JP2575518B2 - Gravity sabo dam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a gravity type sabo dam using concrete.

<Conventional Technology> Conventional sabo dams have a structure that resists external forces such as water and earth and sand by the weight of unreinforced concrete.

Therefore, in order to prevent the sliding and overturning of the embankment and to make use of the characteristics of concrete with extremely low tensile strength, the structure becomes extremely large, and its weight must be made more than necessary in order not to generate internal tensile stress. Did not get.

Therefore, when the ground at the construction site is weak and sufficient bearing capacity cannot be expected, or when constructing a new sabo dam on already deposited soft runoff sediment (the sabo dam is In some cases, old dams are buried with sand and new dams can be built on them), and new sabo dams cannot be installed as they are, so it is necessary to improve the ground and strengthen the bearing capacity . Ground improvement was expensive and required construction time, so improvement was requested.

<Problems to be Solved by the Invention> An object of the present invention is to provide a gravity type sabo dam which has solved the above-mentioned problems.

<Means for Solving the Problems> The first invention is a gravity type sabo dam characterized by arranging a number of hollow steel corrugated pipes inside a bank body made of unreinforced concrete. A gravity type sabo dam characterized in that the steel corrugated pipe is arranged such that a pipe axis thereof coincides with a flow direction of water, earth and sand, and the like.

In a second aspect of the present invention, a gravitational sabo dam is provided, wherein the embankment is formed of a wall, and a large number of steel corrugated pipes are buried upstream of the wall, and earth and sand are backfilled between the corrugated pipes. It is.

<Operation> In the first invention, since a hollow portion is formed by disposing a steel corrugated pipe inside the embankment, as described later, cracks in the concrete are not generated from the hollow portion, and the hollow portion is formed. The weight of the embankment can be reduced by a minute.

Further, if the corrugated pipe is arranged so as to match the direction of flow of water, earth and sand, etc., the stress caused by external force of water, earth and sand, etc. can be borne by the corrugated pipe, and the internal stress of concrete can be reduced.

In the second invention, the adhesive force between the corrugated pipe buried on the upstream side of the wall and the backfilled earth and sand,
The corrugated pipe acts as an earth anchor and can support the wall 3.

In any of the first and second inventions, the weight of the embankment can be adjusted by selecting the number and diameter of the corrugated pipes to be arranged.

<Example> An example of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the first invention, and FIG. 2 is a front view of the same.

In FIGS. 1 and 2, reference numeral 1 denotes a bank body made of plain concrete. Reference numeral 2 denotes a steel corrugated pipe disposed inside the embankment body 1, and the pipe is not filled with concrete but is hollow. Thereby, the weight of the embankment 1 can be reduced by the hollow portion of the corrugated pipe 2.

Here, the reason why the corrugated pipe 2 is disposed inside the embankment body 1 is as follows.

If the hollow portion is provided only with concrete without disposing the corrugated pipe 2, tensile stress is inevitably generated due to stress concentration around the hollow portion, thereby causing cracking of concrete from the hollow portion and leading to breakage of the embankment 1. .

On the other hand, when the corrugated pipe 2 is arranged, since the corrugated pipe 2 and concrete are attached, the above tensile stress is applied to the corrugated pipe 2 (that is, the corrugated pipe 2 becomes a tensile material). ,
The generation of the cracks can be prevented.

The corrugated pipe has irregularities in the axial direction and is wider than a normal steel pipe having the same surface area and the same diameter, so that a larger adhesive strength can be secured.

The corrugated pipe itself can be used as a disposal form when creating the hollow part.

Next, a specific example of the first invention will be described with reference to FIGS.

A corrugated steel pipe with a nominal diameter of 2 m and a plate thickness of 3.2 mm (both the height and pitch of the wave is 50 mm) was placed on the embankment 1 made of plain concrete of the dimensions shown in FIG.
An example will be described in which the arrangement is made so as to coincide with the direction of the flow of the earth and sand, and the application is performed.

As shown in FIG. 4, the corrugated pipes 2 were arranged in an equilateral triangle such that the distance between the outer surfaces of two adjacent corrugated pipes was 1 m. The length was determined so that the horizontal distance from the corrugated end to the embankment surface was 3 m, that is, the slab thickness of the surface was 3 m on both the upstream and downstream sides.

As a result of FEM analysis and model tests on the above model under design external force based on the Ministry of Construction's Sabo Technical Standards, it was found that the internal stress was lower than the allowable stress of concrete and corrugate and safe. In addition, the embankment weight is about 25
% Reduction achieved.

 Next, FIG. 5 is a sectional view of an embodiment of the second invention.

In FIG. 5, reference numeral 3 denotes a dam wall made of concrete, and a large number of steel corrugated pipes 4 are embedded upstream of the wall 3. Reference numeral 5 denotes earth and sand backed between corrugated pipes. The corrugated pipe 4 acts as an earth anchor by the adhesive force between the corrugated pipe 4 and the earth and sand 5 to support the wall 3.

The reason for using corrugated pipes is that corrugated pipes have large irregularities on the surface, so they have excellent adhesion to backfill soil, can sufficiently support the front wall, and select the number and diameter of corrugated pipes. By doing so, the weight of the embankment can be concreted.

FIG. 6 is a sectional view of another embodiment of the second invention,
In this example, a masonry 6 is formed on the upstream surface of the embankment body using a snake cage.

 Next, a specific example of the second invention will be described.

When the weight of a levee body 7 with a levee height of about 25m as shown in Fig. 7 is reduced by about 25% while maintaining the required strength, backfill the soil 5 with the length of Fig. 5. do it. In this case, the amount of concrete is about 1/3 of the original amount, the newly required earth and sand is 380 m ² / m, and the corrugated pipe (φ = 2000 mm) is 30 ton / m.

<Effect of the Invention> As described above, according to the present invention, the weight of the embankment can be reduced without generating tensile stress on the embankment or without sacrificing the strength of the embankment. The present invention can be applied very advantageously to a case where the ground at the point is soft and sufficient ground strength cannot be expected, or a case where a new sabo dam is to be constructed on already deposited runoff sediment.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the first invention, and FIG. 2 is a front view of the same. FIG. 3 is a sectional view showing a specific example of the first invention, and FIG. 4 is a layout view of a corrugated pipe. FIG. 5 is a sectional view showing an embodiment of the second invention, FIG. 6 is a sectional view showing another embodiment of the second invention, and FIG. 7 is a sectional view showing an example of a conventional sabo dam. is there. 1 ... embankment, 2 ... steel corrugated pipe, 3 ... wall, 4 ... steel corrugated pipe, 5 ... earth and sand, 6 ...
Mason, 7 ... embankment.

Continued on the front page (72) Inventor Shinzo Utsunomiya 2-3-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Hibiya International Building Kawasaki Steel Corporation Tokyo Head Office (72) Inventor Seizou Nakamura 2-chome Uchisaiwaicho, Chiyoda-ku, Tokyo No. 3 Hibiya International Building Kawasaki Steel Corporation Tokyo Head Office (72) Inventor Yasuyoshi Akinaga 2-3-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Hibiya International Building Kawasaki Steel Corporation Tokyo Head Office

Claims (3)

(57) [Claims] (1) Inside a bank body made of unreinforced concrete,
A gravity type sabo dam characterized by a number of hollow steel corrugated pipes. 2. A gravity type sabo dam according to claim 1, wherein the steel corrugated pipe is arranged so that its pipe axis coincides with the direction of flow of water, earth and sand. 3. A gravity type sabo dam, wherein a bank is constituted by a wall, a number of steel corrugated pipes are buried upstream of the wall, and earth and sand are backfilled between the corrugated pipes.