RU2399721C1 - Method for erection of horizontal drain - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method for erection of horizontal drain includes provision of intake, collection and draining parts. All structural parts of drain are made of flexible mats that consist of meshy shells and draining filler, which is made of tight alternating rows of light fascines and perforated pipes wrapped in geogrid. Water intake part of drain is made of mats laid normally towards direction of filtration flow. Inner water collection part of drain is made of mats laid in layers towards direction of filtration flow. Draining part is made of similar mats arranged in plan in horizontal strips, at a certain distance to each other towards direction of filtration flow and with inclination from water collection part down to foot of lower slope. Light fascines of mats are made with diametre of 15-20 cm and length of 2-2.2 m from dry ripe cane.

EFFECT: invention makes it possible to reduce labour intensiveness of drain manufacturing and to increase efficiency of its operation.

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Description

The invention relates to hydraulic engineering and land reclamation construction and can be effectively used as a drainage device for low-pressure earthen dams and dams.

The closest technical solution is the method of constructing horizontal drainage, arranged at the base of the lower slopes of earthen dams and dams, consisting of receiving and discharge parts made of sand-gravel filters (return filters), stone aggregate and discharge pipes [1]. The main disadvantages of this technical solution are:

- the need for a large amount of stone and gravel material;

- high complexity of manufacturing inverse filters;

- low construction efficiency.

The purpose of the invention is to reduce construction costs and increase work efficiency.

This goal is achieved by the fact that in the method of erecting horizontal drainage, including the receiving, catchment and discharge parts, all structural parts of the drainage are made of flexible mattresses consisting of mesh shells and a drainage aggregate, which is made of dense alternating rows of light fascines and perforated pipes wrapped in the geogrid, while the water intake part of the drainage is made of mattresses laid normally to the direction of the filtration flow, the inner drainage part is made of mattresses, laid layers in the direction of the filtration flow, and the outlet part is made of similar mattresses, but arranged in horizontal stripes in a plan and at a certain distance from each other in the direction of the filtration flow, and with a slope from the drainage part to the bottom of the bottom slope, moreover, light-weight fascines of mattresses are made with a diameter of 15-20 cm and a length of 2-2.2 m from dry ripened reeds.

Figure 1 shows a cross section of an earthen dam (dam) with horizontal drainage; figure 2 is a plan of a horizontal section of the drainage made in its middle; figure 3 - flexible mattress, consisting of a mesh shell and a draining aggregate, made of light fascia and perforated pipes; figure 4 is a light fascin of dry reeds.

The horizontal drainage consists of the intake part 1, the drainage part 2, the drainage part 3 made of flexible mattresses 4. The flexible mattress 4 consists of a mesh shell 5 (geogrid), a draining aggregate of alternating rows of light fascines 6 and perforated polymer pipes 7.

The method of construction of horizontal drainage is carried out and works as follows. According to the proposed method, light bowls 6 of dry reeds and flexible mattresses 4 are prepared in advance. After a wide trench is developed at the base of the lower slope (dam or dam), just above the bottom of the NB, by the overall dimensions of the drainage. Along the bottom of the trench, pre-prepared flexible mattresses 4 of the water intake part 1 are laid out in dense rows normal to the direction of the filtration flow along the entire width. On top of the horizontal rows of mattresses 4 of the water intake part 1, similar mattresses 4 of the water catchment part 2 are laid in two layers in the direction of the filtration flow. Then around the mattresses 4 of the catchment part 2 (on the sides and on top), the water intake part of the same mattresses 4, but located normally to the direction of the filtration flow, is being completed. Then, from the catchment part 2 with a slope of (0.05) to the downstream (NB) in the direction of the filtration stream, the same mattresses 4 of the drainage part 3 are laid in horizontal stripes. The width of the horizontal stripes of the drainage part 3, and the distance between them is taken from the provision free drainage of filtered water through an earthen structure.

Horizontal drainage works as follows.

Filtration water, moving under the influence of hydrostatic pressure from the upstream side (WB) through the pores of the soil body of the dam or dam, falls into the zone of the water intake part 1 of the drainage. Further, flexible mattresses 4 freely accept water because of their high water permeability and pass through light fascines 6 and perforated pipes 7 into the catchment part 2. And when filling the catchment part to the middle of its section, water easily flows from it into the drainage part 3 - into the drainage part trenches that accelerate the removal of filtered water into the sewer due to the good slope and gradient of the filtration flow. In the absence of water level in the NB, more efficient drainage operation is ensured. Therefore, the proposed design drainage is recommended to be used in medium and low-pressure soil dams and dams of land debris, when there is no water in the NB under normal operating conditions, or when there is a small level of water in the NB, which cannot affect the drainage operation mode. The presence of perforated pipes 7 in flexible mattresses 4 (of which all drainage is built) increases the drainage ability of the structure, extends the life of the drainage.

The efficiency of drainage mattresses increases if sandy or sandy-gravel soil is laid on top of them.

In the design of drainage mattresses, in addition to perforated pipes, dry reeds are used as drainage material - a sufficiently resistant and durable natural material that works effectively in an aqueous environment. Light fascia 6, wrapped in a geogrid, forming a water intake part 1 prevents filtration deformation of adjacent soils. This eliminates the removal and penetration of small particles of soil into flexible mattresses 4, due to the use of geogrid. Thus, safe reception and removal of filtered water through the body of earthworks is ensured at all possible operational water levels in the WB.

Horizontal drainage, built according to the proposed method, can work effectively without major repairs for 15-20 years. Due to the fact that dry ripened reeds are highly draining and sufficiently resistant material, which is able to stay in the aquatic environment for up to 20 years or more. The service life of dry reeds used for the manufacture of light fascia and mattresses can be extended twice if it is treated with a special solution that increases the water resistance of the material.

The proposed method of erecting horizontal drainage is recommended to be used on the flat sections of rivers during the construction and reconstruction of earthen dams and dams of landslide areas where there are not enough stone and gravel material. And also - in hard-to-reach places where the delivery of construction equipment is difficult.

The source of information

1. Waterworks. Handbook of the designer. / Under the general editorship of Dr. tech. sciences, prof. V.P. Nedrigi. - M.: Stroyizdat, 1983, p. 171-173, p. 491.

Claims (1)

A method of erecting horizontal drainage including a receiving, catchment and discharge part, characterized in that all structural parts of the drainage are made of flexible mattresses, consisting of mesh shells and a drainage aggregate, which is made of dense alternating rows of light fascines and perforated pipes wrapped in a geogrid, in this case, the water intake part of the drainage is made of mattresses laid normally to the direction of the filtration flow, the internal drainage part of the drainage is made of mattresses laid in layers and in the direction of the filtration flow, and the outlet part is made of similar mattresses, but arranged in horizontal stripes in a plan and at a certain distance from each other in the direction of the filtration flow, and with a slope from the drainage part to the bottom of the bottom slope, and lightweight fascia of the mattresses is made with a diameter of 15- 20 cm and a length of 2-2.2 m from dry ripened reeds.

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