JP2020007793A - Tsunami barrier - Google Patents

Abstract

To provide a tsunami barrier in which displacement of a wire rope is suppressed, which avoids a collision of the wire rope with a protection object in capturing a drift even when installed in a place close to the protection object, and which is excellent in workability.SOLUTION: A tsunami barrier 1 of this invention comprises: a plurality of posts 2 erected on a foundation with a predetermined interval; and a screen 3 bridged between the plurality of posts 2 and capturing an object that is made to flow toward a protection object by a wave force. The screen 3 includes a pretension processed wire rope 31.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tsunami barrier that captures drifting objects and the like when a tsunami or storm surge occurs.

2. Description of the Related Art A drifting substance catching fence (tsunami barrier) is known that captures drifting substances such as driftwood and debris flowing out due to a tsunami or a flood, thereby protecting a protection target such as a power transmission tower from invading drifting substances. The tsunami barrier is, for example, an end support installed at four corners of the tsunami barrier, an intermediate support installed between the end support, and a PC erected over the support in multiple steps. And a wire rope formed of a steel stranded wire (for example, see Patent Document 1).
The end struts and the intermediate struts absorb the impact energy of drifting objects due to tsunamis, storm surges, and the like due to deformation and the like, and the wire ropes absorb the impact energy by extending. The installation position of the tsunami barrier is determined in consideration of the distance between the protection target and the support and the wire rope, the deformation of the support, and the elongation of the wire rope.

JP-A-2006-125211

By the way, the tsunami barrier may be installed in a place where it is difficult to secure a sufficient space between the tsunami barrier and a protection target depending on the conditions of the installation place. If the tsunami barrier and the object to be protected are close to each other, the wire rope that has captured the drifting object extends toward the object to be protected, and the drifting object remains on the wire rope even though the wire rope has captured the drifting object. There is a possibility that the wire rope may collide with the protection target, and there is a demand to reduce the amount of extension (displacement) of the wire rope.
For example, in order to reduce the amount of displacement of the wire rope, it is conceivable to increase the number of intermediate supports to reduce the distance between the supports or increase the diameter of the wire rope. However, when the number of intermediate supports is increased, the workability of the tsunami barrier is reduced, the construction period is extended, and the cost is increased. In addition, when the diameter of the wire rope is increased, the workability decreases with an increase in weight, and the cost increases.

  On the other hand, for example, as shown in Patent Literature 1, it is known to use a PC steel stranded wire having a large elastic modulus and a high yield stress as a material of a wire rope installed between columns. However, if the elastic modulus and the yield stress increase, it is necessary to increase the strength of the end strut on which the PC stranded wire is laid so that the end strut does not deform or collapse before the PC stranded wire yields. . As a result, the diameter of the pillar increases, and the cost of the tsunami barrier increases.

  In view of the above, the present invention has been made in view of the above problems, and the displacement of the wire rope is suppressed. An object of the present invention is to provide a tsunami barrier with excellent workability that avoids collision with a target.

  In order to solve the above-mentioned problem, the present invention provides a plurality of pillars which are erected at a predetermined interval on a foundation, and which is bridged between the plurality of pillars and flows to a protection target by the force of waves. And a screen for capturing an object that has been removed, said screen having a pretensioned wire rope.

  Further, the wire rope absorbs the absorbed energy of the object by deforming, and the wire rope bridged between the columns has a displacement amount based on a predetermined absorbed energy, and the wire rope and the protection target are displaced. Is preferably smaller than the interval of

  Further, it is preferable that the yield stress of the wire rope is smaller than the yield stress of the column.

  In addition, it is preferable that an interval between the protection target and the wire rope is close to each other.

  In the tsunami barrier according to the present invention, the displacement of the wire rope is suppressed, and even when installed in a place close to the protection target, it is possible to avoid collision between the wire rope and the protection target when catching a drifting object. It has excellent workability.

FIG. 1 is a perspective view of a tsunami barrier surrounding a protection target. FIG. 2 is a plan view schematically showing the configuration of the tsunami barrier. It is a graph which shows the displacement control effect of a φ10 wire rope. It is a graph which shows the displacement control effect of a φ16 wire rope. It is a graph which shows the displacement control effect of a φ20 wire rope. It is a graph which shows the displacement control effect of a φ25 wire rope.

  A preferred embodiment of the present invention will be described with reference to the drawings. The embodiment described below is one example, and various forms can be taken within the scope of the present invention.

<Structure of tsunami barrier>
FIG. 1 is a perspective view of a tsunami barrier surrounding a protection target. FIG. 2 is a plan view schematically showing the configuration of the tsunami barrier.
The tsunami barrier 1 shown in FIG. 1 surrounds a protection target T such as a power transmission tower, which is constructed in a coastal area or an area near the seaside. For example, the protection target T may need to be constructed on a site surrounded by roads, fields, rivers, third-party lands other than the owner of the protection target T, and the like. Therefore, the tsunami barrier 1 needs to be installed close to the protection target T.

  The tsunami barrier 1 is a fence structure for catching drifting substances that are washed away with the tsunami and approaching the protection target T, and for preventing damage or collapse of the protection target T due to collision of the drifting substances. The tsunami barrier 1 includes a plurality of columns 2 and a screen 3 spanned between the columns 2.

(Post)
Each pillar 2 is erected on a foundation buried in the ground. As shown in FIG. 2, the columns 2 are erected on the ground so as to be aligned on a straight line, and the direction of the columns 2 is changed along the way. That is, the location where the arrangement direction changes is the corner portion C of the tsunami barrier 1. Since the tsunami barrier 1 is formed in a rectangular shape in a plan view, the arrangement direction of the columns 2 is changed at four places so as to have four corners C.
The plurality of columns 2 include a locking column 21 for locking the end of the screen 3 and a supporting column 22 for supporting the screen 3, each of which is formed of a steel pipe.
Locking struts 21 are provided at each corner C of the tsunami barrier 1, and supporting struts 22 are provided at predetermined intervals between the locking struts 21.

The locking column 21 is stronger than the supporting column 22 that supports the middle of the screen 3, and more specifically, has a diameter larger than that of the supporting column 22 so as to withstand the tension acting on each screen 3, the load at the time of yielding, and the like. It is configured to be large. The locking strut 21 is larger in diameter and thickness than the support strut 22, and is connected to the upper end of a pile buried deep in the ground.
The locking strut 21 is designed to absorb the collision energy of a drifting object or the like colliding with the locking strut 21 by locally deforming (recessing) the strut. In other words, the locking strut 21 captures the drifting material that has been washed away by the tsunami or storm surge without being destroyed while being locally deformed even if it hits the locking strut 21.

  The support columns 22 are provided by a predetermined number between the pair of locking columns 21 and support the screen 3. The number of the support columns 22 to be installed may be appropriately selected according to the interval between the locking columns 21 installed at the corners C. The support column 22 is designed to absorb the collision energy of a drifting object or the like that has collided with the support column 22 by deforming the beam (beam deformation).

(screen)
For example, when a tsunami or a storm surge occurs, the screen 3 catches the drifting object due to a drifting wave rushing from the sea to the land to prevent the protection target T from being damaged or collapsed by the collision with the protection target T. It becomes a capturing body.
The screen 3 has, for example, a plurality of screen materials that are passed through the arranged columns 21 and 22 at a plurality of locations in the height direction. The screen material is a wire rope 31 and is inserted through each of the columns 21 and 22 along a horizontal direction orthogonal to the axial direction of each of the columns 21 and 22. Each wire rope 31 is erected so that its extending direction is parallel to each other, and is laid between the locking struts 21 installed at the corner C of the tsunami barrier 1. Both ends are locked to each locking column 21.

The wire rope 31 is formed by, for example, twisting strands obtained by twisting metal wires such as steel. As the wire rope 31, a wire rope that has been subjected to a predetermined load for a certain period of time in advance and reduced in initial elongation before being installed on the tsunami barrier 1 is used. That is, the wire rope 31 used for the tsunami barrier 1 is pre-tensioned.
The diameter (φ) of the wire rope 31 to be used is appropriately selected according to the distance between the tsunami barrier 1 and the protection target T.

<Selection of wire rope>
Hereinafter, selection of the wire rope 31 to be bridged over the tsunami barrier 1 will be described.
When the tsunami barrier 1 must be installed close to the protection target T, only a limited narrow space is secured between the support 2 and the screen 3 and the protection target T. Here, “proximity” is not particularly limited. The interval between the tsunami barrier T and the protection target T is appropriately selected as a design condition of a place where the tsunami barrier 1 is actually installed according to the installation location.
When the tsunami barrier 1 must be installed close to the protection target T, for the wire rope 31 to be used, the displacement amount (mm) of the wire rope 31 and the absorption energy (kJ) required in the tsunami barrier 1 are determined. Choose with consideration. That is, the wire rope 31 to be used is selected in consideration of how much the wire rope 31 is displaced with respect to the maximum (predetermined) absorbed energy required in the design of the tsunami barrier 1.

Table 1 compares various line types that can be used as screens.

  It is desirable that the screen material used has a large elastic modulus and a high yield stress. From Table 1, it can be seen that the PC steel strand has the highest numerical values for both the elastic modulus and the yield stress. However, the locking column 21 must not be deformed before the suspended screen material yields, and the fact that the yield stress of the screen material is large means that the yield stress of the screen material is larger than that of the screen material. Means that the locking column 21 needs to have In order to increase the yield stress of the locking column 21, it is necessary to increase the diameter of the locking column 21. As a result, the workability of the tsunami barrier is reduced and the installation cost is increased.

Therefore, a wire rope having a lower yield stress than a PC steel strand is selected. Thus, it is possible to suppress an increase in the diameter of the locking column 21. However, even if the wire ropes have the same yield stress, the elastic modulus differs depending on the presence or absence of pretension. In other words, the elastic modulus of the pre-tensioned wire rope is larger than the elastic modulus of the non-pre-tensioned wire rope, and the displacement of the pre-tensioned wire rope is This is smaller than the displacement of the wire rope that has not been subjected to tension processing.
Thereby, in the tsunami barrier 1 installed close to the protection target T, it is preferable to select the pre-tensioned wire rope 31.

Next, a displacement suppressing effect of the wire rope according to the present embodiment having various diameters (φ) will be described with reference to FIGS. 3 is a graph showing the effect of suppressing the displacement of the wire rope of φ10, FIG. 4 is a diagram of φ16, FIG. 5 is a diagram of the displacement of the wire rope of φ20, and FIG. 6 is a graph showing the relationship between the absorbed energy (kJ) and the elongation. (B) is a graph showing the relationship between the displacement (mm) and the absorbed energy (kJ).
The trial calculation conditions in FIGS. 3 to 6 are such that the interval between the two locking columns 21 is 50 m and the interval between the columns 2 (the locking column 21 and the supporting columns 22) is 10 m. That is, four support columns 22 are installed at equal intervals between the two locking columns 21.
In addition, in each figure (b), the value of the displacement amount (mm) takes into account the initial tension when the wire rope 31 is hung over the locking column 21.

From the graphs of FIGS. 3 to 6, for example, the absorbed energy (kJ) at the same elongation of the wire rope that has not been subjected to the pretensioning and the wire rope 31 that has been subjected to the pretensioning can be determined by any diameter (φ). Also in the wire rope of (a), the wire rope 31 that has been subjected to the pretension processing is higher than the wire rope that has not been subjected to the pretension processing. That is, the pre-tensioned wire rope 31 can cope with a larger absorbed energy (kJ) even if the elongation is the same as that of the non-pretensioned wire rope 31.
Specifically, in any of the wire ropes of φ10, φ16, φ20, and φ25, the absorbed energy (kJ) of the pretensioned wire rope 31 at an elongation of 0.01 is subjected to the pretensioning. It is about 1.3 times larger than the absorbed energy (kJ) of the unwired wire rope.

Further, from the graphs of FIGS. 3 to 6, for example, 100 kJ, which is the maximum value of the absorbed energy required for the design, of the wire rope that has not been subjected to the pretensioning and the wire rope 31 that has been subjected to the pretensioning. It can be seen that the displacement amount (mm) in the case of (1) is smaller in the wire rope 31 subjected to the pretension processing.
Specifically, in any of the wire ropes of φ10, φ16, φ20, and φ25, for example, the displacement amount (mm) of the wire rope 31 subjected to the pretension processing at the absorption energy of 100 kJ is subjected to the pretension processing. It is about 0.9 times as large as the displacement (mm) of the wire rope that has not been moved.

For example, in the case of the tsunami barrier 1, if the distance between the wire rope and the protection target T is 1200 mm, the wire rope that is selected based on 100 kJ of the required absorbed energy by design is pre-tensioned. In the case of the wire rope 31 used, a wire rope of φ20 may be selected (a displacement amount of 1125 mm).
On the other hand, in the case of a wire rope that has not been subjected to pretensioning, the displacement amount of φ20 is 1218 mm, so that the wire rope may be displaced and come into contact with the protection target T. Therefore, in the case of a wire rope that has not been subjected to pretensioning, a wire rope of φ25 (a displacement amount of 1089 mm) in which the displacement amount is less than 1200 mm when the required absorption energy is 100 kJ must be selected in design. Must.

As described above, as the screen material, the wire rope 31 which is subjected to the pretensioning process in which the displacement amount (mm) is small even with the same absorption energy (kJ) and the absorption energy (kJ) is large even with the same elongation rate is used. Is preferred.
Regarding the diameter (φ) of the wire rope 31, the distance between the wire rope 31 and the protection target T and the displacement (mm) at the maximum absorption energy (kJ) required in terms of design are compared, and the displacement (mm) is determined. mm) is smaller than the distance between the wire rope 31 and the protection target T.

According to the tsunami barrier 1 provided with the wire rope 31 as described above, since the wire rope 31 of the screen 3 is subjected to the pretension processing, the pretension processing having the same diameter (φ) is not performed. Compared to a wire rope, the initial elongation and diameter reduction during use can be suppressed to a small value, and since it has a high elastic modulus, even when the tsunami barrier 1 must be installed close to the protection target T, The wire rope 31 can be prevented from contacting the protection target T.
In other words, even when the distance between the protection target T and the tsunami barrier 1 is close, instead of using a PC steel stranded wire having a high elastic modulus, the screen 3 has a smaller elastic modulus than the PC steel stranded wire. The wire rope 31 is used for the tsunami barrier 1 while suppressing a displacement while securing a sufficient elastic coefficient as described above. As a result, it is possible to suppress an increase in the diameter of the locking strut 21 that locks the wire rope 31, thereby improving workability as a whole and reducing costs as compared with a tsunami barrier using a PC steel stranded wire as a screen. Tsunami barrier 1 can be installed.
Further, since the wire rope 31 is pretensioned, the arrangement of the wires and the like constituting the wire rope 31 is adjusted, and the fatigue resistance is improved.
Furthermore, the wire rope has many options of the diameter (φ) as compared with the PC steel strand, and has many options according to the distance between the protection target T and the tsunami barrier 1.

<Others>
Note that the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the scope of the present invention. For example, in the above embodiment, the tsunami barrier 1 is provided with the screen 3 over the entire circumference. However, the tsunami barrier 1 may be provided with a gate for carrying workers or working equipment for repairing / checking the protection target T or the like. In the gate G, a pair of locking posts 21 is further disposed between the locking posts 21 arranged in the corner C on one side of the tsunami barrier 1, and the screen 3 is hung between the pair of locking posts 21. It is formed so as not to pass.

DESCRIPTION OF SYMBOLS 1 Tsunami barrier 2 Post 21 Locking post 22 Support post 3 Screen 31 Wire rope

Claims (4)

A plurality of columns erected at predetermined intervals on the foundation,
A screen that captures an object that has been bridged between the plurality of columns and that has been washed away by the force of the wave against the object to be protected,
The tsunami barrier, wherein the screen has a pretensioned wire rope. The wire rope absorbs the absorbed energy of the object by deforming,
2. The tsunami barrier according to claim 1, wherein the wire rope bridged between the columns has a displacement amount based on a predetermined absorbed energy smaller than an interval between the wire rope and a protection target. 3.   The tsunami barrier according to claim 1, wherein a yield stress of the wire rope is smaller than a yield stress of the column.   The tsunami barrier according to any one of claims 1 to 3, wherein an interval between the protection target and the wire rope is close to each other.

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