JP5935756B2 - Seismic reinforcement structure for joints of submerged tunnels. - Google Patents

Description

  The present invention relates to a seismic reinforcement structure for a joint portion of a submerged tunnel (a submarine tunnel by a submerged box), and particularly relates to a seismic reinforcement structure for improving the water stop performance of the joint portion.

  FIG. 1 is an example of the structure in the longitudinal direction (tunnel axis direction) of a submarine tunnel (submerged tunnel) 10 by a submerged box 11. A plurality of submerged boxes 11 (here, No. 1 to No. 6 boxes) are installed between the shafts 12, and each box has a length of about 110 m.

  FIG. 2 shows an example of the structure in the transverse direction (the direction perpendicular to the tunnel axis) of the submarine tunnel (submerged tunnel) 10 by the submerged box 11. In FIG. 2, 13 is reinforced concrete, and 16 is a steel plate for water stoppage.

  FIG. 3 is a structural example of a joint portion (submerged box joint portion) 21 between the submerged boxes 11. FIG. 3 shows a joint portion between the ceiling side portions of the submerged box 11. A rubber gasket 23 is arranged in a compressed state on the end face (contact frame) 22, and a reinforcing bar 15 protruding from the sinking box 11 is connected by a grip joint (grip joint) 24. After the sinking boxes 11 are connected to each other by the reinforcing bars 15, post-cast concrete 25 is placed in the recessed portions. In some cases, the rubber gasket 23 is a primary waterproof rubber, and a secondary waterproof rubber (not shown) is disposed inside the rubber gasket 23.

  In such a submarine tunnel 10 using the submerged box 11, when the seismic motion to be subjected to the seismic design is larger than that at the time of construction, the joint portion 21 between the submerged boxes 11 becomes insufficient in strength, and the joint between the submerged boxes 11 opens. It may become large and water stoppage may not be secured sufficiently.

  Therefore, in the Sakishima tunnel of Osaka Port, measures against the joint opening were connected by reinforcing steel plates at the joint part of the submergence box in order to prevent joint opening in response to insufficient strength of the joint part due to the review of earthquake motion. (See Non-Patent Document 1).

  That is, FIG. 4 shows the seismic reinforcement structure using the above-described reinforcing steel plate. In the submerged box joint portion 21 shown in FIG. 3, the reinforcing steel plate 31 is provided inside the tunnel of the joint portion 21 as the seismic reinforcement structure. It is attached with anchor bolts 33.

Seismic reinforcement of the connecting part of the sinking box, Nikkei Construction, Nikkei BP, March 27, 2009, P.I. 26-31

  However, when using a seismic reinforcement structure that connects the submerged boxes with reinforcing steel plates as described in Non-Patent Document 1 above, the load acting on the fixing portion of the reinforcing steel plate to the submerged box is large, It is necessary to lengthen the fixing portion and fix it with a large number of anchor bolts. As a result, the reinforcing steel plate itself becomes heavier and the workability deteriorates.

  In addition, the reinforcing steel sheet has a larger cross-sectional area than existing anchored reinforcing bars, etc., and when deformed in the direction in which the sinking boxes are separated from each other during an earthquake more than expected, the load acting on the fixing part of the reinforcing steel sheet is large. Therefore, the fixing unit itself may be damaged. For this reason, it is impossible to deny the possibility that the water-stopping property is not secured and the buried tunnel is flooded.

  On the other hand, rubber anti-seismic joint repair joints have been put to practical use as an anti-seismic measure for the existing structure of concrete culverts used in sewers and joint grooves.

  Since this seismic joint repair joint is made of rubber, even if joint joint opening occurs, the force acting on the anchor of the anchoring portion is small, so that it can be anchored with a small amount of anchor. For example, the anchor fixing interval is 330 mm, and the water pressure resistance when submerged from the outside of the culvert is 0.1 MPa or less (water pressure of a depth of about 10 m).

  However, the joint part of the submerged box is often located at a depth suitable for anchor anchoring (1 m or more) and at a water depth of 10 m or more. It is impossible to apply seismic joints.

  The present invention has been made in view of the circumstances as described above, and can secure water stoppage of a submerged tunnel joint part (submerged box joint part) even during an earthquake more than expected, and can be easily attached. It is an object of the present invention to provide a seismic reinforcement structure for a joint part of a submerged tunnel.

  In order to solve the above problems, the present invention has the following features.

  [1] A seismic reinforcement structure for a joint part of a submerged tunnel, wherein a corrugated steel sheet for reinforcement is attached to the entire inner periphery of the tunnel of the joint part.

  [2] The seismic reinforcement structure for a joint part of a submerged tunnel according to [1], wherein a waterproof resin excellent in tensile strength is applied between the joint part and the corrugated steel sheet for reinforcement.

  [3] The reinforcing corrugated steel sheet has a corrugated portion for absorbing joint openings of the joint portion, and has straight portions for fixing the joint portion on both sides of the corrugated portion. The seismic reinforcement structure for a joint part of a submerged tunnel according to [1] or [2] above.

  The seismic strengthening structure of the joint part of the submerged tunnel according to the present invention can secure water stoppage of the joint part (submerged box joint part) of the submerged tunnel and can be easily attached even during an earthquake more than expected.

  That is, in this invention, the water stop performance of the joint part (submerged box joint part) of a submerged tunnel can be improved efficiently.

It is an example of the structure in the longitudinal direction (tunnel axis direction) of the submarine tunnel by submerged box. This is an example of the structure in the transverse direction of the submarine tunnel (in the direction perpendicular to the tunnel axis) by submerged box. It is a structural example of the joint part (submerged box joint part) of a submarine tunnel. It is the figure which showed typically the earthquake-proof reinforcement structure of the nonpatent literature 1. It is a figure which shows the earthquake-proof reinforcement structure in Embodiment 1 of this invention. It is a cross-sectional shape of the corrugated steel sheet for reinforcement in Embodiment 1 of the present invention. It is a load-displacement relationship when the both ends of the corrugated steel sheet for reinforcement in Embodiment 1 of this invention are loaded in a horizontal direction. It is another example of a shape of a corrugated part of corrugated steel sheet for reinforcement in Embodiment 1 of the present invention (there is a straight section). In Embodiment 1 of this invention, it is explanatory drawing of the corrugated steel plate cover for reinforcement required for a road surface part. It is a figure which shows the earthquake-proof reinforcement structure in Embodiment 2 of this invention. In the Example of this invention, it is the figure which compared the relationship of the load of a tension | pulling direction, and a displacement about the reinforcing steel plate of a comparative example, and the corrugated steel plate for reinforcing of this invention example. In the Example of this invention, it is a figure which shows the displacement state of the horizontal direction in the ground part corresponded to a submerged box part. It is a figure which shows the joint opening amount of the submerged box joint part in a prior art example. It is a figure which shows the joint opening amount of the submerged box joint part in a comparative example. It is a figure which shows the joint opening amount of the submerged box joint part in the example 1 of this invention. It is a figure which shows the joint opening amount of the submerged box joint part in the example 2 of this invention.

  Embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1]
FIG. 5 is a diagram showing a submerged box joint portion according to Embodiment 1 of the present invention.

  As shown in FIG. 5, in the first embodiment, in the submerged box joint portion 21 shown in FIG. 3, as a seismic reinforcement structure, a waveform is formed in the tunnel axis direction over the entire inner periphery of the tunnel of the submerged box joint portion 21. The reinforcing corrugated steel plate 32 is attached with anchor bolts 33.

  That is, the corrugated steel plate 32 for reinforcement has a corrugated portion 32a for absorbing the joint opening of the submerged box joint portion 21, and is fixed to the submerged box joint portion 21 by the anchor bolts 33 on both sides of the corrugated portion 32a. It has a straight part 32b for the purpose.

  Thereby, in this Embodiment 1, the load of the fixing | fixed part to the submerged box 11 does not become excessive, and the water-stopping inside the submarine tunnel 10 (submerged box 11) can be ensured efficiently.

  That is, since the corrugated steel plate 32 for reinforcement is attached to the entire inner periphery of the tunnel of the submerged box joint portion 21, the corrugated steel plate 32 for reinforcement deforms even if a displacement that causes joint opening occurs in the submerged box joint portion 21. However, the water-stopping property is ensured.

  Further, since the corrugated steel sheet for reinforcement 32 is easily deformed in the tunnel axis direction, it has a characteristic that a large load is not transmitted to the fixing portion to the submerged box 11 even when deformed. Therefore, the reinforcing corrugated steel plate 32 can be easily fixed to the sinking box 11.

  In addition, the corrugated steel plate 32 for reinforcement gives the margin of the length of the target joint opening amount which ensures water stop between the fixing points by the anchor bolts 33 (section contacting the post-cast concrete 25) in the submerged box. What is necessary is just to form a waveform so that it may become length. A shape that requires a large amount of joint opening and that does not obstruct the space inside the tunnel inevitably requires a plurality of waveforms.

  Below, the result of having examined numerically about the concrete shape and performance of a corrugated steel sheet for reinforcement is shown.

  First, cross-sectional shapes (folded shapes) to be examined are shown in FIGS. 6 (a) and 6 (b). 6A is a model in which the horizontal length of the corrugated portion is 60 cm (waveform portion 60 cm model), and FIG. 6B is a model in which the horizontal length of the corrugated portion is 40 cm (waveform portion 40 cm model). is there. 6A and 6B, points a and b indicate both ends of the straight line portion (that is, both ends of the corrugated steel sheet for reinforcement).

  The following four cases (Case 1 to Case 4) combining the above-mentioned cross-sectional shapes with material properties were subjected to three-dimensional FEM analysis in which the steel plate part was modeled as a shell element and the contact part with the submerged box joint part was modeled as a solid element. .

(Case 1) Corrugated part 60cm model, plate thickness 15mm, all materials are SS400 (rolled steel for general structure)
(Case 2) Corrugated part 60 cm model, plate thickness 15 mm, straight part material SS400 (rolled steel for general structure), corrugated part material LY100 (low yield point steel for building structure)
(Case 3) Corrugated part 40cm model, plate thickness 15mm, all materials are SS400 (rolled steel for general structure)
(Case4) Corrugated part 40cm model, plate thickness 15mm, straight part material SS400 (rolled steel for general structure), corrugated part material LY100 (low yield point steel for building structure)

  The corrugated portion is processed to have an arc shape with a radius of 5 cm. In the corrugated portion 60 cm model, the length of the corrugated portion along the corrugated portion is 94.2 cm, which is 34.cm longer than the horizontal length of 60 cm. It is 2cm long. In the corrugated portion 40 cm model, the length along the corrugated portion is 62.8 cm, which is 22.8 cm longer than the horizontal length of 40 cm. (Hereafter, the amount that is longer is referred to as a margin).

  On the other hand, the material properties are as follows.

SS400 is rolled steel for general structure, the Young's modulus (primary ^{slope) 2.0 × 10 5 N / mm} 2, although yield strength 282N / mm ² (yield point used in the design is often a 235N / mm ² As the yield point is larger, the force acting on the fixing portion becomes larger. Here, in order to obtain an average yield point, 235 N / mm ² is multiplied by 1.2), and the secondary gradient after yield is 1 It was set to 1/1000 of the next gradient (2.0 × 10 ⁵ N / mm ² ). The elongation of a steel plate with a plate thickness of 15 mm is guaranteed to be 17% or more.

LY100 is an extremely low yield point steel, Young's modulus is 5.0 × 10 ⁴ N / mm ² , yield strength is 100 N / mm ² , and the secondary gradient after yield is 1.33 × 10 ³ N until the strain is 0.1. / Mm ² , and the cubic gradient thereafter was 1.00 × 10 ² N / mm ² . The elongation of the steel sheet is guaranteed to be 50% or more.

  7A and 7B show the relationship between the load and the displacement obtained by loading the points a and b horizontally. FIG. 7A shows Case 1 and Case 2, and FIG. 7B shows Case 3 and Case 4. Here, the calculation is performed using a model in which the depth direction is 10 cm.

  As shown in FIG. 7 (a), in Cases 1 and 2, the load increases from around the margin of 34.2 cm due to bending into a waveform. Similarly, as shown in FIG. 7B, in Cases 3 and 4, the load increases from around the margin of 22.8 cm resulting from bending into a waveform.

  Regarding the difference in material, the load can be suppressed to about 40% to 70% by using LY100 for the bent portion (corrugated portion) in the stationary section below the margin.

  Further, in Case 1 in FIG. 7A and Case 3 in FIG. 7B, a mark marked on the load-displacement relationship is a point corresponding to the lower limit of 17% of the elongation of the steel sheet. If the limit value of elongation is exceeded, there is a possibility of breakage, so it is necessary to assume use within the limit. Regarding Case2 and Case4, the lower limit value of elongation is 50%, and therefore, the elongation limit is not reached within the illustrated range.

  From the above results, the limit of correspondence for joint opening in each case is as follows.

Case 1: 14cm (about 40% of the margin 34.2cm)
Case 2: Up to 50 cm or more is possible (however, mounting up to about 30 cm is easier because the force acting on the fixing part is smaller)
Case3: 9.2cm (about 40% of the margin 22.8cm)
Case 4: Up to 40 cm or more is possible (however, mounting up to 30 cm is easier because the force acting on the fixing part is smaller)

  Therefore, when using a general structural rolled steel (SS400), a margin of 2.5 times or more (a reciprocal of 40%) of the joint opening total amount is provided with a corrugated shape, and a low yield point steel for a building structure (LY100). In the case of (), the margin allowance more than 1 times the total amount of joint opening may be given by the waveform shape.

  6 (a) and 6 (b), the cross-sectional shape (bent shape) is a shape in which an arc having a radius of 5 cm is combined. However, as shown in FIG. 8, a straight section is provided in the middle of the arc-shaped portion. By adding, you can earn a margin. In this case, however, the amount protruding from the inner wall of the tunnel increases.

  In addition, the margin can be easily increased by increasing the number of bendings. However, for example, on the road surface portion (the bottom side of the sinking box 11), as shown in FIG. 9, a cover (reinforcing corrugated steel plate cover 35) that can handle the load of the passing vehicle is attached so as to cover the corrugated portion 32a. It is normal. In such a case, the number of bendings may be adjusted in accordance with the material of the corrugated steel sheet for reinforcement and the size of the cover. In addition, 36 in FIG. 9 is a pavement part.

[Embodiment 2]
FIG. 10 is a view showing a submerged box joint part in Embodiment 2 of the present invention.

  As shown in FIG. 10, in this second embodiment, in the seismic reinforcement structure of the first embodiment of the present invention shown in FIG. 5, the tensile strength is further increased between the submerged box joint portion 21 and the corrugated steel sheet 32 for reinforcement. An excellent waterproof resin 34 is applied.

  When an earthquake more than expected is applied, the post-cast concrete 25 may crack when it moves in the direction in which the submerged boxes 11 are separated from each other, and may collapse when it moves to the compression side. For this reason, when the rubber gasket 23 stops functioning, there is a concern that a large water pressure is applied to the corrugated steel sheet 32 for reinforcement and water leakage gradually occurs from the gaps of the anchor bolts 33 and the like.

  In contrast, in the second embodiment, as described above, the waterproof resin 34 having excellent tensile strength is interposed between the submerged box joint portion 21 (post-cast concrete 25) and the corrugated steel plate 32 for reinforcement. The occurrence of water leakage as described above can be avoided.

  As the waterproof resin 34 having excellent tensile strength, a polyurethane resin, a polyware resin, or the like can be considered.

  As an example of the present invention, the submerged box joint portion 21 was evaluated for the conventional example, the comparative example, the present invention example 1 and the present invention example 2 for the submarine tunnel 10 shown in FIG.

  Incidentally, the conventional example is a submerged box joint portion without reinforcement shown in FIG. 3, the comparative example is a submerged box joint portion to which the reinforcing steel plate 31 shown in FIG. 4 is attached, and Examples 1 and 2 of the present invention are shown in FIG. It is a submerged box joint with a corrugated steel plate 32 for reinforcement attached.

The reinforcing steel plate 31 in the comparative example is a steel plate having a tensile strength of 400 N / mm ² and a thickness of 15 mm. The material characteristics were the same as SS400 of Case1. Further, the corrugated steel sheet 32 for reinforcement in Invention Examples 1 and 2 is a corrugated steel sheet obtained by processing the reinforcing steel sheet 31 in the above comparative example into a corrugated shape. In Invention Example 2, Case 2 was applied.

  First, FIG. 11 shows the relation between the stress and strain in the tensile direction (per 0.1 m in the direction perpendicular to the tunnel axis) of the reinforcing steel sheet of the comparative example and the corrugated steel sheets of the first and second invention examples. The corrugated steel sheet for reinforcement was converted from the load-displacement relationship of FIG.

  As shown in FIG. 11, the tensile rigidity of the corrugated steel sheet for reinforcement of Example 1 of the present invention is about ¼ of the reinforcing steel sheet of the comparative example, and the tensile rigidity of the corrugated steel sheet for reinforcing of Example 2 of the present invention is the reinforcement of the comparative example. It is about 1/167 of the steel plate, and it can be seen that it has a characteristic of being greatly deformed with a small load.

  Next, the axial behavior of the submarine tunnel 10 when a certain earthquake motion acts on the ground portion corresponding to the submerged box 11 portion with a horizontal displacement difference is examined.

  FIG. 12 shows a horizontal displacement state in the ground portion corresponding to the submerged box 11 portion. This displacement is applied as a forced displacement to the analysis model. In the analysis model, the materials constituting the submerged box 11, the submerged box joint portion 21, and the shaft 12 for analyzing the axial behavior of the submarine tunnel 10 are modeled by fiber elements. A ground spring is disposed in the submerged box 11 and the vertical shaft 12, and a forced displacement is input to the ground side of the ground spring.

  FIG. 13 shows the joint opening amount of the submerged box joint portion in the conventional example obtained by the above method. A joint opening of No. 1 box and No. 2 box has a joint opening of 30 mm, and the reinforcing bars connecting the sinking boxes yield. A joint opening of No. 2 box and No. 3 box has a joint opening of 22.2 mm, and the reinforcing bars connecting the sinking boxes yield. A joint opening of No. 3 box and No. 4 box has a joint opening of 14.2 mm, and the reinforcing bars connecting the sinking boxes yield. A joint opening of No. 4 box and No. 5 box has a joint opening of 14.3 mm, and the reinforcing bars connecting the sinking boxes yield.

  If the reinforcing bar of the joint part yields, the joint opening will easily proceed, so it is difficult to ensure water-stopping with only the rubber gasket, and it is necessary to perform seismic reinforcement.

  Next, FIG. 14 shows the joint opening amount of the submerged box joint part in the comparative example, FIG. 15 shows the joint opening amount of the submerged box joint part in Example 1 of the present invention, and FIG. Indicates the amount of joint opening.

Table 1 shows the result of comparing the tensile force acting on the reinforcing steel material in the comparative example and the tensile force acting on the corrugated steel sheet for reinforcing in the inventive examples 1 and 2. Table 2 shows that each of the comparative example and the example of the present invention has a diameter of 1 mm per 1 m width (anchor bolt shown in FIG. 4) required for fixing using an anchor bolt having a diameter of 16 mm and an allowable shear stress of 80 N / mm ² . 33 indicates the number of anchor bolts per 1 m in the depth direction of the paper on one side of the fixing unit.

As shown in FIG. 14, in the comparative example, the maximum joint opening amount of the submerged box joint portion is reduced to 0.6 mm, and the effect of seismic reinforcement is very remarkable. However, as shown in Table 1, in the comparative example, the tensile force acting on the reinforcing steel material is 9.52 × 10 ^{4 to} 1.21 × 10 ⁵ kN, and as shown in Table 2, in the comparative example, The anchor bolts necessary for fixing the reinforcing steel plate in the sinking box are required to be 86 to 110 per 1 m width on one side.

On the other hand, as shown in FIG. 15, in Example 1 of the present invention, the maximum joint opening amount of the submerged box joint portion is reduced to 16.3 mm, and the effect of seismic reinforcement is remarkable. Moreover, as shown in Table 1, in Invention Example 1, the tensile force acting on the corrugated steel material for reinforcement is 1.71 × 10 ^{4 to} 2.72 × 10 ⁴ kN, which is smaller than that of the comparative example. As shown in FIG. 2, the anchor bolts required for fixing the corrugated steel sheet for reinforcement in the submerged box are 16 to 25 per 1 m width on one side.

Furthermore, as shown in FIG. 16, in Example 2 of this invention, the maximum joint opening amount of a submerged box joint part is reduced to 23.7 mm. Moreover, as shown in Table 1, in the present invention example 2, the tensile force acting on the corrugated steel material for reinforcement is 9.39 × 10 ^{3 to} 1.14 × 10 ⁴ kN, which is smaller than that of the comparative example. As shown in Fig. 2, only 9 to 10 anchor bolts are required per 1 m width on one side to fix the corrugated steel sheet for reinforcement in the sinking box.

  Thus, in Examples 1 and 2 of the present invention, the effect of suppressing the joint opening amount is not as great as that of the comparative example, but the number of anchor bolts necessary for fixing is suppressed to about 10 to 20% of the comparative example. Can do.

  Therefore, in the present invention examples 1 and 2, even if the seismic motion more than expected acts and the joint opening amount of the joint portion occurs, it can be followed with a margin, even if the rubber gasket or the secondary waterproof rubber breaks. , Can ensure water-stopping.

  The shape of the corrugated portion of the corrugated steel sheet for reinforcement, the number of corrugations, and the material of the steel material may be designed with respect to the amount of joint opening that can cope with an unexpected earthquake.

10 Submarine tunnel (submerged tunnel)
DESCRIPTION OF SYMBOLS 11 Submerged box 12 Standing pile 13 Reinforced concrete 14 Concrete 15 Reinforcement 16 Steel plate for water stop 21 Submerged box joint part 22 Contact frame 23 Rubber gasket 24 Grip joint (grip joint)
25 Post-cast concrete 31 Reinforcing steel plate 32 Reinforced corrugated steel plate 33a Corrugated portion 33b Straight line portion 33 Anchor bolt 34 Waterproof resin 35 Reinforced corrugated steel plate cover 36 Pavement portion

Claims (2)

It is a seismic reinforcement structure for a joint part of a submerged tunnel, and has a corrugated steel sheet for reinforcement over the entire tunnel inner periphery of the joint part ,
A seismic reinforcement structure for a joint portion of a submerged tunnel, wherein a waterproof resin excellent in tensile strength is interposed between the joint portion and the corrugated steel sheet for reinforcement. The reinforcing corrugated steel sheet has a corrugated portion for absorbing joint openings of the joint portion, and has straight portions for fixing the joint portion on both sides of the corrugated portion. The seismic reinforcement structure of the joint part of a submerged tunnel according to claim 1 .