JPH047406A - Method for laying underdrainage pipe - Google Patents

Abstract

PURPOSE:To realize an underdrain structure which is free from getting blocked and excellent in drainability by completely surrounding the periphery of an underdrainage pipe composed of a perforated pipe with cylindrical aggregates of crushed pumice having a specific gravity lower than 1. CONSTITUTION:After a trench having a rectangular cross section is dug into the ground, an underdrainage pipe 11 composed of a perforated pipe is laid in the trench in the length direction, with the periphery of the pipe 11 being surrounded with four cylindrical aggregates 12 formed by putting crushed pumice having a specific gravity lower than 1 and diameters smaller than 25 mm in fine-mesh polyethylene nets 21, and the trench is refilled with the excavated soil and sand. Since the aggregates 12 have the specific gravity lower than that of water, water quickly passes through the aggregates 12 and flows into the pipe 11 in a clean state. Therefore, an underdrain function which is free from getting blocked and excellent in drainability can be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction method for constructing a culvert drainage pipe, and more particularly to a construction method that provides excellent drainage performance without causing clogging.

Problems to be solved by the conventional technology and invention are shown in Figure 3.
A drawing schematically illustrating a conventional culvert drainage pipe installation method is shown.

For example, when installing culvert drainage pipes at a golf course, etc.
As shown in the figure, a trench with a rectangular cross section is excavated and a perforated pipe (
A crushed stone layer 32 with a specific gravity of about 1.6 made of crushed stone is held approximately in the center while holding an underdrain pipe 31 for drainage consisting of a perforated pipe).
form. Next, on the crushed stone layer 32, a mountain sand layer 33 made of sufficiently compacted soil or mountain sand and having a specific gravity of about 1.2 is formed.

In the above-described construction method for underdrain drainage pipes, since the specific gravity of the mountain sand layer 33 is greater than the specific gravity of water, the permeated water flows into the crushed stone layer 32 while slowly permeating through the mountain sand layer 33. Also,
Since the specific gravity of the crushed stone layer 32 is also considerably larger than the specific gravity of water, the water flowing into the crushed stone layer 32 forms a flow with a high velocity in the upper layer of the crushed stone layer 32. In other words, the permeated water flows through the mountain sand layer 3.
The water containing the earth and sand flows into the underdrain pipe 31 along with the earth and sand on the high-velocity flow in the upper layer of the crushed stone layer 32. As a result, there was a problem in that the underdrain pipe 31 became clogged and drainage performance was impaired.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a construction method for constructing an underdrain drainage pipe that has excellent drainage performance without clogging.

According to the present invention, a cylindrical lightweight crushed stone aggregate made of lightweight crushed stone is formed in advance, and excavation is carried out so that a drain pipe is completely surrounded by the cylindrical lightweight crushed stone aggregate. To provide a method for laying an underdrain drainage pipe, which is characterized in that an underdrain pipe for drainage is laid in a trench, and soil is backfilled around the cylindrical lightweight crushed stone aggregate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the culvert drainage pipe laying method of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic diagram illustrating an embodiment of the method for laying an underdrain drainage pipe according to the present invention. According to the construction method of the present invention, first, a trench having a rectangular cross section is excavated as in the conventional construction method. Next, 4 is made of lightweight crushed stone and has a specific gravity of less than 1.
Two cylindrical lightweight crushed stone aggregates 12 completely surround a drainage underdrain pipe 11 made of a perforated pipe. The excavation depth is determined by four cylindrical lightweight crushed stone aggregates 12 as shown in the figure.
It is best to make it slightly deeper than the height of the layers.

As shown in FIG. 2, the lightweight crushed stone aggregate 12 can be formed by, for example, filling a fine mesh polyethylene net 21 with lightweight crushed stones 22 preferably having a diameter of 25 mm or less in advance at a factory or on site. Finally, the gap around the cylindrical lightweight crushed stone aggregate 12 is backfilled with earth and sand.

In the construction method of the present invention, since the specific gravity of the lightweight crushed stone aggregate 12 is smaller than the specific gravity of water, permeated water quickly permeates through the lightweight crushed stone aggregate 12 and always remains clean as it flows through the underdrain pipe 11.
It will flow into the.

As the lightweight crushed stone, it is preferable to use Aqua Soil (trade name, manufactured by Ikegami Shoten Co., Ltd.), which is a known soil conditioner. Aqua Soil is a granular material made by crushing pearl rock into granules and foaming and firing them at high temperatures, as well as a fixing agent necessary for plant growth.
This is a well-known soil conditioner containing trace elements such as minerals, fluorine, manganese, and molybdenum. Further, details of Aquafil are described in Utility Model Application Publication No. 186150/1983. The specific gravity of a lightweight crushed stone aggregate using AquaSoil is approximately 0.55. Aqua Cube is a lightweight crushed stone aggregate formed by pre-packing Aquafil with a diameter of 25 mm or less into a fine mesh polyethylene net.
It is commercially available under the trade name (manufactured by Ikegami Shoten Co., Ltd.).

In this example, a method of completely surrounding the underdrain pipe with four cylindrical lightweight crushed stone aggregates was shown, but it is also possible to completely surround the underdrain pipe with three cylindrical lightweight crushed stone aggregates stacked in a triangular shape. It is clear that it can be done. It is also clear that the underdrain pipe can be completely surrounded by five or more cylindrical lightweight crushed stone aggregates.

Effects of the Invention As described above, in the underdrain drainage pipe installation method of the present invention, the specific gravity of the lightweight crushed stone aggregates surrounding the underdrain pipe is smaller than the specific gravity of water, so permeated water flows quickly and the underdrain remains clean at all times. Since the water flows into the pipe, it will not become clogged and therefore the drainage performance will not be impaired.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram illustrating an embodiment of the underdrain drainage pipe laying method according to the present invention, FIG. 2 is a diagram schematically showing the structure of a columnar lightweight crushed stone aggregate, and FIG. The figure is a schematic diagram illustrating a conventional method of constructing a culvert drainage pipe.

Claims (3)

[Claims] (1) A cylindrical lightweight crushed stone aggregate made of lightweight crushed stone is formed in advance, and a drainage underdrain pipe is installed in the excavated trench so that the drainage underdrain pipe is completely surrounded by the cylindrical lightweight crushed stone aggregate. A method for laying an underdrain drainage pipe, comprising: laying the pipe, and backfilling soil around the cylindrical lightweight crushed stone aggregate. (2) The construction method according to claim 1, wherein the cylindrical lightweight crushed stone aggregate is formed by packing lightweight crushed stones with a diameter of 25 mm or less into a fine mesh polyethylene net. (3) Claim (1) characterized in that the drainage underdrain pipe is completely surrounded by four cylindrical lightweight crushed stone aggregates.
) or the method described in (2).