JP7824619B2 - Reinforcement structure of existing embankments - Google Patents

Description

The present invention relates to a reinforcement structure for existing embankments.

River levees and the banks of reservoirs and reservoirs used for water storage are primarily constructed using soil-based materials and are therefore "earth structures" whose purpose is to stop water (water impermeability). The following explanation will use river levees as an example.

A levee 301 of a river 303, as shown in Figure 15, is known. The levee 301 has a planned high water level set as the maximum water level (maximum under normal conditions) flowing through the river 303. However, if an emergency occurs due to heavy rain such as a typhoon caused by climate change, and the amount of water flowing through the river 303 increases to a level that causes the levee 301 to overflow, flooding occurs due to the overflow (see arrows A11 to A13). When the water in the river 303 overflows, the overflowing water scours the back slope 311 of the levee 301, causing the back slope 311 to collapse and the portion of the levee 301 on the back side of the river to collapse. Note that the reference numeral 305 in Figure 15 denotes a house.

Furthermore, when an emergency occurs and the amount of water flowing through river 303 increases, water seeps into levee 301, causing seepage failure of levee 301 and resulting in flooding (see arrows A14 to A17), or scouring caused by the flow of water flowing through ground 307 causes scouring failure of levee 301 and resulting in flooding (see arrows A18 to A23). In other words, the flow of water causes erosion and scouring of levee 301, leading to its collapse. Furthermore, when the water level within levee 301 rises, water from river 303 seeps into levee 301, causing a piping phenomenon (see dashed line 313 in Figure 16), weakening the strength of levee 301 and resulting in its collapse through seepage.

Furthermore, if an emergency occurs and the amount of water flowing through river 303 increases, the water flow (see arrow A24) will erode the surface of the levee, causing levee 301 to collapse and flooding. That is, the dashed line 309 shown in Figure 15 will gradually move from the left side to the right side of Figure 15, causing levee 301 to collapse and flooding to occur. Note that the direction of water flow in river 303 is perpendicular to the plane of the paper in Figure 15, so arrow A24 is shown as a circle rather than an arrow.

By the way, with the increasing intensity of rainfall, which is thought to be partly due to climate change, it is thought that the current approach of containing floods caused by rainfall within the river channel (so-called levees 301) is not the best solution, and so there is an idea called river basin flood control, which involves allowing water to overflow in a planned manner.

The concept of river basin flood control is as follows:

Improve flood retention and storage functions by developing flood control basins, constructing and utilizing levee dikes, and strengthening the flood control functions of dams. Improve land use and living arrangements by restricting land use, relocating houses, and raising housing levels.

In river basin flood control, policies such as relocating target areas or deliberately allowing water to overflow can pose significant problems, including residents' feelings about relocation, costs, and the duration of the project. Furthermore, deliberate overflowing is likely to require significant costs and construction time for subsequent recovery and reconstruction.

It is also possible to upgrade the conventional levee 301 to a high-standard levee.

High-standard levees are made wider so that even if they overflow, water flows gently over the levee, preventing them from collapsing. High-standard levees are also made wider so that even if water seeps in, they are more likely to prevent erosion inside the levee, leading to collapse. High-standard levees also have a core structure (made of concrete, steel, or clay) that prevents the levee from collapsing in the event of overflow and maintains its shape.

Here, Patent Document 1 is cited as a document related to conventional technology.

Japanese Patent Application Laid-Open No. 2017-206863

However, installing a high-standard levee would require rebuilding or extensive modification of the levee, which would extend the construction period and increase costs.

The present invention aims to provide a reinforcement structure for existing levees (embankments) and reservoir embankments and banks, which can reduce costs and shorten construction periods by utilizing existing levees (embankments) and reservoir embankments and banks almost as they are, and which can protect the levees, reservoir embankments and banks from erosion, scouring, seepage, overflowing and destruction due to earthquakes, thereby preventing flooding, even when the flow rate exceeds the planned high water level.

The invention described in claim 1 is a reinforcement structure for an existing levee, comprising: a key installed along the levee, with its upper portion exposed and its lower portion recessed into the levee; a plurality of support piles installed at predetermined intervals along the levee, with its upper and middle portions exposed and its lower portion recessed into the ground below the levee outside the levee; a deck slab installed between the key and the support piles in the width direction of the levee, extending long along the levee in the longitudinal direction of the levee and installed between the key and the support piles in the up-down direction at the upper portion of the key and the upper portion of the support pile; and a partition wall installed between the support piles along the levee and closing the space between the support piles.

The invention described in claim 2 is a reinforcement structure for an existing levee, comprising: a support body installed along the levee, with its upper portion exposed, its middle portion recessed into the levee, and its lower portion recessed into the ground below the levee; a plurality of support piles installed at predetermined intervals along the levee, with its upper and middle portions exposed and its lower portion recessed into the ground outside the levee; a deck slab installed between the support body and the support piles in the width direction of the levee, extending long along the length of the levee in the longitudinal direction of the levee and installed between the support body and the support piles in the up-down direction at the upper portion of the support body and the upper portion of the support pile; and a partition wall installed between the plurality of support piles along the levee, closing the space between the plurality of support piles.

The invention described in claim 3 is a reinforcement structure for an existing embankment, comprising: a support body that is continuously arranged in the longitudinal direction of the embankment, with an upper portion exposed, an intermediate portion recessed into the embankment, and a lower portion recessed into the ground below the embankment; a plurality of support piles that are installed at predetermined intervals along the embankment, with their upper and intermediate portions exposed and their lower portions recessed into the ground outside the embankment; and a deck slab that is installed between the support body and the support piles in the width direction of the embankment, extends long along the longitudinal direction of the embankment, and is installed between the support body and the support piles in the up-down direction at the upper portion of the support body and the upper portion of the support pile, and extends horizontally or in a direction approximately horizontal.

This invention has the advantage of being able to reduce costs and shorten construction times by utilizing existing levees (embankments) and the banks and banks of reservoirs and reservoirs almost as they are, while also providing a reinforcement structure for existing levees, banks and banks of reservoirs and reservoirs that protects them from erosion, scouring, seepage, overflowing, and destruction due to earthquakes, thereby preventing the occurrence of floods, even when the flow rate exceeds the planned high water level.

1 is a plan view of a reinforcement structure for an existing embankment according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 2 is a cross-sectional view taken along the line III-III in FIG. 1. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. FIG. 5 is an enlarged view of a V portion in FIG. 4. FIG. 4 is an enlarged view of a portion VI in FIG. 3 . FIG. 7 is an enlarged view of a portion VII in FIG. 3 . 2. (a) is an enlarged view of a portion VIIIA in FIG. 2, and (b) is an enlarged view of a portion VIIIB in FIG. FIG. 4 is a diagram corresponding to FIG. 2 and FIG. 3, showing an example of changing the positions of the support piles and partition walls of an existing levee according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of a reinforcement structure for an existing embankment according to a second embodiment of the present invention, corresponding to FIG. 2 . FIG. 10 is a cross-sectional view of a reinforcement structure for an existing embankment according to a third embodiment of the present invention, corresponding to FIG. 2 . FIG. 10 is a cross-sectional view of a reinforcement structure for an existing embankment according to a fourth embodiment of the present invention, corresponding to FIG. 2 . FIG. 10 is a cross-sectional view of a reinforcement structure for an existing embankment according to a fifth embodiment of the present invention, corresponding to FIG. 2 . FIG. 10 is a cross-sectional view of a reinforcement structure for an existing embankment according to a sixth embodiment of the present invention, corresponding to FIG. 2 . FIG. 1 is a cross-sectional view of a conventional embankment.

First Embodiment
The reinforcement structure 1 for an existing levee according to the first embodiment of the present invention is intended to reinforce, for example, an levee (existing levee; an levee of an existing constructed structure) 5, which is a flood control structure for a river 3, and is configured to include a first support pile 7, a second support pile 9, a deck (artificial deck) 11, and a partition wall 13, as shown in Figures 1 to 4.

For the sake of explanation, a specific direction perpendicular to the up-down direction (vertical direction; height direction) is referred to as the width direction, and a specific direction perpendicular to both the up-down and width directions is referred to as the upstream-downstream direction. Water 14 of the river 3 is assumed to flow from the upstream side to the downstream side within the width direction.

Note that Figures 1 to 4 only show one levee (levee body), but there may be another similar levee on the opposite side of the river 3, and the existing levee reinforcement structure 1 may also be applied to this opposite levee. Furthermore, the levee 5 and the existing levee reinforcement structure 1 that reinforces it do not necessarily extend in a straight line in the upstream and downstream directions, but may extend in a curved or bent manner.

The first support pile 7 is formed in the shape of a long, thin rod. The longitudinal direction of the first support pile 7 is generally in the vertical direction. In the width direction of the embankment 5, the first support pile 7 is located at the top end 6 of the embankment 5 (the peak of the embankment 5).

The upper portion of the first support pile 7 is exposed from the embankment 5. Furthermore, the middle portion of the first support pile 7 is driven into the embankment 5, and the lower portion is driven into the ground 15 below the embankment 5, so it penetrates both the embankment 5 and the ground 15.

A plurality of first support piles 7 are provided. The first support piles 7 are installed along the embankment 5 at predetermined intervals in the longitudinal direction of the embankment 5 (upstream and downstream directions) between the embankment 5 and the ground 15.

Like the first support pile 7, the second support pile 9 is also formed in the shape of a long, thin rod. The longitudinal direction of the second support pile 9 is also roughly vertical.

In order to minimize the increase in the width dimension (dimensions of the embankment floor) of the embankment 5 due to the installation of the existing embankment reinforcement structure 1 and to provide a deck slab 11 above the back slope of the embankment 5, the second support pile 9 is located in the width direction of the embankment 5 at the back slope toe (lower part of the embankment slope) 19 of the back slope (the landward embankment slope as viewed from above the embankment 5) 17 of the embankment 5, or near the back slope toe 19 of the back slope 17 of the embankment 5, as shown in Figure 2, etc.

The second support pile 9 may be located at the rear slope 17 of the embankment 5 in the width direction of the embankment 5, or may be located a predetermined distance outside the embankment 5 from the rear slope toe 19 of the rear slope 17 of the embankment 5 (for example, at the side belt 21). Note that the side belt 21 may be in a so-called zero-meter zone (land where the ground surface elevation is below mean sea level at high tide).

The second support piles 9 are, for example, exposed at their upper and middle sections and driven into the ground 15 at their lower sections outside the levee 5, so that they are embedded in the ground 15. Like the first support piles 7, multiple second support piles 9 are provided. The multiple second support piles 9 are installed in the ground 15 at predetermined intervals along the levee 5 in the longitudinal direction of the levee 5 (upstream and downstream directions).

The deck 11 is located between the first support pile 7 and the second support pile 9 in the width direction of the embankment 5. In other words, the deck 11 extends from at least the first support pile 7 to the second support pile 9 in the width direction of the embankment 5.

The deck slab 11 extends longitudinally along the embankment 5. Furthermore, in the vertical direction, the deck slab 11 is installed integrally with the first support pile 7 and the second support pile 9 at the upper portion (e.g., the upper end surface) of the first support pile 7 and the upper portion (e.g., the upper end surface) of the second support pile 9 on the upper side of the embankment 5.

The thickness direction of the deck slab 11 is roughly vertical, and the deck slab 11 extends horizontally or in a direction close to horizontal. A portion of the underside of the deck slab 11 (the inner portion in the width direction) is attached to the top edge 6 of the embankment 5 via a hood (not shown), or is in direct contact with the top edge 6 of the embankment 5. In addition, a mooring bollard (not shown) is installed on the top surface of the deck slab 11 on the top face 55 side.

Partition walls 13 are installed between the first support piles 7 along the embankment 5 (in the longitudinal direction of the embankment 5), and are also installed between the second support piles 9 along the embankment 5. The partition walls 13 close off the spaces between the first support piles 7, and also close off the spaces between the second support piles 9.

In addition, partition walls 13 may be installed along the embankment 5 between at least one of the first support piles 7 and the second support piles 9, closing off at least one of the spaces between the first support piles 7 and the second support piles 9.

The thickness direction of the partition wall 13 is roughly the same as the width direction. The partition wall 13 extends roughly in the vertical direction along the multiple support piles 7, 9, and also in the longitudinal direction of the embankment 5.

The provision of the partition walls 13 forms a water cut-off wall for water 14 flowing inside the body of the embankment 5. In other words, the provision of the partition walls 13 between the multiple first support piles 7 forms a water cut-off wall (hybrid vertical water cut-off wall) 23 for water flowing inside the body of the embankment 5, together with the first support piles 7 and the partition walls 13. Furthermore, the provision of the partition walls 13 between the multiple second support piles 9 forms a water cut-off wall (hybrid vertical water cut-off wall) 25 for water flowing inside the body of the embankment 5, together with the second support piles 9 and the partition walls 13.

In addition, when partition walls 13 are provided both between the first support piles 7 and between the second support piles 9, a fail-safe structure (fault-tolerant system) with double water-stopping walls is formed.

In the areas where the first support pile 7, embankment 5, and second support pile 9 are installed, the ground 15 consists of hard ground (e.g., an impermeable layer) 27 and soft ground (e.g., a permeable layer) 29 above the hard ground.

The upper part of the lower portion of the first support pile 7 penetrates the soft ground 29, and the lower part of the lower portion of the first support pile 7 penetrates into the hard ground 27. The upper part of the lower portion of the second support pile 9 also penetrates into the soft ground 29, and the lower part of the lower portion of the second support pile 9 also penetrates into the hard ground 27.

The existing embankment reinforcement structure 1 also has a parapet 31. The parapet 31 protrudes a predetermined height above the top surface of the deck slab 11 and extends continuously along the embankment 5 (in the longitudinal direction of the embankment). The parapet 31 is also located at the outer end of the deck slab 11 in the width direction (the side opposite the river 3). Furthermore, as shown in Figure 7, the parapet 31 is configured so that the protruding height from the deck slab 11 can be changed.

Here, we will explain the embankment 5 and the existing embankment reinforcement structure 1 in more detail.

The levee 5 is composed of a levee body 33 and rubble 35 covering the levee body 33. The cross section of the levee 5 (a cross section taken along a plane perpendicular to the upstream and downstream directions) is formed, for example, in the shape of an isosceles trapezoid.

The first support pile 7 and the second support pile 9 are made, for example, of steel pipes and have the same shape. The upper end surface of the first support pile 7 is exposed from the embankment 5 at the top 6 of the embankment 5. In the vertical direction, the positions of the upper end surface of the first support pile 7 and the top 6 of the embankment 5 are approximately aligned. In the vertical direction, the positions of the first support pile 7 and the second support pile 9 are approximately aligned.

As shown in Figure 5(a), the partition wall 13 is made of steel material such as sheet piles, and extends between adjacent first support piles 7 (second support piles 9) in the upstream and downstream directions. Furthermore, the partition wall 13 extends from the deck slab 11 to the interior of the ground 15 in the vertical direction. As shown in Figure 5(b), the partition wall 13 may also be made of steel pipes similar to the support piles 7 and 9.

As shown in Figure 6(a), the lower end of the partition wall 13 is located on the upper surface of the hard ground 27. As shown in Figure 6(b), the lower end of the partition wall 13 may be located within the hard ground 27, or as shown in Figure 6(c), the lower end of the partition wall 13 may be located above the upper surface of the hard ground 27 and in soft ground 29.

The deck slab 11 is constructed from, for example, steel materials such as sheet piles or deck plates, precast concrete slabs, or cast-in-place concrete slabs instead of precast concrete slabs, and the underside of the deck slab 11 is joined to the upper end surfaces of the first support piles 7 and the second support piles 9.

Here, we will explain, with reference to Figure 7, the configuration that allows the protruding height of the parapet 31 from the deck slab 11 to be changed.

In the configuration shown in Figure 7(c), the parapet 31 is composed of a parapet main body 37 and a parapet raising body 39. The parapet raising body 39 is attached to the parapet main body 37 via a hinge portion 41 and is capable of rotating relative to the parapet main body 37.

When the water level is below the level at which the water would overflow the levee, the parapet raising body 39 covers the parapet main body 37, as shown by the solid line. On the other hand, when the water level is likely to exceed the level at which the water would overflow the levee, the parapet raising body 39 rotates, for example, 180 degrees relative to the parapet main body 37, as shown by the two-dot chain line, to raise the height of the parapet 31.

Note that there is a small amount of water leakage at the hinge portion 41, which is tolerable, but to prevent this leakage, a sealant or packing may be provided at the hinge portion 41.

In the configuration shown in Figure 7(a), the second support pile 9 (first support pile 7) is composed of an upper member 43 and a lower member 45. The upper member 43 can be freely moved and positioned in the vertical direction relative to the lower member 45. The parapet 31 can be raised by moving the upper member 43 upward from the state shown in Figure 7(a) to the state shown in Figure 7(b).

Although not shown in Figures 7(a) and 7(b), the partition wall 13 is also composed of an upper member and a lower member, just like the support piles 7 and 9. The upper member of the partition wall 13 is installed integrally with the upper member 43 of the support piles 7 and 9, and the lower member of the partition wall 13 is installed integrally with the lower member 45 of the support piles 7 and 9. As shown in Figures 7(a) and 7(b), even if the height position of the parapet 31 is changed, the upper member of the partition wall 13 and the lower member of the partition wall 13 form a sliding pair with each other, so that the hybrid vertical water cut-off walls 23 and 25 can almost completely stop water flow.

Next, we will explain the flow of water 14 from the river 3 on the levee 5 reinforced by the existing levee reinforcement structure 1.

Under normal circumstances, as shown in Figure 2, water 14 flows through river 3 at a level below the planned high water level. On the other hand, when river 3 rises due to heavy rain or other reasons, water 14 flows through river 3 at a level above the planned high water level. However, even if river 3 rises, if the water level is below the level that would cause the levee to overflow, the parapet 31 prevents overflow (see arrow A1). The planned high water level is the water level that serves as the reference for levee construction, and the height of levee 5 is determined by adding a freeboard to the planned high water level.

Even if the river 3 floods, the hybrid vertical water cut-off wall 23 blocks water that has seeped into the levee 5 and water that flows through the ground 15 (soft ground 29) (see arrows A2, A3, and A4). Furthermore, even if the water flow caused by the flooding of the river 3 (see arrow A5) scours parts of the inside of the levee 5 (see dashed line 30 in Figure 2), this scouring stops at the hybrid vertical water cut-off wall 23.

The reinforcement structure 1 for the existing embankment is composed of a plurality of first support piles 7, whose middle sections penetrate into the embankment 5 and whose lower sections penetrate into the ground 15 below the embankment 5, and which are installed at predetermined intervals along the embankment 5, and a plurality of second support piles 9, whose lower sections penetrate into the ground 15 outside the embankment 5, and which are installed at predetermined intervals along the embankment 5.

The existing embankment reinforcement structure 1 also includes a deck 11. The deck 11 is located between the first support pile 7 and the second support pile 9 in the width direction of the embankment 5, extends longitudinally along the embankment 5, and is installed on the first support pile 7 and the second support pile 9 at the upper portions of the first support pile 7 and the second support pile 9 in the vertical direction, and extends horizontally or in a direction close to horizontal.

Furthermore, the existing levee reinforcement structure 1 is provided with partition walls 13 installed between the first support piles 7 and the second support piles 9 along the levee 5, enclosing the spaces between the multiple support piles 7 and 9.

Because the existing levee reinforcement structure 1 is configured in this way, the existing levee (levee body) 5 can be used almost as is, reducing costs and shortening the construction period. In other words, by installing the first support piles 7, for example, by driving them into the levee 5, the existing levee 5 can be used almost as is without requiring any major modifications.

Furthermore, because the existing levee reinforcement structure 1 is configured as described above, the levee 5 can be protected from erosion, scouring, seepage, overflow, and destruction due to earthquakes, even if the water volume increases. In other words, because the deck 11, support piles 7, 9, and partition wall 13 are provided, erosion, scouring, and seepage caused by increased water can be suppressed by the support piles 7, 9 and partition wall 13, and the deck 11, etc. can prevent destruction of the levee 5 due to overflow.

Furthermore, according to the existing levee reinforcement structure 1, the deck 11 is installed between the first support pile 7 and the second support pile 9, and the second support pile 9 is installed at the toe 19 of the back slope 17 of the levee 5. Therefore, even when the levee 5 is reinforced, the levee 5 is prevented from expanding in the width direction on the opposite side of the river 3. In other words, it is possible to minimize the increase in the width dimension (dimension of the levee base) of the levee 5.

Furthermore, according to the existing embankment reinforcement structure 1, the deck 11 is installed on the first support pile 7 and the second support pile 9, at the upper end surfaces of the first support pile 7 and the second support pile 9. Furthermore, since the thickness direction of the deck 11 is vertical, the deck 11 is positioned slightly above the top edge 6 of the embankment 5 in the vertical direction, and the top surface of the deck 11 extends the top edge 6 of the embankment 5 outward in the width direction. This allows the deck 11 to be used as a promenade or the like that is wider than the top edge 6 of the embankment 5.

In addition, with the existing levee reinforcement structure 1, a portion of the underside of the deck slab 11 is joined to the top 6, making it difficult for water to flow between the top 6 of the levee 5 and the deck slab 11, preventing the levee 5 from collapsing and allowing the length dimensions of the support piles 7 and 9 to be reduced.

In addition, the existing levee reinforcement structure 1 has a parapet 31 that protrudes a predetermined height above the top surface of the deck slab 11 and extends continuously along the levee 5, providing a measure against overflow. In other words, the levee is raised to prevent overflow, and the width of the river 3 is widened to prevent overflow, improving the river's ability to flow down floodwaters.

Furthermore, with the existing levee reinforcement structure 1, the parapet 31 is located on the outside of the deck slab 11 in the width direction, which increases the area of the deck slab 11 through which water flows in plan view. This allows the parapet 31 to hold back water even if the flow rate of the river 3 increases, further preventing overflow.

Furthermore, with the existing levee reinforcement structure 1, the parapet 31 is configured so that the protruding height can be adjusted, making it possible to take measures against overflow according to the water volume. In other words, with the existing levee reinforcement structure 1, the existing levee 5 can be utilized to implement overflow prevention measures, add erosion, scouring, and seepage prevention works, and further improve the levee into a strong levee that is resistant to earthquakes.

Furthermore, the deck slab 11, which is constructed above the levee 5, has an area that is overwhelmingly larger than the top 6 of the levee 5. This allows it to be used not only for its traditional functions (for example, as a footpath or roadway), but also as a storage yard for sandbags and disaster prevention equipment, as a first aid yard in the event of an emergency, and after an emergency situation occurs, as a collection and sorting yard for large amounts of disaster debris, as a temporary storage yard, and as a recovery and reconstruction yard.

Next, referring to Figure 9, we will explain how to change the installation positions of the support piles 7, 9 and the partition wall 13 in the width direction.

In the reinforcement structure 1 for the existing levee shown in Figures 1 to 4, etc., the first support pile 7 and partition wall 13 (hybrid vertical water cut-off wall 23) are placed where indicated by the two-dot chain line 47 in Figure 9, and the second support pile 9 and partition wall 13 (hybrid vertical water cut-off wall 25) are placed where indicated by the two-dot chain line 49 in Figure 9.

However, the positions of the hybrid vertical water blocking walls 23 and 25 in the width direction are not limited to those shown in Figures 1 to 4, etc.

That is, the hybrid vertical water cut-off wall 23 may be placed where indicated by the two-dot chain line 51 (at or near the toe 57 (lower part of the embankment slope) of the front slope (the slope of the embankment facing the river when viewed from above the embankment 5) 55 of the embankment 5), or at any position between the two-dot chain line 47 and the two-dot chain line 51. The area connecting the toe 57 of the front slope and the toe 17 of the back slope (the area on the top surface of the ground 15) is called the embankment base.

The hybrid vertical water cutoff wall 25 may also be placed where indicated by the two-dot chain line 53 (at the top 6 of the levee 5), or at any position between the two-dot chain line 49 and the two-dot chain line 53.

In a configuration in which the hybrid vertical water cutoff wall 23 is positioned at the two-dot chain line 51, the deck slab 11 also extends inward in the width direction. In this case, fenders 59 are installed at the inner edges of the hybrid vertical water cutoff wall 23 and the deck slab 11. Details of the fenders 59 will be described later.

Here, we will further explain the reinforcement structure 1 for existing levees. This explanation may overlap with the above description. Furthermore, existing levees 5 include embankments (existing embankments) and banks (existing banks) of reservoirs and ponds.

The support piles 7 and 9 are erected (driven) down to a layer (hard ground) 27 that can support all loads acting on the deck slab 11 (deck slab 11, rising water level, heavy work equipment, seismic force, etc.).

The partition wall (vertical water cut-off wall) 13 connected to the support piles 7 and 9 is erected to an arbitrary depth corresponding to the factors that may cause the levee to collapse (erosion, scouring, seepage, overflow, earthquake), as shown in Figure 6, etc.

To prevent a small gap from forming between the deck slab 11 and the top 6 of the embankment 5 and becoming a waterway, it is desirable to install the above-mentioned buffer hood between the top 6 of the embankment 5 and the deck slab 11, rather than installing the deck slab 11 directly on the top 6 of the embankment 5. Layers of asphalt mat, asphalt mastic, concrete, etc. should be used as buffer hoods. The buffer hoods may also be constructed before the deck slab 11 is constructed.

For construction purposes, the support piles 7, 9 and partition wall 13 (vertical water-stopping walls 23, 25) are preferably made of steel (steel pipe piles, steel sheet piles), but they may also be made of concrete or other materials.

For example, steel sheet piles, steel pipe sheet piles, combined steel sheet piles, box sheet piles, H-shaped steel sheet piles, steel plates, cast-in-place concrete sheet piles, etc. may be used for the steel vertical water cut-off walls 23, 25. Steel piles, concrete piles, cast-in-place piles, etc. may also be used for the support piles 7, 9.

Let's say that, based on increased rainfall due to climate change (for example, the 2016 Paris Agreement), it is assumed that the average global temperature will rise by 2°C. Based on this assumption, rainfall will increase by 1.1 times and the frequency of floods will double. In this case, in addition to conventional hard measures such as strengthening levees as flood prevention measures, it has been reported that efforts will be made to strengthen soft measures, such as reviewing technical standards and raising levees.

In the first place, no matter how much precipitation increases, flooding will not occur unless levee 5 breaks (collapses) or water overflows from levee 5. On the other hand, there will also be damage caused by water overflowing (overflowing) from areas without levee 5.

Here, we will explain the damage to Levee 5, its main causes, and the consequences.

If the main cause of damage is an unexpected earthquake, the result will be that levee 5 will collapse and become unsound. Flooding will occur even if the planned high water level and planned high water flow rate have not been reached.

If the main cause of damage is ground liquefaction due to an earthquake, the result will be the collapse of levee 5, leaving it in an unsound state. Flooding will then occur even if the planned high water level and planned high water flow rate have not been reached.

If the main cause of damage is consolidation settlement of the levee 5, the resulting height of the top 6 of the levee 5 will be insufficient, leaving it in an unsound state. Flooding will then occur even below the flood danger level or the planned high water level.

If the main cause of damage is overflow due to unexpected rainfall, levee 5 will not collapse and will remain intact, but water will overflow levee 5, causing a flood.

If the main cause of damage is the erosion of levee 5 by water, the scouring of levee 5 by water, or the infiltration of water into levee 5, the result will be the collapse of levee 5 and its unsound state. Flooding will then occur even if the planned high water level or planned high water flow rate has not been reached.

However, with levee 5, which employs existing levee reinforcement structure 1, the damage to levee 5 described above can be prevented. In other words, it is possible to provide a healthy levee that has resolved all of the main causes of the damage to levee 5 described above.

Existing levee reinforcement structure 1 utilizes the current levee 5, even if it is in a sound state, regardless of whether it is in an unsound state. Furthermore, existing levee reinforcement structure 1 utilizes the administrative grounds in front of and behind the current levee 5. In other words, the adoption of existing levee reinforcement structure 1 does not unnecessarily increase (spread) the width dimension of levee 5 (dimensions of the levee base).

In the reinforcement structure 1 of the existing levee, the height of the top 6 of the levee 5 (more precisely, the height of the top of the reinforcement structure 1 of the existing levee, which corresponds to the height of the top 6) is raised by a parapet 31 in order to improve the flow capacity of water 14 in response to abnormal high water levels caused by climate change.

In addition, the existing levee reinforcement structure 1 is equipped with a deck 11 and parapet 31 to improve the flow capacity of water 14 in response to abnormal high water flow rates caused by climate change.

Even if current levee 5 collapses due to factors that could cause its collapse (unforeseen earthquake, liquefaction during an earthquake, consolidation settlement, overflow, erosion, scouring, seepage), if reinforcement structure 1 for the existing levee has been constructed, it will be protected from the risk of flooding by resisting the external forces that could cause levee 5 to collapse.

The joints (connections; see Figure 8) between the deck slab 11 and the support piles 7, 9, which transmit the loads transmitted from the superimposed load and external forces to the bearing layer (hard ground) 27, and the deck slab 11, as well as the joints (connections; see Figure 8) between the deck slab 11 and the vertical cut-off walls 23, 25, which resist the main factors that cause damage to the embankment 5, are generally referred to as supports (bearings). The main role of the supports is to transmit the load of the upper structure (deck slab 11) to the lower structure (support piles 7, 9).

In addition, in the existing embankment reinforcement structure 1, the heads (upper ends) of the hybrid vertical water cut-off walls 23, 25 are embedded in the deck slab 11 for the purpose of water blocking, as shown in Figures 8(a) and 8(b), for example. In other words, the interface between the hybrid vertical water cut-off walls 23, 25 and the interface of the deck slab 11 where the hybrid vertical water cut-off walls 23, 25 are embedded is embedded for the length required for water blocking.

In the configuration shown in Figure 8, the upper ends of the hybrid vertical water cutoff walls 23, 25 are embedded in grooves formed in the underside of the deck slab 11, as shown in Figure 8, but a configuration in which no grooves are provided on the underside of the deck slab 11 and the upper ends of the hybrid vertical water cutoff walls 23, 25 are joined to the underside of the deck slab 11 may also be used.

In addition, measures may be taken to prevent water leaks from occurring at the interface between the hybrid vertical water-stopping walls 23, 25 (embedded areas) and the deck slab 11 by using water-stopping inclusions (not shown) such as rubber gaskets.

Furthermore, if water-stopping works (for example, the application of a swelling water-stopping material, etc.) are applied to the vertical joints (joints extending in the vertical direction) between the components (for example, steel plates, sheet piles) that make up the hybrid vertical water-stopping walls 23, 25 and to the vertical joints with the support piles, the structure will be more stable.

In addition, although the top surface of the deck 11 is horizontal, the top surface (surface) of the deck 11 may be sloped. For example, the top surface of the deck 11 may be sloped toward the river 3 to allow for drainage. In other words, the top surface of the deck 11 may be sloped in the width direction so that it is lower on the river 3 side and higher on the opposite side of the river 3.

The height (protruding height) of the parapet 31's top from the deck slab 11 does not need to be constant. If there is a reservoir or wasteland on the land side (outside the levee 5; opposite the river 3) where flooding will not cause any problems, the top position of the parapet 31 in the vertical direction (the height dimension value of the parapet 31) may be changed appropriately along the length of the levee 5 to facilitate drainage to the area (reservoir, etc.), reduce the amount of flow toward the river mouth, and prevent or mitigate flood disasters. That is, the parapet 31 may be partially cut down, shaped like a comb, or have holes drilled into it. In other words, a cross-sectional defect may be pre-constructed in the parapet 31.

The partition wall 13 may also be used as a support pile. In this case, the support piles that make up the hybrid vertical water cut-off walls 23, 25 are not necessary.

All hybrid vertical water cutoff walls 23, 25 (support piles 7, 9 and partition wall 13) extend vertically, but they may be angled to provide the most effective (efficient) reaction force against external forces (inclined piles). However, not all piles need to be inclined piles (piles extending at an angle); they may be composite piles combined with vertical piles. Furthermore, the inclination direction of the inclined piles may be changed as appropriate for each support pile.

Materials that can be used for the hybrid vertical water cut-off walls 23, 25 (support piles 7, 9 and partition wall 13) are typically piles and sheet piles, but they can also be precast (prefabricated in a factory) and cast-in-place (concrete installed on-site) materials such as steel piles and underground continuous walls.

The existing levee reinforcement structure 1 is an applied reinforcement structure when the top 6 of the existing levee 5 is in constant use (for sidewalks, roadways, etc.), and the existing levee reinforcement structure 1 can be used for both weak and strong levee 5.

The hybrid vertical water cut-off walls 23, 25 may be installed either inside or outside the levee 5, but if they are installed on the river 3 side, the top 6 of the levee 5 can be utilized as usual.

A ladder may be installed in addition to the fender 59 shown in Figure 9. The fender 59 and ladder are berthing equipment for ships used in rescue and relief operations. Installing the fender 59 and ladder can play an important role in disaster prevention preparation, recovery, and reconstruction. Furthermore, installing a mooring bollard (not shown) on the top inside of the deck slab 11 (on the side of the top deck 55) will make ship docking more effective.

Second Embodiment
The reinforcement structure 1a for an existing embankment according to the second embodiment shown in Figure 10 differs from the reinforcement structure 1 for an existing embankment according to the first embodiment of the present invention in that the deck slab 11 is spaced upward from the embankment 5, but in other respects it is configured in the same way as the reinforcement structure 1 for an existing embankment, and can be modified in the same way as the reinforcement structure 1 for an existing embankment.

In the existing embankment reinforcement structure 1a, the thickness direction of the deck slab 11 is roughly vertical, and the deck slab 11 is separated from the embankment 5 above it. In addition, the support piles 7, 9 and the partition wall 13 are also extended upward.

According to the existing levee reinforcement structure 1a, the deck 11 is located above the levee 5 and away from the levee 5, so the hybrid vertical water cut-off walls 23, 25 protrude above the levee 5. Even if the flow rate of water 14 in the river 3 increases, the hybrid vertical water cut-off walls 23, 25 can hold back the water 14, further preventing overflow. Furthermore, the top 6 of the levee 5 and the upper surface of the deck slab 11 can be effectively used as paths for pedestrians and vehicles.

Third Embodiment
The reinforcing structure 1b for an existing levee according to the third embodiment shown in Figure 11 is adopted for a strong levee 5. The reinforcing structure 1b for an existing levee according to the first embodiment of the present invention differs from the reinforcing structure 1 for an existing levee according to the first embodiment of the present invention in that a water-stop key (key) 61 is used instead of the first support pile 7, but in other respects it is configured in the same way as the reinforcing structure 1 for an existing levee, and it is possible to make almost the same modifications as those to the reinforcing structure 1 for an existing levee.

The reinforcing structure 1b for an existing embankment according to the third embodiment is composed of a key 61, support piles (second support piles) 9, a deck slab 11, and a parapet 31.

The upper part of the key 61 is exposed from the levee 5, and the lower part is recessed into the levee 5 (only the upper part of the levee 5). The key 61 is also installed along the levee 5 (in the longitudinal direction of the levee). The key 61 is installed in place of the first support pile 7 when the levee 5 has sufficient strength to withstand unexpected river water volumes and there is no risk of collapse. The key 61 is installed at the top center of the levee 5 and has an inverted isosceles trapezoidal shape.

Multiple support piles 9 are installed. The upper and middle sections of the support piles 9 are exposed, while the lower sections are driven into the ground 15 outside the embankment 5, thereby embedding the piles. The multiple support piles 9 are installed in the ground 15 at predetermined intervals along the length of the embankment 5.

The deck 11 is located between the key 61 and the support pile 9 in the width direction of the embankment 5, extends longitudinally along the embankment 5, and is installed integrally with the key 61 and the support pile 9 at the upper part (e.g., the upper end surface) of the key 61 and the upper part (e.g., the upper end surface) of the support pile 9 above the embankment 5. The deck 11 extends horizontally or in a direction close to horizontal, and the thickness direction of the deck 11 is generally vertical.

In addition, the existing levee reinforcement structure 1b is provided with partition walls 13. The partition walls 13 are installed between multiple support piles 9 along the levee 5 (in the longitudinal direction of the levee), enclosing the spaces between the multiple support piles 9. The thickness direction of the partition walls 13 is roughly the same as the width direction. Note that the partition walls 13 may be omitted.

In the existing levee reinforcement structure 1b, the keys 61 penetrate only into the levee 5 and are installed along the levee 5, making installation of the keys 61 easier than when using the first support piles 7. In other words, using keys 61 (made of concrete, for example) instead of the hybrid vertical water cut-off wall 23 makes construction easier.

In addition, the key 61 may be a shear key that has shear resistance to suppress horizontal movement of the deck slab 11.

If levee 5 is strong enough to withstand all of the main causes of the damage, existing levee reinforcement structure 1b will be applied to levee 5 only to increase the flow rate (volume of water) flowing down river 3.

If the levee 5 is strong, the hybrid vertical water cut-off wall 25 (partition wall 13 of the support piles 9) will not be necessary, as described above. Furthermore, the reinforcement structure 1b for the existing levee is designed to resist the load transmitted from the deck slab 11 with the ground reaction force of the levee 5 and the reaction force of the support piles 9.

If the levee 5 is strong and can withstand all of the main causes of damage, a deck 11 and parapet 31 are constructed to increase the pocket (volume) of flow that flows down the river 3 and prevent water from overflowing the unbreakable levee and causing a flood.

A cushioning material (such as asphalt mat or asphalt mastic; not shown) may be placed between the deck slab 11 and the top 6 of the embankment 5 to fill the gap. Furthermore, a key 61 may be constructed as the most reliable fail-safe structure. This key 61 may be made of cast-in-place concrete, various precast materials, or sheet pile-type tablets.

Fourth Embodiment
The reinforcement structure 1c for an existing levee according to the fourth embodiment shown in Figure 12 differs from the reinforcement structure 1 for an existing levee according to the first embodiment of the present invention in that a support 63 is used instead of the first support pile 7, but in other respects it is configured in the same way as the reinforcement structure 1 for an existing levee, and it is possible to make modifications that are almost the same as those to the reinforcement structure 1 for an existing levee.

The reinforcement structure 1c for an existing embankment according to the fourth embodiment is composed of a support body 63, support piles 9, a deck slab 11, a partition wall 13, and a parapet 31.

The support 63 is installed along the embankment 5 (in the longitudinal direction of the embankment), with its upper section exposed from the embankment 5, its middle section recessed into the embankment 5, and its lower section recessed into the ground 15 below the embankment 5. The lower end of the support 63 abuts against the upper surface of the hard ground 27, but as shown by the dashed line, the lower end of the support 63 may also recess into the hard ground 27. It is also desirable that the support 63 be made of concrete or the like, like the key 61.

Multiple support piles 9 are installed. The upper and middle sections of the support piles 9 are exposed, while the lower sections are driven into the ground 15 outside the embankment 5, thereby embedding the piles. The multiple support piles 9 are installed in the ground 15 at predetermined intervals along the length of the embankment 5.

The deck 11 is located between the supports 63 and the support piles 9 in the width direction of the embankment 5, extends longitudinally along the embankment 5, and is installed integrally with the supports 63 and the support piles 9 at the upper part (e.g., the upper end surface) of the supports 63 and the upper part (e.g., the upper end surface) of the support piles 9 above the embankment 5. The deck 11 extends horizontally or in a direction close to horizontal, and the thickness direction of the deck 11 is generally vertical.

In addition, the existing levee reinforcement structure 1c is provided with partition walls 13. The partition walls 13 are installed between multiple support piles 9 along the levee 5 (in the longitudinal direction of the levee) and close the spaces between the multiple support piles 9.

In addition, in the reinforcement structure 1c for an existing levee, the partition walls 13 provided between the support piles 9 may be eliminated. In this case, it is desirable for the support bodies 63 to function as water-stopping walls. In other words, it is desirable for the support bodies 63 to be provided continuously along the length of the levee 5, allowing them to function as water-stopping walls.

Fifth Embodiment
The reinforcement structure 1d for an existing levee according to the fifth embodiment shown in Figure 13 differs from the reinforcement structure 1 for an existing levee according to the first embodiment of the present invention in that the existing levee 5 on which it is to be installed is an excavated levee, but in other respects it is configured in the same way as the reinforcement structure 1 for an existing levee, and it is possible to make modifications that are almost the same as those to the reinforcement structure 1 for an existing levee.

The fifth embodiment of the reinforcement structure 1d for an existing embankment is composed of first support piles 7, second support piles 9, a deck slab 11, a partition wall 13, and a parapet 31.

The upper part of the first support pile 7 is exposed from the embankment (a trenched embankment) 5, the middle part is recessed into the embankment 5, and the lower part is recessed into the ground 15 below the embankment 5. The upper part of the second support pile 9 is also exposed from the embankment 5, the middle part is recessed into the embankment 5, and the lower part is recessed into the ground 15 below the embankment 5.

The deck slab 11 is located between the first support pile 7 and the second support pile 9 in the width direction of the embankment 5, extends longitudinally along the embankment 5, and is installed integrally with the first support pile 7 and the second support pile 9 at the upper part (e.g., the upper end surface) of the first support pile 7 and the upper part (e.g., the upper end surface) of the second support pile 9 on the upper side of the embankment 5, and extends horizontally or in a direction close to the horizontal.

The partition wall 13 is installed along the embankment 5 between at least one of the first support piles 7 and the second support piles 9, enclosing the space between the support piles 7, 9. The partition wall 13 may also be omitted.

In addition, in the reinforcement structure 1d for the existing embankment, the underside of the deck slab 11 is either joined to the top 6 of the embankment 5 via a hood (not shown) or joined directly to the top 6 of the embankment 5.

Sixth Embodiment
The reinforcement structure 1e for an existing embankment according to the sixth embodiment shown in Figure 14 differs from the reinforcement structure 1d for an existing embankment according to the fifth embodiment of the present invention in that the deck slab 11 is located above the embankment 5 and separated from the embankment 5, but in other respects it is configured in the same way as the reinforcement structure 1d for an existing embankment, and it is possible to make modifications that are almost the same as those to the reinforcement structure 1d for an existing embankment.

Here, we will further explain the above-mentioned existing levee reinforcement structures 1 to 1e, etc.

Levees 5 on rivers 3, banks and embankments of flood control basins that temporarily store water during floods, and banks and embankments of reservoirs and reservoirs used for water storage are "soil structures" whose primary purpose is to stop water (water barrier).

Structures such as river levees with embankments, reservoirs, retarding basins, and dams are "soil structures intended to stop water (water impermeability)" that use soil as their primary construction material.

The hydraulic characteristics of river levees are that high water levels are temporary, not long-term, and they subside over a short period of time. As a result, water infiltration into the levee body is "unsteady (unsteady seepage flow)."

The hydraulic characteristics of reservoirs, reservoirs, and flood control basins designed for water storage are such that the water level is maintained at a near-constant level for a long period of time. This results in water infiltration into the embankment being "steady state (steady infiltration flow)."

Reservoirs and reservoirs are under the jurisdiction of the Ministry of Agriculture, Forestry and Fisheries, and the failure modes of their embankments can be broadly divided into three categories: seepage failure due to piping, as shown by reference number 313 in Figure 15; sliding failure due to the seepage of precipitation or stored water; and overflow failure due to overflow or overflow erosion (see dashed line 315 in Figure 15). The reinforcement structures 1 to 1e for existing embankments described above can prevent the above-mentioned failures.

In the reinforcement structures 1-1e of existing levees, the number of support piles 7, 9 is required to transmit the various loads transmitted from the load of the artificial deck 11, the load on top, and external forces acting to the support layer 27.

The hybrid vertical water cut-off walls 23 (25) may be arranged in a single row or in multiple rows. However, unlike the impermeable structures used in controlled waste landfills, the hybrid vertical water cut-off walls 23 (25) are intended to "stop water" rather than "water impermeable (block water)." There are no performance regulations for water leakage for hybrid vertical water cut-off walls 23 (25), as there are for controlled waste landfills. As a result, the structure of the hybrid vertical water cut-off walls 23 (25) only needs to be able to stop seepage water to a certain extent.

Therefore, the hybrid vertical water cut-off wall 23 (25) can fully perform its functions regardless of the material used, such as sheets, wooden boards, sheet piles, clay, steel plates, or concrete.

The "soil material" used for Levee 5 must be able to be used to construct a long levee inexpensively and in a short period of time, so sourcing high-quality soil material from a remote location would not meet the objectives and would generally be considered impossible.

As a result, most of the soil used for river levee 5 is from the area outside the levee near the point where it was transported by the river, and the soil material used for river levee 5 is primarily permeable material. This inevitably creates a structural weakness for river levee 5. However, with the reinforcement structures 1-1e for existing levees described above, even soil material used for river levee 5 can be prevented from being destroyed as described above.

The pile group (support piles 7 and 9, hybrid vertical water-stop walls 23 and 25) newly constructed as reinforcing structure 1 within levee 5 is expected to have seismic resistance effects, such as preventing liquefaction during earthquakes and increasing the strength of levee 5.

Note that the above-mentioned existing levee reinforcement structures 1, 1a, 1b, 1c, 1d, and 1e are examples of the following existing levee reinforcement structures:

That is, the first support is installed along the embankment with its upper section exposed, its middle section recessed into the embankment, and its lower section recessed into the ground below the embankment, or with its upper and middle sections exposed and its lower section recessed into the ground inside the embankment, and the second support is installed along the embankment outside the first support with its upper section exposed, its middle section recessed into the embankment, and its lower section recessed into the ground below the embankment, or with its upper and lower sections exposed and its lower section recessed into the ground outside the embankment. This is an example of a reinforcement structure for an existing levee, in which either or both of the first and second supports (at least one of the first and second supports) function as a water cut-off wall to block water flowing inside the levee.

1a, 1b, 1c, 1d, 1e Reinforcement structure of existing levee 5 Levee (embankment body)
6 Top edge 7 First support pile 9 Second support pile 11 Deck slab 13 Partition wall 15 Ground 31 Parapet 61 Key 63 Support

Claims (3)

a key having an exposed upper portion and a recessed lower portion along the bank;
a plurality of support piles installed at predetermined intervals along the embankment, with upper and middle sections exposed and lower sections embedded in the ground below the embankment outside the embankment;
a deck slab that is provided between the key and the support pile in the width direction of the embankment, extends long along the embankment in the longitudinal direction of the embankment, and is installed between the key and the support pile at the upper part of the key and the upper part of the support pile in the up-down direction, and extends horizontally or in a direction close to the horizontal direction;
a partition wall installed between the plurality of support piles along the embankment and enclosing the gap between the plurality of support piles;
A reinforcement structure for an existing embankment, characterized by having: a support installed along the embankment, with an upper portion exposed, a middle portion recessed into the embankment, and a lower portion recessed into the ground below the embankment;
a plurality of support piles installed at predetermined intervals along the embankment, with upper and middle portions exposed and lower portions embedded in the ground outside the embankment;
a deck slab that is provided between the support body and the support pile in the width direction of the embankment, extends long along the embankment in the longitudinal direction of the embankment, and is installed between the support body and the support pile at the upper part of the support body and the upper part of the support pile in the vertical direction, and extends horizontally or in a direction close to the horizontal direction;
a partition wall installed between the plurality of support piles along the embankment and enclosing the gap between the plurality of support piles;
A reinforcement structure for an existing embankment, characterized by having: a support member having an upper portion exposed, a middle portion recessed into the embankment, and a lower portion recessed into the ground below the embankment, the support member being provided continuously in the longitudinal direction of the embankment;
a plurality of support piles installed at predetermined intervals along the embankment, with upper and middle portions exposed and lower portions embedded in the ground outside the embankment;
a deck slab that is provided between the support body and the support pile in the width direction of the embankment, extends long along the embankment in the longitudinal direction of the embankment, and is installed between the support body and the support pile at the upper part of the support body and the upper part of the support pile in the vertical direction, and extends horizontally or in a direction close to the horizontal direction;
A reinforcement structure for an existing embankment, characterized by having: