JP2002121720A - Levee drain structure and its construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To forms a drain structure with high drainage ability without using a great amount of coarse grain material for a levee. SOLUTION: On the river back side of a dam body 2, a cage drain part 15 allowing inflow of seepage water from the dam body 2 is formed of filling cages 24 and 25 constructed by filling steel assembled nets with coarse grain filter material. Drain layers 16 and 17 are formed by fully covering a foundation ground 20 between the cage drain part 15 and a dam foot water passage 9 in the back toe and slope with the coarse grain filter material, and the cage drain part 15 and the drain layers 16 and 17 are covered with dam body soil 10. In this way, seepage water flowing into the cage drain part 15 is led to the bank foot water passage 9 via the drain layers 16 and 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drain structure for embankments and a method for constructing the structure.

[0002]

2. Description of the Related Art Drain works are one of the measures against water leakage from river embankments. In other words, because the infiltration water of the embankment causes the strength of the embankment to decrease, a drain section is provided at the bottom of the embankment so that the infiltration water of the embankment can be quickly discharged. is there. The infiltration water of the embankment includes river water that infiltrates from the front slope of the embankment and rainwater that infiltrates from the top and back slopes, and also seepage water from the foundation ground of the embankment I do. As the drain structure, for example, a structure composed of a back drainage with high drainage at the back of the embankment and a pier waterway at the bottom of the butt following this back stairwell is known. It is led to the lower berm and drains from there to the dike channel.

[0003]

However, in order to form a back step having a high drainage property capable of draining the seepage water of the embankment without delay, a large amount of a filter material having high water permeability is required. Becomes difficult. In other words, it is desirable to use a coarse-grained material having a diameter of 50 mm or more in order to enhance the drainage of the back small step. However, it is difficult to obtain such a coarse-grained material in large quantities near the construction site, and such coarse-grained material is difficult to obtain. Granular materials are difficult to compact and the slopes are difficult to form.

Further, it is conceivable to form the back small step with a material having low water permeability and to coat the back slope with an empty stone, but the workability is improved, but the drainage property is deteriorated.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention is to provide a drain part having a high drainage property without using a large amount of coarse particles by using a steel assembly network. Moreover, it facilitates construction.

That is, the present invention provides a drain structure of a dike formed on the back side of the embankment so as to drain the infiltration water of the embankment, wherein the coarse filter material through which the infiltration water passes is made of steel. A basket drain portion formed by a filling basket filled in the assembling net, and infiltrating water of the embankment; a pier waterway provided at a rear end of the embankment; A drain layer that is formed by a coarse-grained filter material that passes therethrough, connects a lower portion of the cage drain portion and the pier channel, and guides permeated water flowing into the cage drain portion to the pier channel, The drain layer is covered with embankment soil.

[0007] In the drain structure of the embankment, the seepage water of the embankment flows into the drainage section made of the cage, and is discharged therefrom through the drain layer to the embankment channel. That is, since the filter material of the basket drain portion is a coarse-grained material and the gap between the filter materials is large, the infiltrated water flowing down the gap and collects at the lower portion, and flows out to the drain layer from there. Become. The filter material constituting this drain layer is also a coarse-grained material, and the infiltration water flows smoothly toward the pier channel. In addition, the seepage water flows into the drainage part and the drain layer made of the cage from the foundation ground of the embankment body, and is discharged to the pier canal.

[0008] Thus, since the filter material of the basket drain portion is wrapped by the steel assembling net, even if it is a coarse-grained material, it does not collapse and its compaction becomes unnecessary. By stacking such filling baskets, a tall basket drain portion can be formed, and even if the embankment is high, the seepage water of the embankment can be reliably guided to the basket drain portion. . In addition, since such a filling basket has high stability, it is advantageous for securing the strength of the embankment body.

In addition, since the drain layer constituted by the filter material is covered with the embankment soil, even if a back step is formed on this drain layer, the construction is easy and the drainage property is improved. Is secured.

[0010] An excavation surface that descends toward the back of the river is formed on the embankment on the front side of the river from the drain portion made of the basket, and a filter material that allows permeated water to pass between the excavation surface and the drain portion made of the cage is filled. In this case, the seepage water of the embankment flows from the filter material to the basket drain portion.

[0011] Under the basket drain section and the drain layer,
In addition, it is preferable to lay a suction-preventing material that allows water to pass through and does not allow fine earth and sand to pass through the excavation surface. As a result, when infiltration water flows from the embankment and the foundation ground to the basket drain portion and the drain layer, the trickle earth and sand is prevented from flowing into the gap between the filter materials at the same time, thereby preventing the filter material from being clogged. Is done.

Further, the invention of this application is a method of constructing a drain structure of a dike provided on the backside of the embankment so as to drain the seepage water of the embankment. A step of forming an excavation surface that descends from the front side to the backside of the river and reaches the foundation ground of the embankment, and a step of laying a suction prevention material that allows water to pass through the excavation surface and the foundation ground and does not allow fine-grained soil to pass through; On the suction-preventing material at the end on the excavation surface side of the foundation ground, a packing basket filled with a steel assembly net is filled with a coarse-grained filter material through which the seepage water passes, and the packed basket is placed in a river flow. Extending along, forming a basket drain portion, and forming a drain layer by laying a coarse-grained filter material having a predetermined thickness through which the seepage water passes on the suction-preventing material of the foundation ground. And draining the basket drain and the excavated surface A step of forming a front drain portion by filling the filter material through which the infiltration water passes between the stopper material, and a step of covering the front drain portion, the basket drain portion, and the drain layer with the embankment soil. It is characterized by having.

Therefore, by filling and laying the filter material, it is possible to form a drain structure having a high drainage property on the river back side of the embankment and advantageous for securing the strength of the embankment.

[0014]

As described above, according to the drain structure of the embankment according to the present invention, a basket-made drain portion is formed on the back side of the embankment by a filling basket formed by filling a steel assembly network with coarse-grained filter material. Then, the lower part of the drainage part made of the basket and the dike channel at the bottom of the embankment were connected by a drain layer composed of coarse-grained filter material, and this drain layer was covered with embankment soil. Without the need for coarse material,
A drain structure with high drainage properties can be obtained, and it is also advantageous for securing the strength of the embankment, and the stability of the embankment can be enhanced by discharging the permeated water of the embankment to the pier canal without interruption.

According to the invention relating to the construction method of the drain structure of the embankment of this application, the step of forming the above-mentioned excavated surface, the step of laying the suction prevention material, and the step of filling the steel assembly net with the coarse filter material are performed. Stacking the filling basket thus formed to form a cage drain portion, laying a coarse filter material with a predetermined thickness to form a drain layer, forming a front drain portion, and embankment soil. Since it has a covering step, it is possible to easily obtain a drain structure having a high drainage property on the river back side of the embankment and advantageous for securing the embankment strength by filling and laying the filter material.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

<Drain Structure of Embankment> In the embankment of a river shown in FIG. 1, 1 is a river water, 2 is an embankment, and the embankment 2 has a front small step 3 and a back small step 4. A water-impervious sheet 7 that blocks the permeation of river water into the embankment 2 is provided on the front small step 3 and the upper and lower front slopes 5 and 6 of the embankment 2. A still sheet pile (not shown) is driven. Upholstery is installed on the top end 11 of the embankment body 2, the upper back slope 12 from the top end 11 to the back berm 4, the lower back slope 13 from the back berm 4, and the back berm 4 to the back slope. Have been. Then, on the river back side of the embankment body 2, first to fourth drain portions 14 to 17 are provided from the vicinity immediately below the bottom of the upper back slope 12 to the back pier waterway 9. ing. These drain portions 14 to 17 are provided along the flow of the river, and the drain portions 14 to 17 are covered with the embankment soil 10.

The first drain portion 14 is a front drain portion formed of a fine filter material. The second drain portion 15 is a basket drain portion filled with a coarse filter material. The third drain portion 16 is provided on the foundation ground 20.
Is a drain layer formed by laying a coarse-grained filter material with a predetermined thickness on the substrate. The fourth drain portion 17 is also a basket drain portion filled with the coarse-grained filter material, and forms a drain layer similarly to the third drain portion 16. 4th
The cage shape of the drain portion 17 is different from that of the second drain portion 15.

More specifically, an excavation surface 21 descending from the front side to the back side of the river is formed near the boundary between the upper back slope 12 and the back step 4, and the lower end thereof is formed on the foundation ground of the embankment body 2. Has reached 20. As shown in FIG. 2, on the foundation ground 20 and the excavated surface 21, a suction prevention member 22 that allows water to pass through and does not allow fine-grained soil to pass is laid.

Then, the fine-grained filter material 23 is placed in the triangular cross-section pocket formed between the suction-preventing member 22 and the second drain portion 15 of the excavation surface 21 and having a width narrowing downward. And the first drain portion 1
4 are formed. The first drain portion 14 and the second drain portion 15 are formed at the same height. Sand is employed as the fine filter material 23.

The second drain portion 15 has filling baskets 24, 2
5 are formed on the suction-preventing member 22 of the foundation ground 20 in two vertically stacked layers. The filling baskets 24 and 25 are each formed by filling a steel assembly net with a coarse filter material 26. The steel assembly net has a hexahedral shape in which each surface is formed by a metal net panel in which a metal net is stretched on a metal frame. 50-200 m in diameter as coarse filter material 26
m gravels or split stones are used.

The third drain portion 16 is connected to the foundation ground 20.
A coarse-grained filter material 26 similar to that of the second drain portion 15 is laid on the suction-preventing material 22. The third drain portion 16 is lower (about １ ／ in thickness) than the height of the second drain portion 15.

The fourth drain unit 17 is connected to the third drain unit 1
6 is filled with a coarse filter material 26 similar to that of the second drain portion 15 in a basket having substantially the same height as the thickness of the cage 6.
7. The basket is a shallow one having a bottom net, side nets erected around the bottom net, and partition nets erected at appropriate intervals in the flow direction of the river inside.

The pier waterway 9 is formed by a U-shaped groove member 31 made of concrete. The wall of the U-shaped groove member 31 on the fourth drain portion 17 side has water permeability. Also, U
The mold groove member 31 is installed on a paving stone (crushed stone) 33.

Thus, the third drain portion 16 and the fourth
A drain portion 17 connects the lower portion of the second drain portion 15 and the pier channel 9.

Therefore, the permeated water of the embankment body 2 flows into the first drain portion 14 and passes through the gap of the fine filter material 23 to the second drain portion 14.
It flows into the drain part 15. And this influent is second
It flows down through the gap between the coarse filter materials 26 of the drain portion 15, flows into the third drain portion 16, and further flows into the third drain portion 16.
It flows out to the pier waterway 9 through the gap between the coarse filter material 26 of the drain part 16 and the fourth drain part 17. Also,
Second to fourth drain portions 15 to 17 from foundation ground 20
The infiltration water flows into the pier and is similarly discharged to the pier waterway 9. When infiltration water flows into the drain portion from the embankment body 2 or the foundation ground 20, the inflow of trickle earth and sand simultaneously is blocked by the suction prevention member 22, and clogging of the filter members 23 and 26 is avoided.

The filling baskets 24 and 25 of the second drain portion 15 contribute to the drainage of the seepage water and, together with the back small step 4, contribute to securing the strength of the embankment body. In addition, the amount of the coarse-grained filter material 26 depends on the amount of the second drain portion 15 and the fourth drain portion 1.
7 and the portion forming the third drain portion 16 may be ensured, and the impermeable or semi-permeable embankment soil 10 can be applied to the back small step 4. However, the amount of the coarse filter material 26 can be reduced.

<Method of constructing the drain structure of the embankment> The back slope of the existing embankment 2 is cut diagonally from the middle of the back slope 12 to form the excavation surface 21 and the base ground 20 of the embankment.
To expose.

A suction prevention member 22 is laid on the foundation ground 20 and the excavation surface 21.

The first-stage steel assembly net for the second drain portion 15 is placed side by side in the flow direction of the river on the suction prevention member 22 at the end of the foundation ground 20 on the excavation surface 21 side. The inside of the steel assembly net is filled with the coarse-grained filter material 26 to form the first-stage filling baskets 24. Even if each steel assembly network is filled with the coarse-grained filter material 26 after arranging all of the first-stage steel assembly networks, the installation and filling operations are performed by dividing into several construction blocks. Is also good.

A second-stage steel basket is installed on the first-stage basket 24, a coarse-grained filter material 26 is filled therein, and a wire mesh is covered. To form As in the case of the first-stage filling basket 24, even if the coarse-grained filter material 26 is filled after arranging all the steel assembly nets in the same manner as in the case of the first-stage filling basket 24, the second-stage filling basket 25 is formed every several construction blocks. The installation and filling operations may be performed. The first-stage steel assembly network is connected to the second-stage steel assembly network.

The baskets for the fourth drain portion 17 are arranged along the backside and filled with coarse grain filter material 26. In forming the fourth drain portion 17, even if the coarse-grained filter material 26 is filled after all the baskets are arranged, the installation and filling work may be performed for each of several construction blocks. Good.

A coarse-grained filter material 26 is laid on the suction preventing member 22 between the second drain portion 15 and the fourth drain portion 17 to form a third drain portion (drain layer) 16. On the other hand, the suction prevention member 22 on the excavation surface 21 and the second
A fine-grained filter material 23 is filled between the drain portion 15 and the drain portion 15.

The first to fourth drain portions 14 to 17
Is covered with embankment soil 10 and compacted to form a back small step 4.

It is necessary that the surface (wall) in contact with the fourth drain portion 17 has water permeability for the pier waterway 9.

Therefore, since it is not necessary to form the entire back small step 4 with the coarse filter material 26, the amount of the coarse filter material 26 can be reduced, and the back small step 4 can be used when the original embankment body is cut. Can be formed by backfilling the excavated soil generated in the above, the compaction and forming thereof can be easily performed, and the occurrence of earth removal can be avoided.

The second drain portion 15 may be formed of only one filling basket, three or more filling baskets may be stacked, or two or more filling baskets may be arranged in rows.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a drain structure of an embankment according to the present invention.

FIG. 2 is a perspective view showing the drain structure with a partial cross section and a part omitted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 River water 2 Embankment body 4 Back small step 9 Pier waterway 10 Embankment body soil 11 Top end 12 Back slope 13 Back slope 14 1st drain part (front drain part) 15 2nd drain part (cage drain part) 16 Third drain part (drain layer) 17 Fourth drain part (drain layer) 20 Foundation ground 21 Excavated surface 22 Suction prevention material 23 Fine filter material 24 Filled basket 25 Filled basket 26 Coarse filter material

Continuation of the front page (72) Inventor Kengo Kobayashi 1-21-2 Kitabukuro-cho, Omiya-shi, Saitama Prefecture Ministry of Construction Kanto Regional Construction Bureau River Department, River Control Division (72) Inventor Kan Moriya 1-5-1 Mikuni Honcho, Yodogawa-ku, Osaka-shi No. 25 F-term in Kyowa Harmotech Co., Ltd. (Reference) 2D018 AA00 DA00

Claims (4)

[Claims] 1. A drain structure of a dike formed on the back side of a bank so as to drain the seepage water of the bank, wherein the coarse filter material through which the seepage water passes is connected to a steel assembly network. A cage-made drain portion formed by a filled filling basket and allowing the infiltration water of the embankment to flow in; a dike channel provided at the back of the embankment; and a coarse-grained passage through the infiltration water. A drain layer formed of a filter material, connecting a lower part of the cage drain portion and the pier channel, and guiding permeated water flowing into the cage drain portion to the pier channel; and Drain structure of embankment covered by body soil. 2. The drain structure of an embankment according to claim 1, wherein an excavation surface descending toward the back of the river is formed in the embankment on the front side of the river with respect to the drainage portion made of the cage, and Drain structure of the embankment filled with filter material that allows seepage water to pass between the cage drain part. 3. The drain structure of an embankment according to claim 2, wherein a suction-preventing material that allows water to pass through and prevents fine-grained sediment from passing is provided under the cage-made drain portion and under the drain layer and on the excavation surface. The drain structure of the embankment. 4. A method of constructing a drain structure of an embankment provided on the back side of a bank so as to drain permeated water of the embankment, wherein the back side of the embankment goes from the front side to the back side of the river. Forming an excavated surface down to the foundation ground of the embankment in accordance with the following; laying a suction-preventing material that allows water to pass through the excavated surface and the foundation ground and does not allow fine-grained soil to pass through; and the excavated surface of the foundation ground A step of forming a basket drain portion by stacking a filling basket filled with a steel assembly net with coarse filter material through which the seepage water passes, on the suction prevention material at the side end; and A step of forming a drain layer by laying a coarse-grained filter material having a predetermined thickness through the permeated water on the suction prevention material, and between the cage drain portion and the suction prevention material on the excavated surface. Through the above seepage water Step and, the front drain unit, the construction method of the drain structure of the dike and a step of covering the cage made of drain region and a drain layer at embankment earth to form a pre-drain unit by filling the timber.