JP5817272B2 - Embankment reinforcement structure - Google Patents

Description

  The present invention relates to a reinforcing structure for embankment type embankments in rivers.

On both banks of large rivers, embankment type embankments are constructed as part of flood control measures. If the embankment breaks down during an earthquake or flood, it will cause serious damage to the coastal area, so it is necessary to take measures to prevent the embankment from collapsing.
As a conventional method for constructing a levee, there is a method of covering the surface of a levee with a surface material having a high water barrier property made of concrete, for example. According to this method, it is possible to suppress water penetration into the embankment and leakage from the embankment during a flood. However, since the strength of the dyke structure itself is not improved, it is not possible to prevent the levee from collapsing due to a large external force such as an earthquake or flood, or the levee from becoming unstable due to softening or deformation of the foundation ground. If the embankment collapses or drops in height, there is a problem that even if it is local, it leads to river flooding.

Moreover, since the surface material made of concrete covers the surface of the levee, it is impossible to prevent water leakage to the inside of the levee that occurs through the highly permeable formation below the levee. For this reason, it is necessary to place a sheet pile wall or the like for preventing water leakage on the base in the vicinity of the heel.
Patent Document 1 describes the “soft ground handbook” (Construction Industry Research Committee) and “liquefaction countermeasure design / construction manual (draft)” (Ministry of Construction) Cited structural examples of Civil Engineering Research Laboratories and others). Of these, Fig. 12 shows a dike constructed in a river. FIG. 12 (a) is quoted from the former and FIG. 12 (b) is quoted from the latter, but both have almost the same structure, and tie rods are installed between steel sheet piles placed facing the vicinity of the buttock.

  If a tie rod is installed, a water channel is easily formed. In order to avoid this, a self-supporting steel sheet pile can be placed instead of the tie rod installation. However, simply placing a steel sheet pile near Hoshiri will reduce the restraint force on the ground closed between the steel sheet piles, so if a large earthquake occurs, the embankment and ground will be completely deformed. It cannot be prevented, and as a result, the bank breaks and collapses. In addition, when a large-scale flood occurs over the embankment, there is a problem that the embankment collapses due to the influence of the water flow (for example, scouring, flooding, seepage, etc.).

A steel sheet pile placed near the shore of the embankment as shown in FIG. 12 has a low restraint force against the embankment, so that sufficient strength to prevent the embankment from collapsing due to these causes cannot be obtained.
In addition, it is pointed out that covering with concrete or the like not only damages the landscape but also destroys the natural environment.
The invention described in Patent Document 1 reaches the support ground from the top of the embankment in order to solve the above-mentioned problems without using a concrete surface material in consideration of such landscape and natural environment. A sheet pile wall that has been placed in this manner is formed.

  FIG. 13 is a cross-sectional view showing an embodiment of the invention described in Patent Document 1, in which two rows of sheet pile walls 2 and 3 are installed near the shoulders on both sides of the upper surface of the embankment B. The sheet pile walls 2 and 3 are connected by a connecting material 4. The embankment ground B and the foundation ground F are cut off inside the structural skeleton 5 composed of the sheet pile walls 2 and 3 and the connecting material 4 and the supporting ground S. Since the sheet pile walls 2 and 3 have their lower ends fixed to the supporting ground S and their upper ends are connected by the connecting material 4, the restraining effect of the embankment B is enhanced, and the stability of the levee 1 is enhanced. In this example, the bank R on the river R side is made of stone masonry, and the opposite side of the river R (the so-called private land side) covers the upper surface and slope of the bank R with a protective material.

  However, in this embankment, when rainwater or the like flows into the structural skeleton 5 from the upper surface of the embankment B, or when groundwater penetrates into the structural skeleton 5 due to aging of the sheet pile walls 2 and 3, the structural skeleton 5 Water stays in it for a long time. As a result, the embankment ground B and the foundation ground F in the structural skeleton 5 are loosened, and a water channel is formed in the vicinity of the sheet pile walls 2 and 3, which may damage or sink the structural skeleton 5. As a result, a gap is generated between the sheet pile walls 2 and 3 and the embankment B, and when an external force is applied to the dike 1 due to an earthquake or the like, the sheet pile walls 2 and 3 may be deformed.

JP2003-13451

  An object of this invention is to provide the reinforcement structure which can improve the stability of a dike with respect to various natural environments, such as a flood and an earthquake.

In the present invention, the river side sheet pile wall is driven to reach the supporting ground near the river side shoulder of the dike, and the private side sheet pile wall reaches the supporting ground near the private side shoulder of the dike. and pouring, a reinforcing structure of the embankment which is connected by a connecting member further installed horizontally and river side sheet pile wall and minced side sheet pile wall at the top of the embankment soil embankment, with foundation ground top of river side sheet pile wall For a certain foundation ground thickness T, the waterstop in the range from the top of the foundation ground to the T / 4 position to the top of the embankment is higher than that of the embankment, and the area within the embankment on the side of the ground pile is The embankment reinforcement structure has higher water permeability than the embankment and has higher permeability in the range of the foundation ground of the private side sheet pile wall than the foundation ground.

  In the reinforcing structure of the present invention, it is preferable that the permeability of the foundation ground near the private side of the embankment is higher than that of the foundation ground. Moreover, it is preferable that the part which touches the river channel side sheet pile wall and the private side sheet pile wall at the upper part of the embankment has higher water permeability than the embankment and has a high resistance to scavenging.

According to the present invention, by placing a sheet pile wall having a higher water-stopping capacity than the embankment on the river channel side of the embankment, water intrusion from the river channel side into the structural skeleton is suppressed, and in the event of flooding or an earthquake It is possible to prevent the destruction of the embankment by external force.
In addition, the following two effects can be expected by placing a sheet pile wall that is highly water-blocking in the embankment on the private land side and that is highly permeable in the foundation ground below the embankment.
(a) For flooding in the event of a flood, the sheet pile wall in the embankment has been improved in water-blocking to prevent the outflow of sediment from the structural skeleton due to water flow, maintaining the soundness of the structural skeleton, A significant disaster caused by a bank can be prevented.
(b) During rainfall or flooding, water accumulated in the structural skeleton can be quickly discharged from the part of the sheet pile wall in the highly permeable foundation ground, so that the formation of water channels and the subsidence of the structural skeleton Can be prevented.

  In addition, since this invention can be implemented by driving a sheet pile wall using the existing construction equipment, it can be applied to both newly installed levee and reinforcement of existing levee.

It is sectional drawing which shows typically the example which applied the present invention and reinforced the embankment. It is a top view of the embankment shown in FIG. It is sectional drawing which shows an example of a sheet pile wall with a high water stop. It is sectional drawing which shows the other example of a sheet pile wall with a high water stop. It is sectional drawing which shows an example of a sheet pile wall with high water permeability. It is sectional drawing which shows the other example of a sheet pile wall with high water permeability. It is sectional drawing which shows typically the other example which reinforced the embankment by applying this invention. It is sectional drawing which shows typically the other example which reinforced the embankment by applying this invention. It is sectional drawing which shows typically the other example which reinforced the embankment by applying this invention. It is sectional drawing which shows typically the other example which reinforced the embankment by applying this invention. It is sectional drawing which shows typically the other example which reinforced the embankment by applying this invention. It is explanatory drawing which shows the example of the conventional bank. It is explanatory drawing which shows the other example of the reinforcement structure of the conventional bank. It is sectional drawing which shows typically the other example which reinforced the embankment by applying this invention. It is sectional drawing which shows typically the other example which reinforced the embankment by applying this invention.

FIG. 1 is a cross-sectional view schematically showing an example in which a dike is reinforced by applying the present invention, and FIG. 2 is a plan view thereof.
A river-side sheet pile wall 2 is placed near the shoulder 11a on the river R side (hereinafter referred to as the river channel side) of the dike 1 so as to reach the support ground S. Further, the private side sheet pile wall 3 is placed so as to reach the support ground S near the shoulder 11b on the opposite side of the river R (hereinafter referred to as the private side). The supporting ground S is a strong rock, and supports the riverside side sheet pile wall 2 and the private side side sheet pile wall 3 by fixing them. On the other hand, the placement depth is set so that the upper end of the riverside sheet pile wall 2 and the private land sheet pile wall 3 is located on the upper surface of the embankment B. In other words, the river side sheet pile wall 2 and the private side sheet pile wall 3 have a depth that penetrates the embankment ground B constituting the embankment 1 and the foundation ground F below the embankment 1 and is placed on the support ground S. The levee 1 is continuously installed in the length direction. In addition, the embankment ground B is the ground embanked in constructing the embankment 1, and the foundation ground F is a soft ground or a liquefied ground.

And the river channel side sheet pile wall 2 and the private side sheet pile wall 3 are connected with the connection material 4 arrange | positioned in the horizontal direction in the upper part of the embankment B. The structure constituted by the river side sheet pile wall 2, the private side sheet pile wall 3, the connecting material 4, and the supporting ground S is referred to as a structural skeleton portion 5.
Since the river side sheet pile wall 2 and the private side sheet pile wall 3 have their lower ends fixed to the supporting ground S and their upper ends connected by the connecting material 4, the restraining effect of the embankment ground B in the structural skeleton 5 is high. As a result, the stability of the levee 1 is improved. Therefore, even when the embankment 1 cannot maintain the shape due to various factors during a flood or an earthquake, the height of the embankment 1 can be secured by the structural skeleton 5, so that flooding of the river can be prevented.

If steel sheet piles or steel pipe sheet piles are used as the river channel side sheet pile wall 2 and the private side sheet pile wall 3, since existing construction machines can be used, construction in a short period of time is possible. Further, when the dike 1 is already installed, it is not necessary to secure a new site for constructing the riverside sheet pile wall 2 and the private side sheet pile wall 3.
The embankment having the reinforcing structure of the present invention ensures stability against earthquakes depending on the strength of the structural skeleton 5 as a structure. The reason why stability is demonstrated against floods is explained below.

First, the river channel sheet pile wall 2 will be described.
As shown in FIG. 1, the river side sheet pile wall 2 penetrates the embankment B and the foundation ground F and is placed on the support ground S, and the water-stopping property in the range from the upper part of the foundation ground F to the upper surface of the embankment B. Is made higher than the embankment board B by means such as shown in FIGS. Specifically, it is desirable that the hydraulic conductivity is about 1/100 or less of the embankment B.

The upper part of the foundation ground F indicates a range of T / 4 from the upper end of the foundation ground F with respect to the thickness T of the foundation ground F.
By increasing the waterstop of the river side sheet pile wall 2 in the embankment bed B, water can be prevented from entering the embankment bed B in the structural skeleton 5 from the embankment bed B on the river channel side. Furthermore, by increasing the waterstop of the river side sheet pile wall 2 in the upper part of the foundation ground F in the same manner as in the embankment ground B, water enters the embankment ground B in the structural framework 5 from the foundation ground F on the river side. Can be suppressed.

  The river side sheet pile wall 2 only needs to increase the water stoppage in the range from the upper part of the foundation ground F to the upper surface of the embankment B, and does not necessarily need to be a sheet pile wall having a high water stop over the entire length in the depth direction of the levee 1. If the waterstop of the river side sheet pile wall 2 is increased over the entire length in the depth direction of the embankment 1, it will be difficult to discharge the water that has entered the embankment B on the river side, so it will act on the river side sheet pile wall 2 from the river side. The water pressure increases and the stability of the levee 1 is impaired. Therefore, the range from the lower part of the foundation ground F located below the part with high water-stopping to the part placed on the supporting ground S is not provided with means as shown in FIGS. To do. The same applies to the river-side sheet pile wall 2 in FIGS. 9 to 11 described later.

An example of a sheet pile wall having a high water-stopping property is shown in FIG. 3 as a cross-sectional view. As shown in FIG. 3, a steel sheet pile 21 is placed after a water-stopping material 22 (for example, water-expandable rubber, resin, etc.) is applied or attached in advance to the claw portion of the Larsen joint of the U-shaped steel sheet pile 21. By doing, a sheet pile wall with high water-stopping property is obtained.
FIG. 4 is a cross-sectional view showing another example of a sheet pile wall having a high water-stopping property. In the example of FIG. 4, the drain 23 is arranged on the river channel side of the steel sheet pile 21. The drain 23 is a water draining means and embeds a perforated pipe or the like. The water that has entered the embankment B from the river R flows out to the foundation ground F through this drain 23 before reaching the steel sheet pile 21. Since the foundation ground F is a soft ground as already explained, the water flowing out to the foundation ground F through the drain 23 permeates into the foundation ground F widely. As a result, the water pressure acting on the river channel sheet pile wall 2 from the river R side is reduced, and water can be prevented from penetrating into the embankment B in the structural skeleton 5.

Next, the private side sheet pile wall 3 will be described.
As shown in FIG. 1, the private side sheet pile wall 3 penetrates the embankment ground B and the foundation ground F and is placed on the support ground S. And the water permeability in the range in the foundation ground F is made higher than that of the foundation ground F by means as shown in FIGS.

By increasing the water stoppage of the private side sheet pile wall 3 in the embankment B, water can be prevented from penetrating into the structural skeleton 5 from the private side. However, it is impossible to prevent flooding, rainwater, and the like during a flood from penetrating into the structural skeleton part 5 from the upper surface of the embankment B, but it is possible to prevent the embankment B in the structural skeleton part 5 from flowing out due to the water flow.
The water that has entered the structural skeleton 5 is quickly discharged by increasing the water permeability of the private side sheet pile wall 3 in the foundation ground F, and penetrates widely into the foundation ground F. As a result, it is possible to prevent water from forming and sinking of the embankment B.

In addition, when the water permeability of the foundation ground F is relatively high, as shown in a cross-sectional view in FIG. You may extend to F upper part. The reason is to increase the effect of preventing water from penetrating into the structural skeleton 5 from the banking ground B on the private side.
Or, when the permeability of the embankment ground B is small, as shown in a cross-sectional view in FIG. 8, the portion where the permeability of the private side sheet pile wall 3 is increased is not limited to the foundation ground F, and the lower part of the embankment ground B It may be extended to. The reason is to enhance the effect of discharging water that has entered the structural skeleton 5.

It is desirable that the permeability coefficient of the highly permeable sheet pile wall is equal to or greater than the permeability coefficient of the foundation ground F.
As an example of a sheet pile wall with high water permeability, what provided the hole of the predetermined magnitude | size in the predetermined position of the steel sheet pile can be mentioned. Moreover, as shown as a side view in FIG. 5, a gap 33 may be formed by cutting a lower portion from a predetermined position of the joint portion 32 of the steel sheet pile 31 constituting the private side sheet pile wall 3. Good. Alternatively, as shown in FIG. 6 as a cross-sectional view, it is also possible to configure a private side sheet pile wall 3 having a highly permeable part by using a steel sheet pile 31 that does not have a fitting claw in the joint portion. is there. The steel sheet pile 31 as shown in FIG. 6 is not only reduced in manufacturing cost but also reduced in penetration resistance during construction, so that construction speed and construction accuracy are improved.

  FIG. 9 is a cross-sectional view schematically showing another example in which the present invention is applied to reinforce a dike. In other words, the foundation ground F in the vicinity of the shore 12 on the private side of the bank 1 shown in FIG. 1 is replaced with the highly permeable ground material 6. As a result, the water permeability of the foundation ground F in the vicinity of the private side bottom edge 12 becomes higher than that of the original foundation ground F, and the water that has penetrated into the structural skeleton 5 is discharged as indicated by the arrows. Sediment runoff near Hoshiri 12 can be suppressed. As shown in FIG. 9, it is preferable to provide the drainage groove 7 in the water-permeable ground material 6 because the drainage performance is further improved and the effect of suppressing the sediment discharge near the hose 12 is improved.

The water-permeable ground material 6 is desirably a ground material having a water permeability coefficient of about 0.05 cm / sec or more, and examples thereof include coarse sand and fine gravel. The water permeability coefficient of the water permeable ground material 6 is preferably 100 cm / sec or less.
FIG. 10 is a cross-sectional view schematically showing another example in which the dike is reinforced by applying the present invention. That is, in the embankment 1 shown in FIG. 1, the portion of the embankment 1 in contact with the river side sheet pile wall 2 and the private side sheet pile wall 3 at the upper part of the embankment B is higher in permeability than the embankment B and has a higher sweep resistance characteristic. Replace with 8. As a result, when the water level of the river R rises due to flooding, the embankment B in the structural skeleton 5 can be prevented from flowing out from the upper surface of the embankment B, and the river side sheet pile wall 2 and the private side sheet pile wall 3 It is possible to prevent water from being formed in the vicinity. The replacement material 8 is preferably sand gravel or coarse sand having a 20% particle size (D20) in the accumulation curve of about 0.5 mm or more and about 2 mm or less in consideration of water permeability and scavenging resistance characteristics.

The head resistance characteristic means a characteristic that resists the flow of water trying to push the earth and sand, and is evaluated by factors such as the specific gravity, surface area, and frictional force of the soil particles. The accumulation curve is a curve in which the logarithm of the particle diameter is on the horizontal axis, and the weight of the particle size or less is shown on the vertical axis as a percentage of the total weight.
In addition, when an external force is applied to the dike 1 due to an earthquake or the like, the river side sheet pile wall 2 and the private side sheet pile wall 3 tend to bulge outside the embankment ground B, and the embankment of the embankment ground B is relatively Since the repair is easy, only the upper portion of the embankment B on the inner side of the river side sheet pile wall 2 and the private side sheet pile wall 3 may be replaced with a replacement material 8 as shown in a sectional view in FIG.

  Moreover, when the embankment B contains a lot of clay components and the water permeability is relatively low, as shown in FIG. 14, the water stoppage of the area in the embankment B of the private side sheet pile wall 3 is not increased. You may comprise a sheet pile wall. Or as shown in FIG. 15, you may comprise the range in the embankment B of the private side sheet pile wall 3 and the full length of the river channel side sheet pile wall 2 with a normal sheet pile wall.

  It prevents water from penetrating into the structural skeleton from the river channel side of the embankment and preventing the destruction of the embankment due to external forces during floods and earthquakes. Moreover, since it can be carried out by placing a sheet pile wall using existing construction equipment, it can be applied to both new levees and reinforcement of existing levees, and thus has a remarkable industrial effect.

DESCRIPTION OF SYMBOLS 1 Embankment 2 River side sheet pile wall 3 Private side sheet pile wall 4 Connection material 5 Structural frame part 6 Permeable ground material 7 Drainage groove 8 Replacement material
11 shoulder
12 Houshiri
21 Steel sheet pile on river side sheet pile wall
22 Water stop material
23 Drain
31 Steel sheet pile on the side sheet pile wall
32 Joint
33 Crevice B Embankment F Foundation ground R River S Support ground

Claims (3)

The river side sheet pile wall is driven to reach the supporting ground near the river side shoulder of the dike, and the private side sheet pile wall is driven to reach the supporting ground near the private side shoulder of the dike. And a reinforcement structure of the levee in which the riverside sheet pile wall and the private side sheet pile wall are connected horizontally by a connecting material at the upper part of the embankment embankment, the foundation ground of the river side sheet pile wall With respect to the thickness T of the foundation ground, which is the upper part , the water stoppage in the range from the position of T / 4 from the upper end of the foundation ground to the upper end of the embankment is higher than that of the embankment, and the An embankment reinforcing structure characterized in that the water stoppage in the area within the embankment is higher than that in the embankment, and the water permeability in the area within the foundation ground of the private side sheet pile wall is higher than that of the foundation ground.   The reinforced structure for a levee according to claim 1, wherein the permeability of the foundation ground in the vicinity of the private bottom of the levee is higher than that of the foundation ground.   The portion of the upper part of the embankment that is in contact with the riverside sheet pile wall and the private side sheet pile wall is higher in water permeability than the embankment, and has high scavenging resistance characteristics. Or the embankment reinforcement structure of 2.

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