JP7183819B2 - Levee body seepage failure prevention structure - Google Patents

Description

The present invention relates to a seepage failure prevention structure for a bank body.

In recent years, there have been many breaches of river levees and reservoir levees due to large-scale earthquakes, and since several large-scale earthquakes are expected to occur, seismic reinforcement of levees is becoming increasingly important. .

Against this background, techniques for reinforcing embankments (embankment bodies) using steel sheet piles have been proposed (for example, see Patent Documents 1 to 3).
In the seismic performance reinforcing structure of the embankment described in Patent Document 1, reinforcing plate-like bodies formed of steel sheet piles in two rows and columns in the longitudinal direction of the almost central part of the embankment such as an earthfill dam or a reservoir are installed. A double coffer structure is formed in which the upper ends of both reinforcing plates are connected by a connecting member at predetermined intervals.

In addition, in the embankment reinforcement structure described in Patent Document 2, one or more rows of underground steel walls are provided along the continuous direction of the embankment within the range of the top end of the continuous embankment, and the embankment A diagonal member is provided on at least one of the slopes so as to protect the slope so that it becomes lower as it moves away from the top of the embankment, and the lower part of the diagonal member is lower than the embankment. It is cast into the ground.

Further, in the embankment reinforcement structure described in Patent Document 3, a first suppressing member and a second suppressing member provided along the first slope and the second slope of the embankment, and the first suppressing member and a plurality of connecting members that connect the second restraining member, wherein the first restraining member and the second restraining member are arranged on the first slope surface and the second slope surface It has a slope portion and an embedded portion that is embedded in the ground, and the slope portion and the embedded portion are formed continuously in a substantially straight line.

JP-A-2003-321826 JP 2011-214254 A JP 2015-221994 A

By the way, "Trans. of JSIDRE No.218, Journal of the Japan Society of Agricultural
127-137 (2002.4), ``Causes of Destruction of Agricultural Ponds by Heavy Rain and Characteristics of Damage'', it is said that there are about 200,000 to 250,000 agricultural reservoirs nationwide. It is a valuable water resource not only for agriculture but also for the region. However, there are many ponds because they were built long ago and have deteriorated, and there are concerns about damage to the ponds during heavy rains. Damage to reservoirs includes damage to the embankment due to slips and erosion, water leakage from the embankment and foundation, and damage to incidental structures. It's becoming
Seepage failure is said to be the most common cause of damage to the bank of a reservoir during heavy rain. This seepage failure occurs because the upstream slope on the reservoir side (reservoir side or upstream side) of the upper part of the embankment from the full water level always becomes a leak entrance to the inside of the embankment that causes seepage failure. On the upstream slope of the cut-off wall, the ground strength of the cut-off wall decreased due to repeated dryness and wetness due to the up-and-down movement of the reservoir water level, the suction of soil particles to the reservoir side, and erosion caused by waves for a long period of time. may cause local destruction.

On the other hand, in the seismic performance reinforcing structure of the embankment described in Patent Document 1, the reinforcing plate-like bodies are embedded in two rows and columns in the longitudinal direction of the almost central part of the embankment, and the upper ends of the reinforcing plate-like bodies Although the sections are connected by connecting members at predetermined intervals, it is not possible to prevent permeation from the upstream slope, which is the starting point of permeation failure.
In addition, in the embankment reinforcement structure described in Patent Document 2, if diagonal members are provided to protect the downstream slope, the embankment slope may collapse or the ground may be scoured due to overflow during flooding. It does not act as a protective method against seepage failure. A case where diagonal members are installed on the upstream slope is also shown, but it is necessary to drive the diagonal members into the ground below the levee body, which obstructs the water flow at the bottom of the levee body and affects the water environment. will give
In addition, in the embankment reinforcement structure described in Patent Document 3, in order to protect the slope, restraining members are provided along two slopes on both sides of the bank body, and the two restraining members are fastened with a plurality of connecting members. Since it is necessary to embed a connecting member inside the body, or it is necessary to reinforce along two slopes, the reinforcing structure becomes large, and the construction cost and construction period increase.

The present invention has been made in view of the above circumstances. The purpose is to provide a seepage failure prevention structure for embankments that can shorten construction costs and construction periods by specializing in the prevention of seepage failure at times.

In order to achieve the above object, the seepage failure prevention structure for the embankment of the present invention is a seepage failure prevention structure for the embankment provided on at least a part of the outer circumference of the reservoir for preventing seepage failure of the embankment,
Assuming that the reservoir side is the upstream side across the bank, a steel wall is provided on the upstream slope of the bank on the upstream side and at or near a full water position at a height equal to the full water level of the reservoir. is installed so as to protrude upward along the extending direction of the bank body,
A protection part is provided to protect the upstream slope above the full water position or its vicinity,
The protection part is a filling-type permeation prevention part made of a water-impermeable material filled between the steel wall and the upstream slope.

Here, as the steel wall, a steel sheet pile wall formed by connecting a plurality of steel sheet piles is suitably used, but it is not limited to this. For example, a steel pipe sheet pile wall formed by connecting a plurality of steel pipe sheet piles, a steel wall formed by connecting a plurality of steel sheet piles and steel pipe sheet piles, or the like may be used.
Also, the term "nearby" means a range within 1 m in the vertical direction from the full-water position on the upstream slope.
In addition, examples of the "filled permeation preventive part made of a water-impermeable material" include, but are not limited to, a filled preventive part made of blade metal clay, soil cement, or bentonite.

In the present invention, a steel wall protrudes upward along the extending direction of the embankment at or near the full water position at the upstream slope of the embankment and at a height equal to the full water level of the reservoir. and is provided with a protective portion that protects the upstream slope above the full water position or its vicinity, and the protective portion is made of a water-impermeable material filled between the steel wall and the upstream slope Since it is a filling type seepage prevention part, this filling type seepage prevention part can prevent seepage at the time of high water on the upstream slope, which is the starting point of seepage failure, and can suppress seepage failure of the embankment.
In addition, since the filling type seepage prevention part is provided by filling impermeable material between the steel wall and the upstream slope of the embankment, it is not necessary to protect the entire slope. can shorten the construction cost and construction period.

Further, another embankment seepage failure prevention structure of the present invention is a embankment seepage failure prevention structure for preventing seepage failure of an embankment provided at least part of the outer periphery of a reservoir,
Assuming that the reservoir side is the upstream side across the bank, a steel wall is provided on the upstream slope of the bank on the upstream side and at or near a full water position at a height equal to the full water level of the reservoir. is installed so as to protrude upward along the extending direction of the bank body,
A protection part is provided to protect the upstream slope above the full water position or its vicinity,
The protection part includes a surface type permeation prevention part made of a water impermeable material provided along the upstream slope above the full water position or its vicinity, and a surface type permeation prevention part made of the steel wall and the surface type permeation prevention part. It is characterized by having a filling-type permeation prevention part made of a water-impermeable material filled between them.

Here, the "surface type permeation prevention part made of impermeable material" includes, for example, concrete blocks installed on the upstream slope, sprayed concrete constructed on the upstream slope, and impermeable material covering the upstream slope. Examples include sheets and geotextiles, but are not limited to these.

In the present invention, the protection part comprises a surface type permeation prevention part made of a water impermeable material provided along the upstream slope above the full water position or its vicinity, the steel wall and the surface type Since it has a filling type seepage preventive part made of a water impermeable material filled between the seepage preventive part and the seepage preventive part, it prevents seepage at the time of high water on the upstream slope that is the starting point of seepage failure, and seepage failure of the embankment body. can be suppressed. In addition, when only the surface type penetration prevention part is installed on the upstream slope, the surface type penetration prevention part may be peeled off from the upstream slope by the water flow. By covering and protecting the upper side of the permeation prevention part, the surface permeation prevention part can be firmly fixed at the upstream slope position.
In addition, the surface type penetration prevention part is provided along the upstream slope, and the filling type penetration prevention part is provided by filling a water-impermeable material between the steel wall and the surface type penetration prevention part, There is no need to protect the entire slope surface, and the construction cost and construction period can be shortened compared to conventional methods.

Further, in the configuration of the present invention, the upper end of the steel wall, the upper surface of the filling type permeation prevention portion, and the top end of the bank may be integrally paved.
In addition, when a surface type seepage preventive part is provided on the upstream slope of the bank, the upper end of the steel wall, the upper surface of the filling type seepage preventive part, and the top of the bank body, including the upper end of this surface type seepage preventive part may be integrally paved.

According to such a configuration, since the upper end of the steel wall, the upper surface of the filling type seepage prevention part, and the top of the embankment are integrally paved, the upstream slope from the top of the embankment due to overflow water, It is possible to prevent water leakage into the embankment.

Further, in the configuration of the present invention, the lower end of the steel wall is located below the full-water position and is supported by a support member installed below the lower end of the steel wall,
The support member may be a plurality of steel members provided at predetermined intervals in the extending direction of the steel wall, or a water-permeable steel wall extending in the extending direction of the steel wall.

According to such a configuration, the steel wall is installed at the position where the upstream slope and the normal full water level intersect, so that the amount of water stored in the entire reservoir is not reduced. Furthermore, since the lower end of the steel wall is supported by a support member consisting of a plurality of steel members or permeable steel walls installed below the lower end, the steel wall can be reliably installed, The groundwater flow in the levee body and in the soft layer directly below the levee body is not hindered.

Further, in the configuration of the present invention, a structure extending in the width direction of the bank is provided inside the bank,
When the support member is a plurality of steel members provided at predetermined intervals in the extending direction of the steel wall, the steel member is installed at a position avoiding the structure,
When the support member is a permeable steel wall extending in the direction in which the steel wall extends, one of the plurality of steel sheet piles constituting the permeable steel wall is located above the structure. The lower end of the steel sheet pile does not have to reach the structure.

Here, the structure provided inside the embankment includes a bottom gutter, but is not limited to this.

According to such a configuration, it is possible to prevent the structure from being damaged by the steel member or the permeable steel wall installed inside the bank body interfering with the structure.

According to the present invention, since it specializes in a reinforcement construction method that suppresses seepage failure of the embankment provided around the reservoir, the construction cost and construction period can be shortened compared to the conventional construction method that reinforces the entire embankment.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional view which shows the seepage failure prevention structure of the embankment which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the seepage failure of a bank body. 1 is a perspective view showing a steel sheet pile wall of a first example, which shows a seepage failure prevention structure for a bank according to the first embodiment of the present invention. FIG. It is sectional drawing which shows the state which installed the steel sheet pile wall of a 1st example equally. It is a perspective view which shows the steel sheet pile wall of a 2nd example same. It is sectional drawing which shows the state which installed the steel sheet pile wall of a 2nd example equally. FIG. 5 is a cross-sectional view showing a seepage failure prevention structure for embankments according to a second embodiment of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing a seepage failure prevention structure for a bank body according to a first embodiment.
First, seepage failure of a bank body will be described with reference to FIG.

As shown in FIG. 2, the path of seepage failure is the path from the full water level to the upper upstream slope, flowing down a relatively shallow portion of the bank, and reaching the downstream slope.
A hole with a diameter of several centimeters and a depth of several tens of centimeters is often observed near the slope upstream of the high water level. Such holes were not created in a short period of time, but were thought to have occurred over a long period of time due to the repetition of dryness and wetness caused by fluctuations in the water level, the suction of soil particles to the water storage side, and erosion caused by waves. Such erosion for a long period of time reduces the ground strength of the embankment, and when water pressure acts on the upstream slope due to a rise in the water level during heavy rains, etc., the above-mentioned hole becomes a leak entrance into the embankment and the downstream slope. If there is a bottom gutter near the foundation ground, especially in the vicinity, it becomes a structural change point in the embankment body, and uneven settlement is likely to occur, and it is likely to become a water supply. As a method of repairing the upstream slope that serves as an infiltration entrance, concrete blocks, etc., are sometimes laid on the surface of the spot. When the body collapses, the concrete blocks may flow out together with the embankment, making it impossible to maintain the crest height of the embankment.

Therefore, in the present embodiment, the following seepage destruction prevention structure is adopted.
First, in the present embodiment, in a plan view (not shown), the bank body 10 surrounds the periphery of the reservoir 11, but the bank body 10 may be provided on at least part of the periphery of the reservoir.
In this case, the portion where the embankment body 10 is not provided is formed by the existing ground such as natural ground and by a protrusion having a height equal to or higher than the embankment body. Therefore, the outer circumference of the reservoir is surrounded by the soil structure formed by the bank and the projecting portion. An earthen structure is a structure basically formed mainly of earth, and includes those provided with various facilities and articles made of concrete or the like inside or on the surface thereof.

Further, as shown in FIG. 1 , there is a soft layer 30 directly below the embankment body 10 , and a support layer 40 or bedrock layer is directly below the soft layer 30 . The soft layer 30 and the support layer 40 are also continuous below the reservoir 11 .
In the present embodiment, the embankment body 10 is provided on the upper surface of the soft layer 30 .

Further, if the reservoir 11 side (inner side) of the embankment body 10 is defined as the upstream side and the outer side is defined as the downstream side, the reservoir 11 exists because water is stored on the upstream side. In addition, the bank body 10 has an upstream slope 10b on the upstream side and a downstream slope 10c on the downstream side across the crest 10a. The inclination angles of the upstream slope 10b and the downstream slope 10c with respect to the ground surface (upper surface of the soft layer 30) are equal, but the inclination angles may be different between the upstream slope 10b and the downstream slope 10c.

In addition, a steel sheet pile wall (steel wall) 15a is installed so as to protrude upward at or near a full water position 12 at a height equal to the full water level of the reservoir 11 on the upstream slope 10b of the bank body 10. there is
In addition, the lower end of the steel sheet pile wall 15a is positioned inside the bank body 10 about 1 m below the full-water position 12 . The lower end position of the steel sheet pile wall 15a may be aligned with the full water position, but there may be a construction error in the driving depth direction of the steel sheet pile wall 15a, or the slope height position may change due to fluctuations in the reservoir level or weathering. Considering that fluctuations may occur, in order to reliably protect the filling type seepage prevention part with the steel sheet pile wall at a height above the full water position, the lower end of the steel sheet pile wall 15a is about 1 m or more, and the bank body 10 It is preferable to keep it rooted inside.
A lower end of the steel sheet pile wall 15a is supported by a support member 18 installed below the lower end.

There are two examples of the support member 18, for example. The support member 18 of the first example is a permeable steel sheet pile wall (permeable steel wall) 15b.
As shown in FIGS. 3 and 4, the permeable steel sheet pile wall 15b and the steel sheet pile wall 15a constitute a steel sheet pile wall 15 integrally formed.
First, the steel sheet pile wall 15 is formed by connecting a plurality of hat-shaped steel sheet piles 16 .
The steel sheet pile 16 includes a web 16a, flanges 16b formed at both ends of the web 16a, and an arm 16c formed at the end of the flange 16b opposite to the web 16a. A joint 16d is formed in the portion.
Adjacent steel sheet piles 16, 16 are connected by fitting joints 16d, 16d to each other, whereby a steel sheet pile wall 15 is formed.

The web 16a is integrally formed by an upper web 16a1 and a lower web 16a2, and the lower web 16a2 is provided with a plurality (a large number) of elliptical or circular water permeable holes 17 vertically and horizontally at predetermined intervals. The upper web 16a1 is not provided with the water permeable holes 17. As shown in FIG.
The lower portion having the lower web 16a2 provided with the permeable holes 17 is the permeable steel sheet pile wall 15b, and the upper portion having the upper web 16a1 is the steel sheet pile wall 15a.

Although the steel sheet pile wall 15a and the permeable steel sheet pile wall 15b are integrally formed, they may be formed separately and connected by welding or the like.
The steel sheet piles forming the steel sheet pile wall 15 are not limited to hat-shaped steel sheet piles, and may be U-shaped steel sheet piles or straight steel sheet piles.

5 and 6, a second example of the support member 18 is a plurality of steel members provided at predetermined intervals in the extending direction of the steel sheet pile wall 15a (horizontal direction in FIGS. 5 and 6). (Steel sheet pile) 15c, and the steel sheet pile wall 15 is configured by the steel sheet pile wall 15a and the steel member 15c. That is, the steel sheet pile wall 15a and the steel member 15c are formed to have the same cross section and are vertically continuous.
The steel sheet pile wall 15 is formed by connecting a plurality of hat-shaped steel sheet piles 16 as in the first example described above.
The steel sheet pile 16 includes a web 16a, flanges 16b formed at both ends of the web 16a, and an arm 16c formed at the end of the flange 16b opposite to the web 16a. A joint 16d is formed in the portion.
Adjacent steel sheet piles 16, 16 are connected by fitting joints 16d, 16d to each other, whereby a steel sheet pile wall 15 is formed.

Among the plurality of steel sheet piles 16 constituting such a steel sheet pile wall 15, a predetermined steel sheet pile 16 has a longer dimension in the vertical direction than the other steel sheet piles 16, and protrudes downward. The protruding portion becomes the steel member 15c and supports the steel sheet pile wall 15a from below. Such steel members 15c are integrally formed with the steel sheet pile wall 15a, and are provided in plurality at predetermined intervals in the extending direction of the steel sheet pile wall 15a.

Although the steel sheet pile wall 15a and the steel member 15c are integrally formed, they may be formed separately and connected by welding or the like. It is not limited to steel sheet piles, and may be steel sheet piles of other shapes, steel pipe sheet piles, or the like.
The steel sheet piles forming the steel sheet pile wall 15 are not limited to hat-shaped steel sheet piles, and may be U-shaped steel sheet piles or straight steel sheet piles.

As shown in FIG. 1, the steel sheet pile wall 15 having such a structure is installed vertically at or near the full water position 12 at the upstream slope 10b of the bank 10 and at a height equal to the normal full water level of the reservoir 11. The upper steel sheet pile wall 15a protrudes upward from the full water position 12, and the lower end of the steel sheet pile wall 15a is positioned about 1 m below the full water position 12.
The lower end of the steel sheet pile wall 15a is supported by the permeable steel sheet pile wall 15b or the steel member 15c, which is the lower supporting member 18, and the lower end of the permeable steel sheet pile wall 15b or the steel member 15c forms the soft layer 30. It penetrates and abuts or is close to the upper surface of the support layer 40 immediately below it, but may be embedded in the support layer 40 .
In addition, in FIG. 1, the case where the support member 18 is the permeable steel sheet pile wall 15b is shown.

Moreover, the upstream slope 10b above the full-water position 12 of the bank body 10 or the vicinity thereof is protected by the protection portion 20 .
The protection part 20 is a filling type permeation prevention part 21 made of a water-impermeable material filled in the space between the steel sheet pile wall 15a and the upstream slope 10b. As the impermeable material, hagane clay, soil cement, bentonite, or the like is preferably used, but the material is not limited to these. Such a filling type permeation prevention part 21 is formed in a right-angled triangular cross section, and is in close contact with the surface of the steel sheet pile wall 15a facing the embankment body 10 side and the upstream slope 10b.

In addition, the upper end of the steel sheet pile wall 15a, the upper surface of the filling type penetration prevention part 21, and the top end 10a of the bank body 10 are at almost the same height position, and the upper end of the steel sheet pile wall 15a, the filling type penetration prevention part 21 The top surface and the crest 10a of the bank body 10 are integrally paved to form a paved portion 22. - 特許庁The paved portion 22 has a predetermined thickness and its upper surface is formed substantially horizontally. Pavement materials used for pavement include concrete, asphalt, and the like, but are not limited to these.

Further, as shown in FIG. 6, a structure 25 such as a bottom gutter extending in the width direction perpendicular to the extending direction of the bank 10 (the direction perpendicular to the paper surface in FIG. 6) is provided at the bottom of the bank 10. is provided and the support member 18 is a plurality of steel members 15c provided at predetermined intervals in the extending direction of the steel sheet pile wall 15a, the steel members 15c support the structure 25 placed in an avoidance position. In addition, the water taken in from the water intake hole of the slanted sluice pipe buried along the upstream slope 10b of the embankment body 10 is led to the bottom gutter and taken in.

Further, as shown in FIG. 4, a structure 25 such as a bottom gutter extending in the width direction perpendicular to the extending direction of the bank 10 (the direction perpendicular to the paper surface in FIG. 4) is provided at the bottom of the bank 10. is provided and when the support member 18 is the permeable steel sheet pile wall 15b, among the plurality of steel sheet piles 16 constituting the permeable steel sheet pile wall 15b, the position above the structure 25 The lower end of the steel sheet pile 16 does not reach the structure 25 and is close to the structure 25 .

As described above, according to the present embodiment, the steel sheet pile wall 15a of the bank body 10 is located at or near the full water position 12 at the upstream slope 10b of the bank body 10 and at a height equal to the full water level of the reservoir 11. A protective portion 20 is provided along the extending direction and protruding upward to protect the upstream slope 10b above the full water position 12 or its vicinity, and the protective portion 20 is provided with the steel sheet pile wall 15a. Since the filling type permeation prevention part 21 is made of a water-impermeable material filled between the upstream slope 10b, the filling type permeation prevention part 21 prevents the upstream slope 10b, which is the starting point of permeation destruction, from rising water. can be prevented from permeating, and permeation destruction of the bank body 10 can be suppressed. As a result, it is possible to prevent sliding failure in which the upper part of the bank body 10 collapses along the seepage failure surface in the bank body.
In addition, since the filling type permeation prevention part 21 is provided by filling a water-impermeable material between the steel sheet pile wall 15a and the upstream slope 10b of the bank 10, the bank 10 is excavated and deteriorated. It eliminates the need for large-scale earthwork such as replacing ground materials or injecting chemicals to harden the ground, making it possible to shorten construction costs and construction periods compared to conventional methods.

In addition, the upper end of the steel sheet pile wall 15a, the upper surface of the filling type permeation prevention part 21, and the top end 10a of the embankment 10 are located at approximately the same height, and since these are integrally paved, Water leakage into the upstream slope 10b from the crest of the embankment and into the embankment can be prevented.
Furthermore, since the steel sheet pile wall 15a is installed at the position where the upstream slope 10b and the normal full water level intersect, the amount of water stored in the entire reservoir is not reduced. Furthermore, since the lower end of the steel sheet pile wall 15a is supported by a plurality of steel members 15c installed below the lower end or the permeable steel wall 15b, the steel sheet pile wall 15a can be reliably installed, The groundwater flow in the cut-off wall 10 and the soft layer 30 just below the cut-off wall 10 is not hindered. In order to more firmly support the steel sheet pile wall 15a by the supporting member 18, a connecting member using H-shaped steel or the like is provided over the extending direction of the steel sheet pile wall 15a including the upper part of the supporting member 18. A steel sheet pile (water permeable The steel sheet pile wall 15b or the steel member 15c) and another steel sheet pile 16 may be connected.

Further, when a structure 25 such as a bottom gutter extending in the width direction of the bank body 10 is provided inside the bank body 10, a plurality of steel sheets provided at predetermined intervals in the extending direction of the steel sheet pile wall 15a The steel sheet pile 15c is installed at a position avoiding the structure 25, and is positioned above the structure 25 among the plurality of steel sheet piles 16 constituting the permeable steel wall 15b extending in the extending direction of the steel sheet pile wall 15a. Since the lower end of the steel sheet pile 16 located at 16 does not reach the structure 25, the steel member 15c or the permeable steel wall 15b installed inside the bank 10 interferes with the structure 25, causing the structure Damage to the object 25 can be prevented.

(Second embodiment)
FIG. 7 is a cross-sectional view showing a seepage failure prevention structure for a bank body according to a second embodiment.
The difference between the second embodiment and the above-described first embodiment is the configuration of the protection portion 20 that protects the upstream slope 10b above the full water position 12 or its vicinity, so this point will be described below. In some cases, parts common to those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the present embodiment, the protection part 20 includes a surface type permeation prevention part 24 made of a water impermeable material provided along the upstream slope 10b above the full water position or its vicinity, a steel wall 15a and a surface type It has a structure having a filled-type permeation prevention portion 21 a made of a water-impermeable material filled between the permeation prevention portion 24 and the permeation prevention portion 24 .
Examples of the surface-type permeation prevention part 24 include a concrete block installed on the upstream slope 10b, a shotcrete applied on the upstream slope 10b, and a water-impermeable sheet or geotextile covering the upstream slope 10b. is not limited to this.
Such a surface type permeation prevention part 24 is constructed so as to cover the upstream slope 10b above the full water position 12 after the steel sheet pile wall 15 is driven at the full water position 12 of the upstream slope 10b. It may be constructed before the sheet pile wall 15 is placed. Also, if there is an existing surface protection member such as a concrete block on the upstream slope 10b, only the surface protection member at the portion where the steel sheet pile will be driven may be removed and the existing material may be utilized. Also, the upper end of the surface type permeation prevention portion 24 is located at a position substantially equal to the top end 10a of the bank body 10. As shown in FIG.
Further, the support member 18 that supports the steel sheet pile wall 15a may be the water permeable steel sheet pile wall 15b or a plurality of steel members 15c as in the first embodiment.

In addition, the filling type permeation prevention part 21a is formed by filling impermeable material such as blade metal clay, soil cement or bentonite between the steel wall 15a and the surface type permeation prevention part 24. . Such a filling type permeation prevention portion 21a is formed in a right-angled triangular cross section and is in close contact with the surface of the steel sheet pile wall 15a facing the embankment body 10 side and the surface of the surface type permeation prevention portion 24. As shown in FIG.
Furthermore, the upper end of the steel sheet pile wall 15a, the upper surface of the filling type permeation prevention portion 21a, the upper end of the surface type permeation prevention portion 24, and the top end 10a of the bank body 10 are at substantially the same height position, and the steel sheet pile wall 15a The upper end, the upper surface of the filling type permeation prevention portion 21a, the upper end of the surface type permeation prevention portion 24, and the top end 10a of the bank body 10 are integrally paved to form a paved portion 22. As shown in FIG.

According to the present embodiment, the protection part 20 for protecting the upstream slope 10b above the full water position 12 or its vicinity is provided along the upstream slope 10b above the full water position 12 or its vicinity. Since it has the permeation prevention part 24 and the filling type permeation prevention part 21a filled between the steel wall 15a and the surface type permeation prevention part 24, at the upstream slope 10b which is the starting point of permeation failure, when the water increases Infiltration can be prevented more reliably, and seepage destruction of the embankment body 10 can be suppressed.
In addition, since the surface type permeation prevention part 24 is provided along the upstream slope 10b, the construction cost and construction period can be shortened compared to the conventional construction method of replacing or improving the ground material of the embankment body 10.
Furthermore, it is possible to suppress the surface type penetration prevention part 24 from being peeled off or damaged from the upstream slope 10b, and even if the surface type penetration prevention part 24 is peeled off from the upstream slope 10b, it is dammed by the steel sheet pile wall 15a. Therefore, it can be prevented from falling into the reservoir 11 and being submerged.

10 bank body 10a crest 10b upstream slope 11 reservoir 12 full water position 15a steel sheet pile wall (steel wall)
15b Permeable steel sheet pile wall (permeable steel wall)
15c Steel member 18 Supporting part 20 Protection part 21 Filling type penetration prevention part 21a Filling type penetration prevention part 22 Pavement part 24 Surface type penetration prevention part 25 Structure

Claims (5)

A bank-body seepage failure prevention structure for suppressing seepage failure of a bank body provided on at least a part of the outer periphery of a reservoir,
Assuming that the reservoir side is the upstream side across the bank, a steel wall is provided on the upstream slope of the bank on the upstream side and at or near a full water position at a height equal to the full water level of the reservoir. is installed so as to protrude upward along the extending direction of the bank body,
The lower end of the steel wall is located below the full-water position and is installed below the lower end of the steel wall, and the lower end is embedded in the ground provided directly below the embankment. supported by a member,
A protection part is provided to protect the upstream slope above the full water position or its vicinity,
A seepage failure prevention structure for a bank body, wherein the protection part is a filling-type seepage prevention part made of a water-impermeable material filled between the steel wall and the upstream slope. A bank-body seepage failure prevention structure for suppressing seepage failure of a bank body provided on at least a part of the outer periphery of a reservoir,
Assuming that the reservoir side is the upstream side across the bank, a steel wall is provided on the upstream slope of the bank on the upstream side and at or near a full water position at a height equal to the full water level of the reservoir. is installed so as to protrude upward along the extending direction of the bank body,
The lower end of the steel wall is located below the full-water position and is installed below the lower end of the steel wall, and the lower end is embedded in the ground provided directly below the embankment. supported by a member,
A protection part is provided to protect the upstream slope above the full water position or its vicinity,
The protection part includes a surface type permeation prevention part made of a water impermeable material provided along the upstream slope above the full water position or its vicinity, and a surface type permeation prevention part made of the steel wall and the surface type permeation prevention part. A seepage failure prevention structure for a bank body, comprising: a filling type seepage prevention portion made of a water-impermeable material filled between them. 3. A seepage failure prevention structure for a bank according to claim 1 or 2, wherein the upper end of said steel wall, the upper surface of said protective portion and the top of said bank are integrally paved. The supporting member is a plurality of steel members provided at predetermined intervals in the extending direction of the steel wall, or a permeable steel wall extending in the extending direction of the steel wall. The seepage failure prevention structure for a bank body according to any one of claims 1 to 3. A structure extending in the width direction of the bank is provided inside the bank,
When the support member is a plurality of steel members provided at predetermined intervals in the extending direction of the steel wall , the steel member is installed at a position avoiding the structure,
When the support member is a permeable steel wall extending in the direction in which the steel wall extends, one of the plurality of steel sheet piles constituting the permeable steel wall is located above the structure. The reinforcement structure for a bank body according to claim 4, wherein the lower end of the steel sheet pile does not reach the structure.

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