JP2011214252A - Structure for reinforcing embankment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure for reinforcing an embankment by using a double-underground steel-wall body which enables constant drainage between double steel sheet-pile walls while inhibiting an outflow of soil.SOLUTION: The underground steel-wall bodies 2 and 3 are provided in at least two rows along the continuous direction of the embankment within the range of the almost upper surface 1c of the continuous embankment 1. The underground steel-wall bodies 2 and 3 are constituted by coupling steel sheet piles 4 to each other. The underground steel-wall body 3 includes a short steel sheet pile 8 which is coupled to the steel sheet pile 4 used for the underground steel-wall bodies 2 and 3 in the two rows for constituting a part of the underground steel-wall body 3, and shorter than the steel sheet pile 4. The short steel sheet piles 8, for example, are disposed one by one with a distance of about 10-20 m between each other. A height position of a lower end of the short steel sheet pile 8 is set at or near a height position of a lower end of the embankment 1.

Description

  The present invention relates to a reinforcement structure for embankments extending long along rivers, rivers such as rivers, railway embankments, roads, railways, and the like.

  In recent years, large earthquakes have frequently occurred in Japan, and several major earthquakes are predicted to arrive in the near future. In embankment structures such as river embankments, the basement due to liquefaction of the foundation ground due to the earthquake There are concerns about damage such as cracks and subsidence.

  As an earthquake countermeasure for embankment structures, the embankment method bottom (slope lower end) is often applied with ground improvement or steel sheet pile reinforcement, but the water level suddenly rises due to unexpected heavy rain, etc. In order to prevent osmotic breakage caused by breakage and bank breakage due to overflow, research is being conducted on a composite structure by installing steel sheet piles inside the levee body.

  As such a construction method, by placing steel sheet piles along the continuous direction of the levee body, respectively, on the left and right shoulder parts (slope upper end part) in the dam body (filling), a double steel sheet pile There has been proposed a structure in which a wall is installed and the heads of the left and right steel sheet pile walls are joined by tie rods (see, for example, Patent Document 1). According to this construction method, the subsidence of the levee body is suppressed during an earthquake, and furthermore, the steel sheet pile with excellent water shielding ensures the height of the dam body. This is an effective method for reinforcing embankment structures.

  Such embankment and river-side water penetrates into the embankment so as to go around the lower end of the double steel sheet pile wall, but rainwater and other water flowing into the double steel sheet pile wall is not drained and stored. There is concern. Then, the embankment reinforcement structure which makes it possible to always drain the water in the double steel sheet pile wall by providing water permeability to at least one steel sheet pile of the double steel sheet pile wall has been proposed. (For example, refer to Patent Document 2).

JP 2003-13451 A JP 2010-24745 A

  By the way, in the said patent document 2, the following various proposals are made | formed as a structure which gives water permeability to a steel sheet pile wall. For example, an example in which a water-permeable steel sheet pile with a hole is used is shown as a structure for imparting water permeability to a steel sheet pile wall. In addition, by providing a steel sheet pile wall using a steel sheet pile without a joint only at the upper part of the steel sheet pile wall, a gap is created in the connection portion between the steel sheet piles at the upper part of the steel sheet pile wall, and this gap allows water permeability to the steel sheet pile wall. An example of having In addition, the steel sheet piles have a structure with no joints over the entire length of the steel sheet piles. An example of a structure having properties is shown.

  Also, in one steel sheet pile wall of the double steel sheet pile walls, the steel sheet piles are not connected to each other, but are spaced apart from each other, and each steel sheet pile is connected to the other steel sheet pile wall with a horizontal connecting member. An example of a structure having high water permeability by connecting is shown. Similarly, in one steel sheet pile wall of the double steel sheet pile walls, the steel sheet piles are not connected to each other and arranged at intervals from each other, and each steel sheet pile is arranged along the length direction of the dike. The example which becomes a structure which has high water permeability by fixing with the H-shaped steel arrange | positioned horizontally is shown.

Here, the cost of the permeable steel sheet pile is increased by drilling the steel sheet pile.
Moreover, in the structure which has the gap along the length direction of the embankment on the upper side of the steel sheet pile, there is a possibility that the earth and sand in the embankment will flow out from the gap during an earthquake and overflow.
Moreover, in the state where the adjacent steel sheet piles are not connected, and the state where the upper part of the adjacent steel sheet piles is not connected, a reduction in the resistance force at the time of an earthquake is caused compared to the case where they are connected.

  In the structure in which the embankment is reinforced with an underground steel wall body such as a double steel sheet pile wall, the present invention can always drain between the double steel sheet pile walls while suppressing the outflow of earth and sand. An object of the present invention is to provide a reinforced embankment reinforcement structure.

  In order to solve the above-mentioned problem, the embankment reinforcing structure according to claim 1 is provided with underground steel wall bodies in two rows along the continuous direction of the embankment within the range of the approximate top end of the continuous embankment. The underground steel wall body is configured by connecting sheet piles that are steel sheet piles or steel pipe sheet piles, and at least one row of the underground steel wall bodies is one of the sheet piles constituting the underground steel wall body. As a part, a sheet pile shorter than other sheet piles (hereinafter, this sheet pile is also referred to as “short sheet pile”) is included.

  In invention of Claim 1, for example, in a steel (pipe) sheet pile wall (underground steel wall body) made of a long sheet pile (steel sheet pile and steel pipe sheet pile) to be embedded to the support ground, the wall body is configured. When a part of the sheet piles to be used are short sheet piles, there will be a gap between normal sheet piles arranged on the left and right of the short sheet piles, ensuring water permeability at this part, and two rows of underground steel walls The drainage of the ground between the bodies can be secured.

  In this case, since the head (upper end) of the sheet pile and the short sheet pile are substantially at the same position, a gap is created in the lower part of the underground steel wall body, and there is a gap in the underground steel wall body in the embankment portion. Sediment runoff is unlikely to occur in some cases. In particular, it is not easily affected by water overflow. Therefore, the drainage between the two rows of underground steel wall bodies can be secured while preventing the outflow of earth and sand. Moreover, all the sheet piles including a short sheet pile are connected, and even if a short sheet pile is used for a part, the proof strength with respect to an earthquake, a flood, etc. can be hold | maintained.

The embankment reinforcement structure according to claim 2 is the invention according to claim 1, wherein the embankment serves as a dike for a river or the like, and constitutes an underground steel wall body on the side far from the river or the like. A sheet pile shorter than other sheet piles is included as part of the sheet pile.
Here, the embankment of a river etc. shall include the embankment of a reservoir, a lake, a shore, etc. as well as the embankment of a river.

  In the invention of claim 2, drainage between two rows of underground steel wall bodies can be performed on the opposite side of the river or the like in a bank or the like. In addition, the side close to the river may be an underground steel wall that uses a short sheet pile. However, since there is water from the river, the drainage effect is smaller than the side far from the river, and the short sheet pile. If a large amount of is used, the water shielding effect as an underground steel wall against water inflowing into the river will be reduced. Therefore, it is not necessary to use a short sheet pile for the underground steel wall on the side close to the river or the like.

  The embankment reinforcing structure according to claim 3 is the invention according to claim 1 or 2, wherein the height position of the lower end of the sheet pile shorter than the other sheet pile is the height position of the lower end of the embankment or the vicinity thereof. It is characterized by being.

  In invention of Claim 3, since the lower end position of a short sheet pile is the height position of the lower end of embankment or its vicinity, the water collected between two rows of underground steel wall bodies of embankment part is collected. It can drain smoothly.

  According to the present invention, since a short sheet pile is used by mixing it with a normal length sheet pile constituting the underground steel wall body, between the sheet piles arranged so as to sandwich the short sheet pile, and the short sheet pile A gap is formed on the lower side, and water accumulated between the two rows of underground steel wall bodies can be drained using this gap. Moreover, since a gap is formed on the lower side of the steel sheet pile wall, it is possible to suppress outflow of earth and sand at the time of an earthquake or flood than when a gap is formed in a wide vertical range at the height of the bank. From the above, drainage between two rows of underground steel wall bodies can be made possible while suppressing the outflow of earth and sand from the embankment.

It is a schematic sectional drawing which shows the reinforcement structure of the embankment which concerns on embodiment of this invention. It is the schematic which shows the underground steel wall body which has the water permeability used for the reinforcement structure of the said embankment. (A) is a schematic sectional drawing of the reinforcement structure of the said embankment, (b) is the schematic of the said underground steel wall body. (A) is a schematic sectional drawing of the modification of the reinforcement structure of the said embankment, (b) is the schematic of the modification of the said underground steel wall body.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 3, the embankment reinforcement structure of this embodiment is for reinforcing a bank embankment such as a river embankment or road / railway embankment. I will explain. Slope 1a is formed on the left and right sides of the embankment 1 as a river bank. Further, the left side of the embankment 1 in the figure of the embankment 1 is a river 7.
In the reinforcement structure of the embankment 1, underground steel wall bodies 2 and 3 made of steel sheet pile walls in which steel sheet piles 4 (including steel pipe sheet piles) are connected within the range of the approximate top end 1 c of the embankment 1 are installed. Yes. Note that the range of the approximate top end 1c also includes the shoulder 1b portion that is the upper end of the slope 1a slightly outside the top end 1c.

The steel sheet pile 4 constituting the underground steel wall bodies 2 and 3 penetrates the embankment 1 and the foundation ground 5 immediately below the embankment 1 and has a depth to be embedded in the supporting ground. The continuous direction (length) of the embankment 1 Direction). The heads (upper end portions) of the underground steel wall bodies 2 and 3 are positioned at a height that is near the height of the top end 1 c of the embankment 1. In the reinforcement structure of the embankment 1, a structural skeleton portion 6 is formed in the embankment 1. The structural skeleton 6 is made of ground that is closed by underground steel wall bodies 2 and 3 provided in two rows.
Further, a connecting member such as a tie rod 9 is bridged between the upper ends of the two rows of underground steel wall bodies 2 and 3, and both ends thereof are fixed to the underground steel wall bodies 2 and 3, respectively. ing. A plurality of tie rods 9 are arranged at intervals in the length direction of the embankment 1. In addition, it is good also as a structure which does not provide a connection member.

In this embankment reinforcement structure, in order to prevent water such as rainwater from collecting between the two rows of underground steel walls 2, 3, One underground steel wall body 3 on the side far from the river 7 (inside the embankment) has water permeability.
Moreover, in one underground steel wall body 3, in addition to the steel sheet pile 4 of the length penetrated to the above-mentioned support ground, the height of the embankment 1 (from the lower end (the ground surface) to the top end) is almost the same. A short steel sheet pile 8 is used as a short steel sheet pile of the same length.

  In the underground steel wall body 3 including the short steel sheet piles 8, the short steel sheet piles 8 are arranged at intervals, and a plurality of steel sheet piles 4 are arranged between the short steel sheet piles 8. That is, in the steel sheet pile wall which consists of the steel sheet piles 4, it replaces with the steel sheet pile 4 every 10m-20m, for example, and the short steel sheet pile 8 is arrange | positioned. Further, the steel sheet pile 4 includes a short steel sheet pile 8 and is connected to each other by a joint to form an underground steel wall body 3 as a steel sheet pile wall. In the underground steel wall body 3, The short steel sheet pile 8 is connected to the left and right steel sheet piles 4.

In addition, when the arrangement | positioning space | interval of the short steel sheet pile 8 becomes narrow, for example, when narrower than about 10 m, there exists a possibility of causing the fall of the resistance force at the time of the earthquake of the underground steel wall 3. That is, when the number of the short steel sheet piles 8 included in the underground steel wall body 3 is increased, there is a possibility that the resistance force to the external force due to an earthquake or the like is reduced. Moreover, when the space | interval of the short steel sheet pile 8 becomes large, for example, when it is wider than about 20 m, the flow by the drainage of a wide range of water will concentrate on the part of the short steel sheet pile 8, and there exists a concern that the seepage failure of the embankment 1 may occur. There is.
However, depending on the rigidity of the steel sheet pile 4 and the length of the steel sheet pile 4 and the short steel sheet pile 8 and the situation of the foundation ground and the supporting ground, the appropriate interval between the short steel sheet piles 8 may change, and it is not necessarily from 10 m. 20 m is not an appropriate interval, and a shorter range or a longer range may be an appropriate interval.

In this embodiment, it is assumed that the permeability of the foundation ground 5 supporting the lower embankment 1 of the embankment 1 is considerably worse than the permeability of the embankment 1, and the height of the lower end of the short steel sheet pile 8 is assumed. The position is set slightly higher than the height position h of the lower end of the embankment 1.
Since the lower end of the short steel sheet pile 8 is higher than the foundation ground 5 and is disposed slightly above the lower end of the embankment 1 where the necessary water permeability can be expected, as shown in FIG. Below, drainage from the lower end of the embankment 1 above the foundation ground 5 becomes possible.

As indicated by the arrows in FIG. 1, there is a concern that a part of the earth and sand of the embankment 1 flows out from the lower end of the short steel sheet pile 8 at the time of an earthquake or flood as with the flow of the drainage. As compared with the case where there is a gap in the underground steel wall body so as to include many parts, the amount of earth and sand flowing out can be reduced. In this case, the amount of earth and sand flowing out can be reduced by widening the arrangement interval of the short steel sheet piles 8.
Here, if the permeability of the foundation ground 5 is not so bad compared to the permeability of the embankment, that is, if the permeability of the foundation ground 5 is relatively high and the water soaked in the embankment 1 can be drained through the foundation ground 5. For example, as shown in FIGS. 4A and 4B, it is preferable that the height position of the lower end of the short steel sheet pile 8 is arranged at a position lower than the lower end of the embankment 1.

In this case, since some degree of water permeability can be expected in the foundation ground 5, even if the height position of the upper end of the gap formed by the short steel sheet pile 8 is lower than the lower end portion of the embankment 1, two rows of underground steel Rainwater collected between the walls 2 and 3 can be drained, and the outflow of earth and sand from the embankment 1 can be reliably prevented.
As described above, the lower end position of the short steel sheet pile 8 is preferably determined based on the water permeability of the foundation ground 5, and when the permeability of the foundation ground 5 is considerably lower than the embankment 1, When the height position is set slightly higher than the lower end of the embankment 1 (the upper surface of the foundation ground 5) and the water permeability of the foundation ground 5 is not so bad with respect to the permeability of the embankment 1, it is set lower than the lower end of the embankment 1. .
Thereby, the further reduction of the outflow amount of the earth and sand of the embankment 1 at the time of an earthquake or flood can be aimed at.

In the embankment reinforcement structure as described above, even if a gap for drainage is formed in the underground steel wall body 3, the outflow of the earth and sand of the embankment 1 can be suppressed. The drainage property in the two rows of underground steel wall bodies 3 can be enhanced while suppressing the outflow.
Moreover, although the short steel sheet pile 8 will be used in addition to the normal steel sheet pile 4, except for the difference in length, the steel sheet pile 4 and the short steel sheet pile 8 are the same steel sheet pile, and the short steel sheet pile. However, the manufacturing cost is not higher than that of the steel sheet pile 4. Therefore, cost reduction can be aimed at rather than the case where the water-permeable steel sheet pile which has a water-permeable hole is used.

  Moreover, the steel sheet pile wall of this embodiment is the structure which replaced a part of steel sheet pile 4 with the short steel sheet pile 8 with respect to a normal steel sheet pile wall, and only the number using the short steel sheet pile 8 is a steel sheet pile. The weight of the steel material obtained by subtracting the weight of the short steel sheet pile 8 from the weight of 4 is reduced. Thereby, cost reduction of steel materials cost and construction cost can be aimed at.

  Moreover, the steel sheet pile 4 and the short steel sheet pile 8 used for the underground steel wall body 2 can use a U-shaped steel sheet pile, a hat-shaped steel sheet pile, a steel pipe sheet pile, a Z-shaped steel sheet pile, and the like.

1 Embankment 1c Top edge 2 Underground steel wall body 3 Underground steel wall body 4 Steel sheet pile (sheet pile)
8 Short steel sheet piles (shorter than other sheet piles)

Claims (3)

The underground steel wall bodies are provided in two rows along the continuous direction of the embankment within the range of the approximate top end of the continuous embankment,
The underground steel wall body is configured by connecting sheet piles that are steel sheet piles or steel pipe sheet piles,
The embankment reinforcing structure according to claim 1, wherein at least one row of the underground steel wall bodies includes a sheet pile shorter than other sheet piles as a part of the sheet pile constituting the underground steel wall body. The embankment serves as a dike for rivers,
The embankment reinforcement structure according to claim 1, wherein a sheet pile shorter than other sheet piles is included as a part of the sheet pile constituting the underground steel wall body on the side far from a river or the like.   The embankment reinforcement structure according to claim 1 or 2, wherein the height position of the lower end of the sheet pile shorter than the other sheet piles is the height position of the lower end of the embankment or the vicinity thereof.

Images