch-shaped widening portion. The reinforcing beams interposed between the end portions on both sides of the widened portion and the inner side surface of the lining portion of the tunnel adjacent thereto are connected to the lower ends of the reinforcing beams disposed on both sides. And a lower chord material.

  Here, the reinforcing beam may be configured to be extended in accordance with the extending direction of the end portion of the widened portion. The reinforcing beam may be joined to the lining portion via a receiving member, and an end portion of the lower chord material may be connected to the receiving member. Further, the lower chord material may be formed of flat steel and arranged such that the thickness direction is the tunnel axis direction.

  In the tunnel widening structure of the present invention configured as described above, between the end portions on both sides of the arch-shaped widened portion covering the upper portion of the two tunnels and the inner side surface of the lining portion of the two tunnels. Reinforcing beams are interposed, and the lower ends of the reinforcing beams are connected by a lower chord material.

  Thus, by connecting the lower ends of the reinforcing beams with the lower chord material, the horizontal component of the axial force generated in the reinforcing beams can be borne by the tensile force of the lower chord material. For this reason, it is possible to suppress the occurrence of an excessive bending moment in the lining portion even in a wide structure that is wide and wide. In addition, it is possible to suppress the occurrence of a large deformation that causes the widened structure to collapse laterally.

  Furthermore, by extending the reinforcing beam in accordance with the extending direction of the end of the widened portion, the axial force generated in the widened portion can be reliably transmitted to the reinforcing beam, and excessive stress can be prevented from occurring in the lining portion. it can.

  Also, if the end of the lower chord material is connected to the receiving member with respect to the reinforcing beam to be joined to the lining portion via the receiving member, the reinforcing beam and the lower chord material can be easily integrated. .

  Such a lower chord material can be provided in a space-saving manner by flat steel. Furthermore, by arranging the flat steel so that the thickness direction is in the tunnel axis direction, the rigidity against vertical deflection can be increased, and a fireproof plate or the like serving as a ceiling surface can be attached.

It is explanatory drawing which showed the structure of the widening structure of the tunnel of this Embodiment. It is a perspective view for demonstrating the structure of the widening structure of the tunnel of this Embodiment. It is sectional drawing explaining the structure of an enlarged cross-section part. It is a perspective view for demonstrating the connection state of a reinforcement beam and a lower chord material. It is explanatory drawing which showed typically the load which acts on a widened cross-section part, and the force which generate | occur | produces. It is the analysis result figure which showed the bending moment distribution which generate | occur | produces in the widening cross-section part of this Embodiment. It is the analysis result figure which showed the bending moment distribution which generate | occur | produces in the widening cross-sectional part in which the lower chord material is not arrange | positioned as a comparative example. It is an analysis result figure which showed the deformation | transformation which generate | occur | produces in the wide cross-section part of this Embodiment. It is an analysis result figure which showed the deformation | transformation which generate | occur | produces in the wide cross-sectional part in which the lower chord material is not arrange | positioned as a comparative example. It is the analysis result figure which showed the bending moment distribution which generate | occur | produces in the widening cross-section part of this Embodiment performed by changing analysis conditions. It is the analysis result figure which showed the bending moment distribution which generate | occur | produces in the widened cross-section part which connected between the upper ends of the reinforcement beam with the lower chord material as a comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a configuration of a tunnel widening structure according to the present embodiment. The widened cross-sectional portion 10 provided with the widened structure of the tunnel is formed in a flat structure that is wide and laterally connecting two tunnels (1, 2) arranged at intervals.

  The two tunnels (1, 2) are, for example, a first tunnel 1 that is a main tunnel and a second tunnel 2 that is a ramp tunnel. The first tunnel 1 and the second tunnel 2 respectively constructed in a cylindrical shape by a shield method or the like are widened cross-sectional portions 10 that are cut out and communicated with each other at a branch / merging portion.

  In short, the widened cross-sectional portion 10 includes the first tunnel 1 and the second tunnel 2 arranged on both sides in the width direction, the upper widened portion 3 as an arch-shaped widened portion covering the upper portion of the tunnel, and the lower portion of the tunnel. It is mainly comprised by the lower wide part 3A which connects between.

  The first tunnel 1 and the second tunnel 2 have outer shells formed by lining portions 11 and 21 for protecting the tunnel interior. As shown in FIG. 2, the lining portions 11 and 21 are formed in a cylindrical shape by combining arc plate-like segments.

  The segments constituting the lining portions 11 and 21 include a steel segment, a reinforced concrete segment, a composite segment using both steel and concrete, a ductile segment, and the like.

  A state in which circular plate-like segments are connected in the circumferential direction and formed in an annular shape is referred to as one ring, and the covering parts 11 and 21 are formed in a cylindrical shape by continuously connecting a plurality of rings in the tunnel axis direction.

  And in the widened cross-sectional part 10, the segment of the removal parts 12 and 22 shown by the dashed-two dotted line in FIG. 1 is removed. That is, the first tunnel 1 and the second tunnel 2 are in a state in which the side of the center side of the widened cross-sectional portion 10 is opened.

  The upper widened portion 3 is bridged in an arch shape between the upper edge of the opening of the first tunnel 1 and the upper edge of the opening of the second tunnel 2. Here, a portion where the end portion 31 of the upper widened portion 3 and the lining portions 11 and 21 are integrated is referred to as a joint portion 4. On the other hand, a portion where the lower widened portion 3A and the lining portions 11 and 21 are integrated is referred to as a joint portion 4A.

  As shown in FIG. 2, the upper widened portion 3 and the lower widened portion 3A are also formed by arc plate-like segments. The main girder portion 32 of the upper widened portion 3 has an arch shape, and the leg portions on both sides are supported by the first tunnel 1 and the second tunnel 2.

  The reinforcing beam 51 is disposed so as to be continuous with one end portion 31 of the upper widened portion 3. Specifically, as shown in FIG. 1, the end portion 31 of the upper widened portion 3 and the lining portion 11 of the first tunnel 1 are continuous at the joint portion 4, and a reinforcing beam is formed on the joint end surface 41 of the joint portion 4. An upper end 512 of 51 is attached.

  The reinforcing beam 51 serving as an axial force member is extended in accordance with the extending direction of the end portion 31 of the upper widened portion 3, and the lower end 511 intersecting the cylindrical cover portion 11 is covered with the receiving member 6. The inner surface 111 of the part 11 is fixed.

  On the other hand, the reinforcing beam 52 is disposed so as to be continuous with the other end 31 of the upper widened portion 3. Specifically, the end 31 of the upper widened portion 3 and the lining portion 21 of the second tunnel 2 are continuous at the joint 4, and the upper end 522 of the reinforcing beam 52 is attached to the joint end surface 41 of the joint 4. It is done.

  The reinforcing beam 52 serving as the axial force member is also extended in accordance with the extending direction of the end portion 31 of the upper widened portion 3, and the lower end 521 intersecting the cylindrical cover portion 21 is connected to the cover portion via the receiving member 6. 21 is fixed to the inner surface 211 of the member 21.

  As shown in FIG. 4, the reinforcing beam 51 is formed of, for example, an H-shaped steel material. Then, the lower end 511 of the reinforcing beam 51 is attached to the pedestal surface 61 of the receiving member 6. The receiving member 6 is a triangular prism-shaped member whose back surface 63 is formed in accordance with the shape of the inner surface 111 (211) of the lining portion 11 (or the lining portion 21).

  The receiving member 6 is manufactured by combining steel materials, and the lower end 511 of the reinforcing beam 51 is joined to the pedestal surface 61 of the receiving member 6 by bolting or welding via an end plate. The receiving member 6 on the first tunnel 1 side and the receiving member 6 on the second tunnel side of the widened cross-sectional portion 10 are connected by the lower chord material 7.

  FIG. 4 is an enlarged perspective view showing a connection state between the reinforcing beam 51 and the lower chord member 7. A trapezoidal plate-like lower chord bonding material 71 for attaching the lower chord material 7 is attached to the inclined lower surface 62 of the receiving member 6 by welding or the like.

  The end portion 7 a of the lower chord material 7 is attached to the lower chord bonding material 71. For example, the end portion 7a of the lower chord member 7 formed into a plate shape with flat steel or the like is butted against the side end face of the lower chord bonding member 71, and the bonding plate 73 is bridged and joined with bolts 72,. Can do. The end 7a of the lower chord material 7 and the lower chord bonding material 71 can be joined by welding.

  Since the lower chord member 7 functions as a tensile member, a tensile force acts on the joint portion between the end portion 7 a and the lower chord joint member 71. On the other hand, if it is the method of spanning the joining plate 73 formed with a steel plate etc. and joining with the volt | bolts 72 and ... and a nut, it can construct easily and can demonstrate a tensile strength reliably. it can.

  FIG. 2 shows a structure in which the lower ends 511 and 521 of the reinforcing beams 51 and 52 are connected to each other by the lower chord members 7 through the receiving members 6 and 6 from the inside of the widened cross-sectional portion 10. It shows the state of looking up. That is, a plurality of lower chord members 7,... Are arranged at intervals in the axial direction of the tunnel.

  A fireproof plate 8 can be attached to the lower surface of the lower chord members 7,... Arranged like joists as shown in FIG. If the fireproof plate 8 is arranged in a ceiling or floor shape, the workability is excellent, and a fireproof section can be easily provided.

  The upper ceiling space partitioned by the fireproof plate 8 includes a passage space 81 for an administrator and an operator to pass during maintenance inspection, an equipment space 82 for installing facilities necessary for ventilation, lighting, and the like. Can be used.

  Next, the operation of the tunnel widening structure of the present embodiment will be described.

  A load (Q1, Q2, Q3) as shown in FIG. 5 acts on the widened cross-sectional portion 10 having a wide, flat structure that has been widened. The vertical load Q <b> 1 acts as a distributed load on the upper surface of the lining portion 11, the upper widening portion 3, and the lining portion 21 according to the depth in the ground where the widened cross-sectional portion 10 is constructed. On the other hand, a horizontal load Q2 acts on the side of the first tunnel 1 as a side pressure, and a horizontal load Q3 acts on the side of the second tunnel 2 as a side pressure.

  When the vertical load Q1 is applied to the widened cross-sectional portion 10, the axial force is transmitted from the end portions 31 and 31 of the upper widened portion 3 to the reinforcing beams 51 and 52 and is transmitted to the reinforcing beams 51 and 52 as indicated by arrows. Part of the axial force is transmitted to the lining parts 11 and 21, and the horizontal component is transmitted to the lower chord member 7 serving as a tensile member and is borne.

  FIG. 6A shows an analysis result when a load (Q1, Q2, Q3) is applied to the widened section 10 of the present embodiment, and a bending moment as shown in the figure is generated in the outer shell. Here, the bending moment illustrated on the inner side of the widened cross-sectional portion 10 is defined as a positive bending moment, and the bending moment illustrated on the ground side is defined as a negative bending moment.

  On the other hand, FIG. 7A is an analysis result diagram showing the deformation that occurs in the widened cross-sectional portion 10 of the present embodiment. As shown in this figure, the widened cross-sectional portion 10 is deformed so as to spread laterally (illustrated by a two-dot chain line), and it can be seen that the lower chord material 7 functions as a tensile material.

  Here, in order to confirm the performance of the widened section 10 of the present embodiment, the comparative example in which the lower chord member 7 is not disposed is also analyzed, and the bending moment distribution diagram is shown in FIG. 6B and the deformation diagram is shown in FIG. 7B. Indicated.

  In the structure of the widened cross section a10 as a comparative example, the upper part of two cylindrical tunnels (a1, a2) is covered with an arch-shaped wide part a3. Reinforcing beams a51 and a52 are connected to the leg portions on both sides of the widened portion a3, respectively. And the structure equivalent to the lower chord material 7 of this Embodiment does not exist.

  In such a widened cross section a10 of the comparative example, a large negative bending moment (negative bending) is generated in the lining portion near the lower ends of the reinforcing beams a51 and a52. Specifically, a large negative bending moment of m1 = −5700 kNm / R is generated near the lower end of the reinforcing beam a51 and m2 = −5400 kNm / R is generated near the lower end of the reinforcing beam a52.

  On the other hand, in the widened section 10 of the present embodiment shown in FIG. 6A, the vicinity of the lower end of the reinforcing beam 51 is M1 = -1400 kNm / R, and the vicinity of the lower end of the reinforcing beam 52 is M2 = -1400 kNm / R and m1, Only a small bending moment occurred compared to m2.

  The largest negative bending moment generated in the widened section 10 is M3 = -4500 kNm / R at the lower part of the widened section 10 on the first tunnel 1 side, and M4 = at the lower part of the widened section 10 on the second tunnel 2 side. -3700 kNm / R, which is about 30% to 40% smaller than m1 and m2 generated in the widened cross section a10 of the comparative example.

  On the other hand, regarding the deformation, as shown in FIG. 7A, the maximum displacement of the widened cross-sectional portion 10 of the present embodiment was 140 mm as a displacement D1 near the center of the upper widened portion 3. On the other hand, in the widened cross section a10 of the comparative example, as shown in FIG. 7B, the displacement d1 at the same position was 170 mm. From these results, it can be said that the widened cross-sectional portion 10 of the present embodiment has a maximum displacement of about 20% smaller than that of the comparative example, and can suppress the occurrence of large deformation.

  Furthermore, the comparison with another comparative example was performed by changing the analysis conditions. FIG. 8A is a bending moment diagram showing an analysis result in the widened section 10 of the present embodiment, and FIG. 8B is a bending moment diagram showing an analysis result according to another comparative example.

  In the structure of the widened cross section b10 as a comparative example shown in FIG. 8B, the upper part of two cylindrical tunnels (b1, b2) is covered with an arch-shaped widened part b3. Reinforcing beams b51 and b52 are connected to the leg portions on both sides of the widened portion b3, respectively. The leg portions of the widened portion b3 are connected by the lower chord material b7.

  Even in the widened cross-section b10 in which the lower chord material b7 is arranged, a large negative bending moment (negative bending) is generated in the lining portion near the lower ends of the reinforcing beams b51 and b52. Specifically, a large negative bending moment of m11 = −6600 kNm / R was generated near the lower end of the reinforcing beam b51.

  On the other hand, in the widened cross-sectional portion 10 of the present embodiment shown in FIG. 8A, only a very small bending moment was generated near the lower end of the reinforcing beam 51 as compared with M11 = −800 kNm / R and m11.

  Thus, even if compared with the widened cross-sectional part b10 where the position where the lower chord material b7 is arranged is different, the widened cross-sectional part 10 of the present embodiment suppresses occurrence of an excessive bending moment in the lining parts 11 and 21. I can say that.

  In the widened cross-sectional portion 10 provided with the tunnel widening structure of the present embodiment thus configured, the end portions on both sides of the arch-shaped upper widened portion 3 that covers the upper portion of the two tunnels (1, 2). Reinforcing beams 51 and 52 are respectively interposed between the inner surfaces 111 and 211 of the lining portions 11 and 21 of the two tunnels 31 and 31, and the lower chord material between the lower ends 511 and 521 of the reinforcing beams 51 and 52. 7 to connect.

  By connecting the lower ends 511 and 521 of the reinforcing beams 51 and 52 with the lower chord material 7 in this way, the horizontal component of the axial force generated in the reinforcing beams 51 and 52 disposed obliquely is borne by the tensile force of the lower chord material 7. Can be made.

  For this reason, it is possible to suppress the occurrence of an excessive bending moment in the lining portions 11 and 21 even in the widened flattened widened cross-sectional portion 10 that is widened. If negative bending generated in the lining portions 11 and 21 can be reduced, the specifications of the segments constituting the lining portions 11 and 21 can be rationally simplified to reduce material costs and weight. .

  Moreover, generation | occurrence | production of the big deformation | transformation in which the widened cross-sectional part 10 is laterally crushed can also be suppressed. If the deformation of the widened cross-sectional portion 10 is suppressed, the influence on the surrounding ground and the ground surface can be minimized.

  Further, by extending the reinforcing beams 51 and 52 in accordance with the extending direction of the end portions 31 and 31 of the upper widened portion 3, the axial force generated in the upper widened portion 3 is reliably transmitted to the reinforcing beams 51 and 52 and covered. It can suppress that an excessive stress arises in the construction parts 11 and 21.

  Further, if the reinforcing beams 51 and 52 to be joined to the lining portions 11 and 21 through the receiving members 6 and 6 are connected to the receiving members 6 and 6, the ends 7 a and 7 a of the lower chord material 7 are also connected. The reinforcing beams 51 and 52 and the lower chord material 7 can be easily integrated.

  Such a lower chord material 7 can be provided in a space-saving manner by flat steel. In addition, by arranging the flat steel so that the thickness direction is the tunnel axis direction, it is possible to increase the rigidity against vertical deflection, and it is possible to attach the fireproof plate 8 or the like serving as the ceiling surface.

  Here, if the refractory plate is directly attached along the inner surface of the deformed cross section that gradually changes in the tunnel axis direction, it is expected that the number of used sheets will increase in addition to the time and effort required for construction. On the other hand, if the lower chord members 7,... Arranged at intervals in the tunnel axis direction are attached to, for example, the lower surface side, the workability is excellent, and a fireproof compartment can be formed with a small number of sheets. It becomes possible.

  The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes that do not depart from the gist of the present invention are not limited to this embodiment. Included in the invention.

  For example, in the above-described embodiment, the lower chord material 7 formed of flat steel has been described as an example. However, the present invention is not limited to this, and is not limited to this, such as H-shaped steel, groove-shaped steel, PC steel rod, PC Any member that can bear a tensile force, such as a steel strand, can be used for the lower chord material.

10 Widened section 1 First tunnel (tunnel)
11 Inner side 111 Inner side 2 Second tunnel (tunnel)
21 lining part 211 inner side surface 3 upper widened part (widened part)
31 Ends 51 and 52 Reinforcement beams 511 and 521 Lower end 6 Receiving member 7 Lower chord material 7a End

Claims (4)

A widening structure of a tunnel in which a space between upper portions of two cylindrical tunnels arranged at intervals is covered with an arch-shaped widening portion,
Reinforcing beams respectively interposed between the end portions on both sides of the widened portion and the inner side surface of the lining portion of the tunnel adjacent to the widened portion;
A tunnel widening structure, comprising: a lower chord member connected between lower ends of the reinforcing beams disposed on both sides.   The tunnel widening structure according to claim 1, wherein the reinforcing beam is extended in accordance with an extending direction of an end of the widened portion.   3. The tunnel according to claim 1, wherein the reinforcing beam is joined to the lining portion via a receiving member, and an end portion of the lower chord material is also connected to the receiving member. Widening structure.   4. The tunnel widening structure according to claim 1, wherein the lower chord material is formed of flat steel and is disposed so that a thickness direction thereof is a tunnel axis direction. 5.