JP2020070540A - Levee reinforcement structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a levee reinforcement structure capable of ensuring structural stability of levee by dispersing forces such as water pressure and earth pressure acting on a steel sheet pile wall. SOLUTION: A first steel sheet pile wall 20 is provided on an upstream side shoulder 12a of the bank 10 or in the vicinity thereof along the continuous direction of the bank 10, and a second steel sheet pile wall is provided on the downstream side shoulder 13a or its vicinity. 25 is provided along the continuous direction of the embankment 10, and at least a part of the plurality of steel sheet piles 20a forming the first steel sheet pile wall 20 has high permeability as compared with the embankment 10. Since the first steel sheet pile wall 20 bears only earth pressure and the second steel sheet pile wall 25 bears earth pressure and water pressure, forces such as water pressure and earth pressure acting on the steel sheet pile wall are dispersed. .. Therefore, the structural stability of the embankment 10 can be ensured. [Selection diagram] Figure 1

Description

  The present invention relates to a levee reinforcement structure.

  In recent years, a large number of river dikes and reservoir ponds have been destroyed due to large-scale earthquakes, and several large-scale earthquakes are expected to occur, so seismic reinforcement of dikes is becoming more important. ..

Based on such a background, a repairing / reinforcing technique for a bank / embankment using a steel sheet pile has been proposed so far (see, for example, Patent Documents 1 and 2).
In the embankment reinforcement structure described in Patent Document 1, at least one row of sheet pile walls having a depth that penetrates the embankment inside the embankment excluding the slope and is deeply embedded in the supporting ground is continuous in the length direction of the embankment. Is installed in the ground to form a embankment, and a structural skeleton composed of the sheet pile wall and the ground closed by the sheet pile wall is formed.
In such a reinforced embankment structure, at least one row of sheet pile walls penetrates the embankment at a position excluding the slope and is embedded in the support ground, so that the inside of the embankment has two or more sections in the width direction. Since it is divided into parts, groundwater and seepage water are prevented from penetrating the entire width of the embankment, and stability of the structural skeleton itself even when the foundation ground is destabilized by external force during a flood or earthquake. Is secured.

Further, in the embankment reinforcement structure described in Patent Document 2, a sheet pile wall having a higher water blocking capacity than the embankment board constituting the embankment is placed near the embankment side embankment of the embankment, and the embankment side embossment of the embankment. A sheet pile wall having a higher water permeability than that of the sheet pile wall having a high waterproofness is placed in the vicinity, and both sheet pile walls are horizontally connected by a connecting member.
In such a levee reinforcement structure, a sheet pile wall, which has a higher water blocking capacity than the embankment that constitutes the levee, is placed on the river side of the levee to prevent water intrusion and water permeation from the river side and prevent flooding. It is possible to prevent damage to the embankment structure due to external force during a earthquake or earthquake. Also, by placing a sheet pile wall with higher water permeability than the sheet pile wall with high water shuttability on the private side of the embankment, water accumulated in the core portion can be quickly discharged, so that water channel formation and core portion Can be prevented from sinking.

JP, 2003-13451, A JP, 2010-24745, A

By the way, one of the characteristics of levee in reservoirs and rivers is that a certain amount of water exists on one side of the levee, and water pressure acts on the levee from the upstream side at all times and at the time of an earthquake.
However, general steel sheet pile has a high water impermeability, and in the above-mentioned conventional technology, the water pressure acting on the embankment and the sheet pile wall from the stored water is borne by only the sheet pile wall on the upstream side, and the sheet pile wall on the upstream side bears the water pressure. There is a possibility that stress or displacement will occur due to an excessive force acting on the side sheet pile wall.
Further, the sheet pile walls are connected by a tension member generally called a tie rod, but since the water pressure described above acts in a direction of deforming the sheet pile wall on the upstream side to the downstream side, a compressive force acts on the tie rods and each sheet pile wall is There is a possibility that the structural performance required for each row of sheet pile walls will not behave in an interlocking manner and the structural performance required will be excessive.

  The present invention has been made in view of the above circumstances, and by dispersing the force such as water pressure or earth pressure acting on the steel sheet pile wall, the structural stability of the embankment can be ensured and required for the steel sheet pile wall. It is an object of the present invention to provide a levee reinforcement structure that can prevent structural performance from becoming excessive.

In order to achieve the above object, the embankment reinforcement structure of the present invention is a continuous embankment reinforcement structure,
Assuming that the side where water is present is the upstream side and the side opposite to the upstream side is the downstream side, with the top of the embankment in between,
A first steel sheet pile wall is provided on the upstream shoulder of the embankment or in the vicinity thereof along the continuous direction of the embankment,
A second steel sheet pile wall is provided in the downstream shoulder of the embankment or in the vicinity thereof along the continuous direction of the embankment,
At least a part of the plurality of steel sheet piles constituting the first steel sheet pile wall has high water permeability as compared with the embankment.

  Here, "at least a part of the plurality of steel sheet piles configuring the first steel sheet pile wall has higher water permeability than the embankment" constitutes the first steel sheet pile wall. When at least one of the plurality of steel sheet piles has a high water permeability as a whole, at least a part of the plurality of steel sheet piles has a high water permeability. In this case, it further includes the case where all the steel sheet piles constituting the first steel sheet pile wall have high water permeability.

In the present invention, at least a part of the plurality of steel sheet piles constituting the first steel sheet pile wall provided on the upstream side shoulder of the embankment or in the vicinity thereof has high water permeability as compared with the embankment. Therefore, at least part of the water that has permeated the levee from the upstream side passes through the steel sheet pile with high permeability inside the levee, and the second shoulder provided on or near the downstream shoulder of the levee. Reach the steel sheet pile wall.
Therefore, the first steel sheet pile wall bears only earth pressure, and the second steel sheet pile wall bears earth pressure and water pressure, so that the forces such as water pressure and earth pressure acting on the steel sheet pile wall are dispersed. .. Therefore, the structural performances required for the first steel sheet pile wall and the second steel sheet pile wall are almost the same, and the structural performances required for the steel sheet pile wall (the first steel sheet pile wall and the second steel sheet pile wall) are excessive. And the structural stability of the embankment can be secured.

  Moreover, in the said structure of this invention, the said 1st steel sheet pile wall and the said 2nd steel sheet pile wall may be connected by the connection material.

  According to such a configuration, since the first steel sheet pile wall and the second steel sheet pile wall are connected by the connecting member, water pressure and earth pressure act on the second steel sheet pile wall to cause the second steel sheet pile wall. When the wall tries to deform toward the downstream side of the embankment, the tensile force is transmitted to the first steel sheet pile wall through the connecting member, and the first steel sheet pile wall pulls the second steel sheet pile wall. As a result, the first steel sheet pile wall and the second steel sheet pile wall can be interlocked to resist the earth pressure (earth pressure and water pressure). Therefore, the structural stability of the embankment can be reliably ensured.

  Moreover, in the said structure of this invention, as for the said 1st steel sheet pile wall, the part below a design flood level may have high water permeability compared with the said bank.

  Here, the design flood level refers to the maximum water level immediately upstream of the embankment when the design flood discharge flows down the spillway.

  According to such a configuration, since the first steel sheet pile wall has a higher water permeability than the dike in the portion below the design flood level, all of the first steel sheet pile wall has a high water permeability. Therefore, it is possible to omit the process for making the portion above the design flood level highly permeable.

  ADVANTAGE OF THE INVENTION According to this invention, the structure stability of an embankment can be ensured and the steel sheet pile wall is requested | required by dispersing the force of water pressure, earth pressure, etc. which act on a 1st steel sheet pile wall and a 2nd high sheet pile wall. It is possible to suppress the structural performance from becoming excessive.

1A and 1B show a levee reinforcement structure according to an embodiment of the present invention, in which FIG. 1A is a cross-sectional view and FIG. The same is a perspective view showing a part of the first steel sheet pile wall. The distribution of the load which acts on the steel sheet pile wall of the embankment is shown, (a) is a transverse sectional view of the embankment showing the load distribution according to the present embodiment, and (b) is a transverse sectional view of the embankment showing the conventional load distribution. Is.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1A and 1B show a levee reinforcement structure according to the present embodiment. FIG. 1A is a cross-sectional view and FIG. 1B is a plan view.
In the present embodiment, the bank 10 is continuously provided in the direction orthogonal to the paper surface in FIG. 1A, and vertically in FIG. 1B. If the left side is the upstream side and the right side is the downstream side across the top end 11 of the bank 10, the water W exists on the upstream side. Therefore, the levee 10 constitutes a reservoir levee, a river levee, a coastal levee, etc., but in the present embodiment, it constitutes a reservoir levee.

The embankment 10 is provided with a slope 12 on the upstream side and a slope 13 on the downstream side across the crown 11. Although the slope angles of the slopes 12 and 13 with respect to the ground surface GS are equal, the slope angles of the slope 12 and the slope 13 may be different.
In addition, the first steel sheet pile wall 20 is provided in the upstream shoulder 12a of the embankment 10 or in the vicinity thereof in the continuous direction of the embankment 10 (the direction orthogonal to the paper surface in FIG. 1A, the vertical direction in FIG. 1B). It is provided along.
The first steel sheet pile wall 20 is formed by connecting a plurality of steel sheet piles 20a in the continuous direction of the embankment 10. The steel sheet pile 20a strikes the embankment 10 substantially vertically from the upstream shoulder 12a or its vicinity. It is formed by being installed and connected to the steel sheet pile 20a that was previously placed. Further, the lower end portion of the first steel sheet pile wall 20 penetrates the embankment 10 and reaches the ground G.

In addition, at least a part of the plurality of steel sheet piles 20a forming the first steel sheet pile wall 20 has a higher water permeability than the embankment forming the embankment 10.
For example, when the steel sheet pile 20a has a hat shape, as shown in FIG. 1A, the embankment 10 is configured by providing a plurality (a large number) of water-permeable holes 20b in the web of the steel sheet pile 20a at predetermined intervals in the vertical and horizontal directions. The steel sheet pile 20a has higher water permeability than the embankment.
And the 1st steel sheet pile wall 20 may be comprised entirely by the steel sheet pile 20a with high water permeability, and a part may be comprised by the steel sheet pile 20a with high water permeability. When part of the steel sheet pile 20a having high water permeability is provided, a water permeable hole 20b is provided at least in a portion of the steel sheet pile 20a located above the ground surface GS and inside the embankment 10 and is located below the ground surface GS. The water-permeable holes 20b may or may not be provided in the portion of the steel sheet pile 20a.

  Further, the first steel sheet pile wall 20 preferably has a water permeability higher than that of the embankment 10 at a portion below the design flood level HWL. The design flood level HWL is the maximum water level immediately upstream of the embankment when the design flood flow flows down the spillway, so even if the water penetration hole 20b is provided above this water level (design flood level), It is almost impossible to escape the water that has penetrated into the embankment 10 through the water holes 20b. For this reason, specifically, in the steel sheet pile 20a that constitutes the first steel sheet pile wall 20, it is preferable that the water passage hole 20b is provided at a portion below the design flood level HWL and the water passage hole 20b is not provided at an upper portion. ..

Further, a second steel sheet pile wall 25 is provided in the downstream shoulder 13a of the embankment 10 or in the vicinity thereof along the continuous direction of the embankment 10.
The second steel sheet pile wall 25 is formed by connecting a plurality of steel sheet piles 25a in the continuous direction of the embankment 10, and strikes the steel sheet pile 25a on the embankment 10 substantially vertically from the downstream side shoulder 13a or its vicinity. It is formed by being installed and connected to the steel sheet pile 25a that was previously placed. Further, the lower end portion of the second steel sheet pile wall 25 penetrates the embankment 10 and reaches the ground G. Moreover, unlike the first steel sheet pile wall 20, the second steel sheet pile wall 25 has water impermeability. In other words, the water perforation holes are not provided in the plurality of steel sheet piles 25a forming the second steel sheet pile wall 25.
Further, the driving depth of the second steel sheet pile wall 25 into the ground is equal to the driving depth of the first steel sheet pile wall 20 into the ground, but may be different.

  Further, the water that has permeated the levee 10 from the reservoir passes through the water permeation holes 20b of the first steel sheet pile wall 20 and is stored in the core portion of the levee 10 between the first steel sheet pile wall 20 and the second steel sheet pile wall 25. Therefore, the water level WL inside the embankment 10 is lowered as a whole. That is, when the water penetration hole 20b is not provided in the 1st steel sheet pile wall 20, since the water which permeated the embankment 10 from a reservoir is dammed up by the 1st steel sheet pile wall 20, it is upstream of the said 1st steel sheet pile wall 20. Although the water level inside the embankment 10 becomes high, since at least a part of the water that has penetrated from the reservoir to the embankment 10 is stored in the core portion by providing the water perforation holes 20b in the first steel sheet pile wall 20, The water level WL inside the embankment 10 is lowered as a whole.

The first steel sheet pile wall 20 and the second steel sheet pile wall 25 are connected by a connecting material (tensile material) 27 such as a tie rod or a wire.
That is, the upper end of the first steel sheet pile wall 20 and the upper end of the second steel sheet pile wall 25 are connected by the connecting member 27 on the surface of the top end 11 of the embankment 10 or slightly below the surface. A plurality of the connecting members 27 are arranged at predetermined intervals in the continuous direction of the embankment 10 (direction orthogonal to the paper surface in FIG. 1), and one end of each connecting member 27 is at the upper end of the first steel sheet pile wall 20. It is fixed and the other end is fixed to the upper end of the second steel sheet pile wall 25.
Therefore, when water pressure and earth pressure act on the second steel sheet pile wall 25 and the second steel sheet pile wall 25 tries to deform toward the downstream side of the embankment 10, a tensile force is exerted through the connecting member 27 on the first steel sheet pile. It is transmitted to the wall 20. As a result, the deformation of the second steel sheet pile wall 25 is suppressed by the first steel sheet pile wall 20, so that the first steel sheet pile wall 20 and the second steel sheet pile wall 25 are interlocked with each other to reduce the soil water pressure (earth pressure and water pressure). It becomes possible to resist.
The first steel sheet pile wall 20 and the second steel sheet pile wall 25 do not necessarily have to be connected by the connecting member 27, and the scale and strength of the embankment 10, the first steel sheet pile wall 25, and the second steel sheet pile wall 27. It can be appropriately determined depending on the strength and the like.

  In the reinforcement structure of the embankment of the present embodiment, the portion of the first steel sheet pile wall 20 below the design flood level HWL has a higher water permeability than the embankment 10, so that the reservoir changes from the embankment 10 to the embankment 10. The permeated water passes through the water-permeable holes 20b of the first steel sheet pile wall 20 and reaches the second steel sheet pile wall 25. Therefore, as shown in FIG. 2A, both the water pressure and the earth pressure act on the second steel sheet pile wall 25, and the load distribution is the load distribution obtained by adding the load increase by the water pressure to the load by the earth pressure. ..

  On the other hand, in the conventional embankment reinforcement structure, the first steel sheet pile wall 20 does not have the water permeation holes 20b and has water impermeability, so that the water that has penetrated from the reservoir to the embankment 10 is 1 It cannot pass through the steel sheet pile wall 20. Therefore, the water pressure is to be borne only by the first steel sheet pile wall 20, and the first steel sheet pile wall 20 also bears the earth pressure, so that the first steel sheet pile wall 20 has the second steel sheet. An excessive force acts on the sheet pile wall 25. That is, as shown in FIG. 2B, both the water pressure and the earth pressure act on the first steel sheet pile wall 20, and the load distribution is the load distribution obtained by adding the load increase by the water pressure to the load by the earth pressure. ..

  Moreover, since the 1st steel sheet pile wall 20 and the 2nd steel sheet pile wall 25 are connected by the connection material 27, the water pressure and earth pressure act on the 2nd steel sheet pile wall 25, and the said 2nd steel sheet pile wall 25 concerned. Deforms toward the downstream side of the embankment 10, and a tensile force is generated in the connecting material 27. Therefore, the first steel sheet pile wall 20 and the second steel sheet pile wall 25 can interlock with each other to resist the earth pressure (earth pressure and water pressure).

  Therefore, according to the present embodiment, the first steel sheet pile wall 20 bears only earth pressure, and the second steel sheet pile wall 25 bears earth pressure and water pressure. Forces such as water pressure and earth pressure acting on the sheet pile wall 20 and the second steel sheet pile wall 25) are dispersed. Therefore, the structural performances required for the first steel sheet pile wall 20 and the second steel sheet pile wall 25 are substantially the same, and are required for the steel sheet pile wall (the first steel sheet pile wall 20 and the second steel sheet pile wall 25). It is possible to prevent the structural performance from becoming excessive and to secure the structural stability of the embankment 10.

Further, in the first steel sheet pile wall 20, the portion below the design flood level HWL has higher water permeability than the embankment 10, so the portion above the design flood level HWL has high water permeability. Processing for can be omitted.
The water that has permeated the levee 10 from the reservoir passes through the water permeation holes 20b of the first steel sheet pile wall 20 and is stored in the core portion of the levee 10 between the first steel sheet pile wall 20 and the second steel sheet pile wall 25. Therefore, the water level inside the bank 10 is lowered as a whole, and as a result, the bank breakage prevention effect of the bank 10 can be achieved.

10 Embankment 11 Top end 12a Upstream side shoulder 13a Downstream side shoulder 20 First steel sheet pile wall 20a Steel sheet pile 25 Second steel sheet pile wall 25a Steel sheet pile 27 Connecting material HWL Design flood level

Claims (3)

Reinforcement structure of continuous levees,
Assuming that the side where water is present is the upstream side and the side opposite to the upstream side is the downstream side, with the top of the embankment in between,
A first steel sheet pile wall is provided on the upstream shoulder of the embankment or in the vicinity thereof along the continuous direction of the embankment,
A second steel sheet pile wall is provided in the downstream shoulder of the embankment or in the vicinity thereof along the continuous direction of the embankment,
At least a part of the plurality of steel sheet piles constituting the first steel sheet pile wall has a higher water permeability than the levees, and a levee reinforcement structure.   The embankment reinforcement structure according to claim 1, wherein the first steel sheet pile wall and the second steel sheet pile wall are connected by a connecting member.   The reinforcement structure of the embankment according to claim 1 or 2, wherein a portion of the first steel sheet pile wall below the design flood level has a higher water permeability than the embankment.

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