JP7640852B2 - Embankment reinforcement structure - Google Patents

Description

The present invention relates to a reinforcing structure for embankments.

There are concerns about the risk of river embankments and other structures being breached or destroyed due to cracks or subsidence of the embankment body caused by earthquakes, and erosion of the embankment body caused by overflowing water during floods. As a countermeasure against this, for example, Patent Document 1 describes a reinforcement structure for embankments in which steel sheet pile walls are cast into the slopes on both sides of the embankment in the width direction, extending in the continuous direction of the embankment, and the heads of each steel sheet pile wall are connected by tie rods. Such reinforcement structures using double steel sheet pile walls are known to be effective as a countermeasure against liquefaction, since the two rows of steel sheet pile walls suppress deformation and movement of the soil during an earthquake.

Meanwhile, Patent Document 2 describes a reinforcing structure for a levee in which the steel sheet pile wall on the water side of the double steel sheet pile wall is formed continuously, while the steel sheet pile wall on the opposite side of the water side is formed as discrete bracing, and the embedded length of the steel sheet pile wall on the water side reaches the bearing layer of the ground, while the bracing work on the opposite side of the water side is not embedded all the way to the bearing layer. By forming the steel sheet pile wall on the water side continuously and with an embedded length that reaches the bearing layer, deformation and movement of the soil during an earthquake can be suppressed, while the opposite side of the water side is formed discretely and with a shorter embedded length, which can reduce the amount of steel used and the labor required to drive the steel sheet piles.

JP 2003-13451 A Patent No. 5578140

Although research has progressed on reinforcing embankment structures using double steel sheet pile walls as a countermeasure against liquefaction during earthquakes, it cannot be said that a sufficient number of rational structures have been proposed to improve the strength of embankments in the event of overtopping or scouring caused by rising water levels. In the following explanation, "when the water level rises" refers to the possibility of overtopping and scouring occurring due to rising water levels.

The present invention aims to realize a rational structure for reinforcing embankments using double steel sheet pile walls to improve the strength of embankments during periods of flooding.

［２］上記第１の鋼矢板壁の曲げ剛性ＥＩ_１および上記第２の鋼矢板壁の曲げ剛性ＥＩ_２が式（ii）の関係を満たす、［１］に記載の堤防の補強構造。
ＥＩ_２＞ＥＩ_１ ・・・（ii）
［３］上記第２の鋼矢板壁を構成する鋼矢板の上記ｙ方向への曲げ剛性は、上記第１の鋼矢板壁を構成する鋼矢板の上記ｙ方向への曲げ剛性よりも高い、［２］に記載の堤防の補強構造。
［４］上記第１の鋼矢板壁では上記ｘ方向について所定の間隔で鋼矢板が間欠的に配置され、上記第２の鋼矢板壁では鋼矢板が連続的に配置される、［２］または［３］に記載の堤防の補強構造。
［５］上記第１の鋼矢板壁の根入れ長さＬ_１および上記第２の鋼矢板壁の根入れ長さＬ_２が式（iii）の関係を満たす、［１］から［４］のいずれか１項に記載の堤防の補強構造。
Ｌ_２＞Ｌ_１ ・・・（iii）
［６］上記第２の鋼矢板壁を構成する一部の鋼矢板の根入れ長さが上記第２の鋼矢板壁を構成する残りの鋼矢板および上記第１の鋼矢板壁を構成する鋼矢板の根入れ長さよりも長いか、または上記第１の鋼矢板壁を構成する一部の鋼矢板の根入れ長さが上記第１の鋼矢板壁を構成する残りの鋼矢板および上記第２の鋼矢板壁を構成する鋼矢板の根入れ長さよりも短い、［５］に記載の堤防の補強構造。
［７］上記第１の鋼矢板壁の曲げ剛性ＥＩ_１および上記第１の鋼矢板壁の根入れ長さＬ_１と、上記第２の鋼矢板壁の曲げ剛性ＥＩ_２および上記第２の鋼矢板壁の根入れ長さＬ_２とが式（iv）の関係を満たす、［１］から［６］のいずれか１項に記載の堤防の補強構造。

[1] A reinforcing structure for a levee comprising: a first steel sheet pile wall driven into a part of the levee body facing the water area; a second steel sheet pile wall driven into a part of the levee body facing away from the water area; and a connecting member connecting the heads of the first steel sheet pile wall and the second steel sheet pile wall, wherein, when the longitudinal direction of the levee body is defined as the x direction and the horizontal direction perpendicular to the x direction is defined as the y direction, a bending stiffness EI ₁ of the first steel sheet pile wall in the y direction and an embedded length L ₁ of the first steel sheet pile wall, and a bending stiffness EI ₂ of the second steel sheet pile wall in the y direction and an embedded length L ₂ of the second steel sheet pile wall satisfy the relationship of formula (i) for average values per unit length in the x direction.

[2] The embankment reinforcement structure according to [1], wherein the bending stiffness EI ₁ of the first steel sheet pile wall and the bending stiffness EI ₂ of the second steel sheet pile wall satisfy the relationship of formula (ii).
EI ₂ > EI ₁ ...(ii)
[3] A reinforcement structure for a levee described in [2], wherein the bending rigidity in the y direction of the steel sheet piles constituting the second steel sheet pile wall is higher than the bending rigidity in the y direction of the steel sheet piles constituting the first steel sheet pile wall.
[4] A reinforcing structure for a levee described in [2] or [3], in which steel sheet piles are intermittently arranged at a predetermined interval in the x-direction in the first steel sheet pile wall, and steel sheet piles are continuously arranged in the second steel sheet pile wall.
[5] The embankment reinforcement structure according to any one of [1] to [4], wherein the embedded length _L1 of the first steel sheet pile wall and the embedded length _L2 of the second steel sheet pile wall satisfy the relationship of formula (iii).
L ₂ >L ₁ ...(iii)
[6] A reinforcement structure for a levee described in [5], wherein the embedded length of some of the steel sheet piles constituting the second steel sheet pile wall is longer than the embedded length of the remaining steel sheet piles constituting the second steel sheet pile wall and the steel sheet piles constituting the first steel sheet pile wall, or the embedded length of some of the steel sheet piles constituting the first steel sheet pile wall is shorter than the embedded length of the remaining steel sheet piles constituting the first steel sheet pile wall and the steel sheet piles constituting the second steel sheet pile wall.
[7] The embankment reinforcement structure according to any one of [1] to [6], wherein the bending stiffness EI ₁ of the first steel sheet pile wall and the embedment length L ₁ of the first steel sheet pile wall, and the bending stiffness EI ₂ of the second steel sheet pile wall and the embedment length L ₂ of the second steel sheet pile wall satisfy the relationship of formula (iv).

The above configuration allows for a rational structure to be realized that improves the strength of the embankment during floods by increasing the bending rigidity or lengthening the embedded length of the second steel sheet pile wall, which is subject to a larger moment when erosion and scouring occur on the slope opposite the water area of the embankment due to overflow during floods.

1 is a schematic cross-sectional view showing a reinforcement structure for an embankment according to a first embodiment of the present invention. FIG. 2 is a perspective view showing an example of a structure of a steel sheet pile wall in the reinforcement structure shown in FIG. 1 . FIG. 2 is a perspective view showing another example of the structure of a steel sheet pile wall in the reinforcement structure shown in FIG. 1 . FIG. 4 is a schematic cross-sectional view showing a reinforcement structure for an embankment according to a second embodiment of the present invention. FIG. 5 is a perspective view showing an example of a structure of a steel sheet pile wall in the reinforcement structure shown in FIG. FIG. 5 is a perspective view showing another example of the structure of a steel sheet pile wall in the reinforcement structure shown in FIG. FIG. 5 is a perspective view showing yet another example of the structure of a steel sheet pile wall in the reinforcement structure shown in FIG. FIG. 1 is a diagram showing a state set in an analysis for verifying the effect of a reinforcement structure for a levee according to an embodiment of the present invention.

A preferred embodiment of the present invention will be described in detail below with reference to the attached drawings. Note that in this specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, and redundant explanations will be omitted.

Figure 1 is a schematic cross-sectional view showing a reinforcing structure for a levee according to a first embodiment of the present invention. In this embodiment, the reinforcing structure for a levee 10 includes a first steel sheet pile wall 11 driven into the water area 2 side of the levee body 1, a second steel sheet pile wall 12 driven into the water area 2 side of the levee body 1, and a tie rod 13 which is a connecting member connecting the heads of the first steel sheet pile wall 11 and the second steel sheet pile wall 12. Here, the levee body 1 has a slope 1A on the water area side, a slope 1B on the opposite side to the water area, and a top surface 1C. The first steel sheet pile wall 11 is driven into the slope shoulder which is the boundary between the slope 1A on the water area side and the top surface 1C, or in the vicinity thereof, and the second steel sheet pile wall 12 is driven into the slope shoulder which is the boundary between the slope 1B on the opposite side to the water area and the top surface 1C, or in the vicinity thereof. The first steel sheet pile wall 11 and the second steel sheet pile wall 12 each extend in the longitudinal direction (x direction) of the embankment body 1.

In this embodiment, a tie rod 13 is used as the connecting member, but the connecting member is not particularly limited as long as it connects the first steel sheet pile wall 11 and the second steel sheet pile wall 12 and is capable of transmitting tensile and shear forces. In other embodiments, the connecting member may be a concrete top plate installed across the heads of each steel sheet pile wall, or a steel wall installed perpendicular to each steel sheet pile wall.

In this embodiment, the bending rigidity _EI2 of the second steel sheet pile wall 12 is larger than the bending rigidity _EI1 of the first steel sheet pile wall 11 ( _EI2 > _EI1 ). Here, the bending rigidities _EI1 and _EI2 are bending rigidities in the horizontal direction (y direction) perpendicular to the longitudinal direction (x direction) of the bank body 1. The bending rigidities _EI1 and _EI2 are calculated as average values per unit length in the longitudinal direction (x direction) of the bank body 1. That is, the bending rigidities _EI1 and EI2 are calculated by multiplying the Young's moduli E1 and _E2 of the material of the steel sheet piles constituting each steel sheet pile wall by the second moments of area _I1 and _I2 about the axis in the y direction within the range of the unit length in the _x direction of _each steel sheet pile wall.

Fig. 2 is a perspective view showing an example of the structure of a steel sheet pile wall in the reinforcement structure shown in Fig. 1. In the illustrated example, the bending rigidity of the steel sheet pile constituting the second steel sheet pile wall 12 is higher than that of the steel sheet pile constituting the first steel sheet pile wall 11. Here again, the bending rigidity is the bending rigidity in the horizontal direction (y direction) perpendicular to the longitudinal direction (x direction) of the embankment body 1. More specifically, for example, the steel sheet pile constituting the second steel sheet pile wall 12 has a larger moment of area about the axis in the y direction when forming a steel sheet pile wall than the steel sheet pile constituting the first steel sheet pile wall 11. As a result, for example, even if the first steel sheet pile wall 11 and the second steel sheet pile wall 12 are both formed continuously in the longitudinal direction (x direction) of the embankment body 1 and the embedded lengths L of the first steel sheet pile wall 11 and the second steel sheet pile wall 12 are substantially the same, the bending rigidity EI ₂ of the second steel sheet pile wall 12 becomes larger than the bending rigidity EI ₁ of the first steel sheet pile wall 11.

3 is a perspective view showing another example of the structure of the steel sheet pile wall in the reinforcement structure shown in FIG. 1. In the illustrated example, in the first steel sheet pile wall 11, missing parts 11X are formed at a predetermined interval P in the longitudinal direction (x direction) of the bank body 1. That is, in the first steel sheet pile wall 11, the steel sheet piles are intermittently arranged at a predetermined interval P. The interval P does not necessarily have to be the same for all the missing parts 11X, and may be different, for example, three steel sheet piles in one place that are arranged between the missing parts 11X to form the first steel sheet pile wall 11, and four steel sheet piles in another place. On the other hand, in the second steel sheet pile wall 12, such missing parts are not formed, and the steel sheet piles are continuously arranged. As a result, if the unit length _x1 is set to be equal to or greater than the interval P of the missing parts 11X formed in the first steel sheet pile wall 11 in the x direction, the second moment of area _I1 of the first steel sheet pile wall 11 in the range of the unit length _x1 is reduced by the amount of the missing parts 11X. As a result, for example, even if the first steel sheet pile wall 11 and the second steel sheet pile wall 12 are both constructed of steel sheet piles of the same material and cross section, and the embedded lengths L of the first steel sheet pile wall 11 and the second steel sheet pile wall 12 are substantially the same, the bending rigidity EI ₂ of the second steel sheet pile wall 12 will be greater than the bending rigidity EI ₁ of the first steel sheet pile wall 11.

4 is a schematic cross-sectional view showing a reinforcement structure of a levee according to a second embodiment of the present invention. In this embodiment, the reinforcement structure of the levee includes a first steel sheet pile wall 11 driven into the water area 2 side of the levee body 1, a second steel sheet pile wall 22 driven into the water area 2 side of the levee body 1, and a tie rod 23 which is a connecting member connecting the heads of the first steel sheet pile wall 21 and the second steel sheet pile wall 22. The first steel sheet pile wall 21 and the second steel sheet pile wall 22 each extend in the longitudinal direction (x direction) of the levee body 1. The embedded length _L2 of the second steel sheet pile wall 22 is longer than the embedded length _L1 of the first steel sheet pile wall 21 ( _L2 > _L1 ). Here, the embedded lengths _L1 and _L2 are calculated as average values per unit length in the longitudinal direction (x direction) of the levee body 1.

Figures 5 to 7 are perspective views showing examples of the structure of the steel sheet pile wall in the reinforcement structure shown in Figure 4. In the example shown in Figure 5, the embedded length _L2 of the entire second steel sheet pile wall 22 is longer than the embedded length L1 of the entire first steel sheet pile wall _21. On the other hand, in the example shown in Figure 6, the embedded length L21 of some steel sheet piles 221 constituting the second steel sheet pile wall ₂₂ is longer than the embedded lengths L22, L1 of the remaining steel sheet piles 222 constituting the second steel sheet pile wall 22 and the steel sheet piles constituting the first steel sheet pile wall ₂₁ ( _{L22 = L1} in the example of Figure 6). 7, the embedded length L11 of some of the steel sheet piles 211 constituting the first steel sheet pile wall 21 is shorter than the embedded lengths _L12 , L2 ( _L12 = _L2 in the example of FIG. 7) of the remaining steel sheet piles 212 constituting the first steel sheet pile wall 21 and the steel sheet piles constituting the second steel sheet pile wall 22. In these cases, too, the embedded length _L2 of the second steel sheet pile wall 22 is longer than the embedded length L1 of the first steel sheet pile wall 21 ( _L2 > _{L1 )} in terms of the average value per unit length in the longitudinal direction (x _direction ) of the embankment ₁ .

The first and second embodiments of the present invention described above can be combined with each other. That is, for the first steel sheet pile wall (bending rigidity EI ₁ , embedded length L _{1 ) installed in the water area side of the embankment in the embankment reinforcement structure, and the second steel sheet pile wall (bending rigidity EI 2, embedded length L 2 ) installed} in the water area side of the embankment, EI ₂ > EI ₁ and L ₂ > L ₁ may be satisfied. In the first embodiment, EI ₂ > EI ₁ and L ₂ = L ₁ , and in the second embodiment, EI ₂ = EI ₁ and L ₂ > L _1. The conditions including these can be expressed by the following formula (1). Specifically, it is only necessary to ensure sufficient bending rigidities EI ₁ , EI ₂ and embedded lengths L ₁ , L ₂ for the first steel sheet pile wall 11 and the second steel sheet pile wall 12, respectively, in terms of design, and then select an appropriate magnitude relationship from the above options.

From the viewpoint of more effectively improving the strength of the embankment, it is more preferable that the condition of formula (2) is satisfied. The condition of formula (2) is satisfied, for example, when the bending stiffness EI ₂ is 10% or more greater than the bending stiffness EI ₂ , or when the embedded length L ₂ is 10% or more greater than the embedded length L _1. For example, hat-shaped steel sheet piles constituting the steel sheet pile wall are known to be 10H type, 25H type, 45H type, and 50H type, in order of decreasing bending stiffness, and there is a difference in bending stiffness of at least 10% between each type. Therefore, when the second steel sheet pile wall is constructed of a type of steel sheet pile having a bending stiffness greater than that of the first steel sheet pile wall, the condition of formula (2) is satisfied when the bending stiffness EI ₂ is 10% or more greater than the bending stiffness EI ₂ .

The reasons why a levee reinforcement structure that meets the above conditions improves the strength of the levee during flooding are explained below.

When the river floods, water overflows from the water area side and flows over the levee to the opposite side. When overflow occurs, erosion and scouring progress on the slope 1B (see FIG. 1; the same below) of the levee body 1 on the opposite side of the water area 2, and the levee body 1 no longer has the effect of suppressing the deformation of the second steel sheet pile wall 12 on the opposite side of the water area 2. This causes different behaviors in response to horizontal loads such as flood loads between the second steel sheet pile wall 12 on the opposite side of the water area 2 and the first steel sheet pile wall 11 on the water area 2 side. Specifically, the moment generated in the second steel sheet pile wall 12 is larger than that in the first steel sheet pile wall 11, and the range of influence of the moment is deeper in the second steel sheet pile wall 12 than in the first steel sheet pile wall 11. Even if erosion and scouring of the slope 1B occurs due to overtopping, the deformation of the first steel sheet pile wall 11 is still suppressed by the embankment 1 between the first steel sheet pile wall 11 and the second steel sheet pile wall 12, so the moment generated is small and the range of influence of the moment is also shallow. By transmitting the load applied to the second steel sheet pile wall 12 to such a first steel sheet pile wall 11 by the tie rod 13, part of the moment of the second steel sheet pile wall 12 can be borne by the first steel sheet pile wall 11.

When considering the behavior during flooding as described above, applying the above conditions allows the second steel sheet pile wall 12 to withstand a larger moment, while for the first steel sheet pile wall 11, steel sheet piles with lower rigidity than the steel sheet piles that make up the second steel sheet pile wall 12 can be constructed with a wall extension or embedment depth sufficient to withstand a relatively smaller moment, making it possible to rationally design the embankment reinforcement structure.

Conventionally, embankment reinforcement structures using double steel sheet pile walls have been studied mainly as a measure against liquefaction during earthquakes, and therefore erosion and scouring of the slope on the opposite side of the water area when overtopping occurs have not been taken into consideration, and the first and second steel sheet pile walls have been designed to behave symmetrically against the flow force caused by liquefaction during earthquakes, or to behave the same against horizontal loads such as flood loads. In this case, it is not necessary to make the bending stiffness and embedded length of the first and second steel sheet pile walls different, and rather, as opposed to the above embodiment, the amount of steel used and the labor hours required for driving the steel sheet piles have been reduced by forming the steel sheet pile wall on the opposite side of the water area discretely or shortening the embedded length, as described above. Although such conventional embankment reinforcement structures using double steel sheet piles are also effective as a measure against liquefaction during earthquakes, the configuration according to the embodiment of the present invention described above is advantageous for a rational design that takes into account the strength of the embankment during floods.

In the embodiment described above, the second steel sheet pile on the opposite side of the water area is described as a continuous wall, but gaps between the steel sheet piles are acceptable if it is possible to prevent soil from flowing out of the embankment during floods, and joints do not necessarily have to be fitted between the steel sheet piles. In addition, although embankments of rivers and other structures are long, the reinforcing structure as in the embodiment described above does not necessarily have to be formed over the entire length of the embankment, as long as it is formed in a section that allows the average bending stiffness and embedded length of the steel sheet pile wall per unit length in the longitudinal direction of the embankment to be calculated. In addition, the steel sheet pile wall in the above embodiment can be replaced in part or in whole with a wall formed of a material other than steel sheet piles, such as PC sheet piles.

The following describes the results of an analysis verifying the effect of the embankment reinforcement structure according to the embodiment of the present invention. In the following analysis, the maximum bending moment for the horizontal load acting on the upper end of the steel sheet pile wall in the embankment reinforcement structure was calculated for each of the conditions A to C shown in Figure 8. In the analysis, the embankment was modeled at 1/15 scale, with the embankment base width of 2.0 m, the top width of 0.4 m, and the height of 0.4 m. The steel sheet pile walls were installed on the slopes on the water side (outside the embankment) and the opposite side to the water side (inside the embankment), respectively, with an embedded depth of 0.9 m. The steel sheet piles that make up each steel sheet pile wall are different, as shown in Table 1. Condition A shown in Figure 8 (A) is a state in which no overtopping has occurred and the slope of the embankment on the opposite side to the water area is preserved. Condition B shown in Figure 8 (B) is a state in which overtopping has occurred and the slope of the embankment on the opposite side to the water area has disappeared due to erosion. State C, shown in Figure 8 (C), is a state in which overflow continues from state B, causing scouring to a depth of 150 mm on the opposite side of the water area.

As shown in Table 1 above, in case 1, both the steel sheet pile walls on the outside and inside of the embankment were formed in a shape modeled on a 1/15 scale of a 10H hat-shaped steel sheet pile. In the case of the 10H type, the second moment of area per meter of wall width (the dimension in the longitudinal direction of the embankment body) of the steel sheet pile wall is approximately 10,000 cm ⁴ /m. On the other hand, in case 2, the steel sheet pile wall on the outside of the embankment was formed in a shape modeled on a 1/15 scale of a 10H hat-shaped steel sheet pile as in case 1, while the steel sheet pile wall on the inside of the embankment was formed in a shape modeled on a 1/15 scale of a 25H hat-shaped steel sheet pile. In the case of the 25H type, the second moment of area per meter of wall width of the steel sheet pile wall is approximately 25,000 cm ⁴ /m. Therefore, in case 2, the bending rigidity of the steel sheet pile wall on the inside of the embankment is greater than the bending rigidity of the steel sheet pile wall on the outside of the embankment. In Case 3, the steel sheet pile walls on both the outer and inner sides of the embankment were formed using a shape modeled on a 1/15 scale of a 25H hat-shaped steel sheet pile.

Table 2 shows the results of calculating the maximum bending moment M _max [kN/m] generated in each steel sheet pile wall in conditions B and C, and the allowable stress ratio in each case (long-term allowable stress was set to 197 MPa). The results for condition A are omitted because the maximum bending moment and allowable stress ratio are even smaller than those for condition B. In condition B, where the slope of the embankment body on the opposite side to the water area has disappeared due to erosion, the allowable stress is below 1 in all cases 1 to 3, but in condition C, where scouring has occurred, the allowable stress exceeds 1 on both the outside and inside of the embankment in case 1. This is thought to be because the deformation of the steel sheet pile wall on the inside of the embankment became excessive due to the disappearance of the slope and scouring, and a large load was also applied to the steel sheet pile wall on the outside of the embankment through the tie rod. On the other hand, in case 2, although the maximum bending moment generated in the steel sheet pile wall on the inside of the embankment in condition C exceeded that of case 1, the allowable stress did not exceed 1 because the steel sheet pile wall was formed of a hat-shaped steel sheet pile with a high bending rigidity of 25H. In addition, in Case 2, the high rigidity of the steel sheet pile wall on the inside of the embankment suppresses deformation, so the load on the steel sheet pile wall on the outside of the embankment via the tie rods is also reduced, and the allowable stress level of the steel sheet pile wall on the outside of the embankment, which is formed with 10H hat-shaped steel sheet piles, did not exceed 1. Even in Case 3, where both steel sheet pile walls were formed with 25H hat-shaped steel sheet piles, the allowable stress levels of the inside and outside of the embankment in condition C did not exceed 1, but in Case 2, the steel sheet pile wall on the outside of the embankment is formed with 10H hat-shaped steel sheet piles, which is advantageous in that the amount of steel used is reduced.

The above results show that making the bending rigidity of the second steel sheet pile wall greater than that of the first steel sheet pile wall, between the first steel sheet pile wall driven into the water side (outside of the embankment) of the embankment body and the second steel sheet pile wall driven into the opposite side of the water (inside of the embankment), in the embankment reinforcement structure is effective in improving the strength of the embankment during floods. Here, in order to be able to receive the expected resistance force from the ground even when the embedded depth is reduced due to scouring, in addition to or instead of increasing the bending rigidity as described above, the embedded length of the second steel sheet pile wall can also be made longer than that of the first steel sheet pile wall, which similarly improves the strength of the embankment during floods.

The above describes in detail preferred embodiments of the present invention with reference to the attached drawings, but the present invention is not limited to these examples. It is clear that a person skilled in the art of the technical field to which the present invention pertains can come up with various modified or revised examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

1... embankment body, 1A, 1B... slope, 1C... top surface, 2... water area, 10, 20... reinforcement structure, 11, 21... first steel sheet pile wall, 11X... missing part, 12, 22... second steel sheet pile wall, 13... tie rod, 211, 212, 221, 222... steel sheet pile.

Claims (6)

a first steel sheet pile wall to be installed in the water area side portion of the embankment;
A second steel sheet pile wall is installed on a portion of the embankment opposite to the water area; and
a connecting member connecting the head portions of the first steel sheet pile wall and the second steel sheet pile wall,
When the longitudinal direction of the bank body is defined as an x direction and a horizontal direction perpendicular to the x direction is defined as a y direction, a bending rigidity _EI1 of the first steel sheet pile wall in the y direction and an embedded length _L1 of the first steel sheet pile wall, and a bending rigidity EI2 of the second steel sheet pile wall in the y direction and an embedded length _L2 of the second steel sheet pile wall satisfy a relationship of Formula ( iv ) for average values per unit length in the _x direction ,
The second steel sheet pile wall is composed of a type of steel sheet pile having a bending rigidity 10% or more greater than that of the steel sheet pile constituting the first steel sheet pile wall , in a reinforcing structure of a levee.
The embankment reinforcement structure according to claim 1 , wherein the bending stiffness EI ₁ of the first steel sheet pile wall and the bending stiffness EI ₂ of the second steel sheet pile wall satisfy the relationship of formula (ii).
EI ₂ > EI ₁ ...(ii) The embankment reinforcement structure according to claim 2, wherein the bending stiffness in the y direction of the steel sheet piles constituting the second steel sheet pile wall is higher than the bending stiffness in the y direction of the steel sheet piles constituting the first steel sheet pile wall. a first steel sheet pile wall to be installed in the water area side portion of the embankment;
A second steel sheet pile wall is installed on a portion of the embankment opposite to the water area; and
A connecting member that connects the head portions of the first steel sheet pile wall and the second steel sheet pile wall;
Equipped with
A reinforcing structure for a levee, in which, when the longitudinal direction of the embankment body is defined as the x direction and the horizontal direction perpendicular to the x direction is defined as the y direction, the first steel sheet pile wall has steel sheet piles intermittently arranged at predetermined intervals in the x direction, and the second steel sheet pile wall has steel sheet piles continuously arranged, so that, for average values per unit length in the x direction, a bending stiffness EI1 of the first steel sheet pile wall in the y direction _and an embedded length L1 _of the first steel sheet pile wall, and a bending stiffness _EI2 of the second steel sheet pile wall in the y direction and an embedded length L2 of the second steel sheet pile wall _satisfy the relationship of formula (iv) .
The embankment reinforcement structure according to any one of claims 1 to 4, wherein the embedded length _L1 of the first steel sheet pile wall and the embedded length _L2 of the second steel sheet pile wall satisfy the relationship of formula (iii).
L ₂ >L ₁ ...(iii) The embankment reinforcement structure of claim 5, wherein the embedded length of some of the steel sheet piles constituting the second steel sheet pile wall is longer than the embedded length of the remaining steel sheet piles constituting the second steel sheet pile wall and the steel sheet piles constituting the first steel sheet pile wall, or the embedded length of some of the steel sheet piles constituting the first steel sheet pile wall is shorter than the embedded length of the remaining steel sheet piles constituting the first steel sheet pile wall and the steel sheet piles constituting the second steel sheet pile wall.

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