RU2815977C1 - Layered drainage from flexible mattresses - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to hydraulic engineering and can be used as a drainage device of earth dams and embankments on flat and foothill sections of small rivers. In the layered drainage containing flexible mattresses 1 on the lower slope of the earthen structure, flexible mattresses 1 are made of a cylindrical shape from perforated drainage pipes 2, wound around with geomats and a gabion net. Flexible mattresses 1 are laid on downstream slope on top of sand preparation in 5 longitudinal rows in the area of filtration flow outlet so that drainage perforated pipe 2 of one mattress 1 enters pipe 2 of next mattress 1 by 1.0–1.5 cm. Flexible mattresses 1 are laid, starting from the foot of the slope, and are tightly connected to each other by means of metal wire. At the foot of the slope in the base of flexible mattresses 1 there is one longitudinal row of gabion mattresses 6, which are made with length of 2.2–2.5 m, width of 0.8–1.2 m and thickness of 0.4–0.5 m of stone material 7 and galvanized metal mesh. Layered drainage from flexible mattresses can be effectively used on plain and foothill sections of rivers during construction and reconstruction of earthen dams and embankment dams, as well as in hard-to-reach sections of rivers, where delivery of construction equipment is difficult.

EFFECT: invention provides higher efficiency and reduced manufacturing labour input.

1 cl, 5 dwg

Description

The invention relates to hydraulic engineering and can be used as a drainage device for earthen dams and embankment dams on flat and foothill sections of small rivers.

There are known drainages installed on the lower slopes of earth dams,

made of sand, gravel and stone materials [1]. Their main disadvantages are the need for a large amount of stone and sand-gravel material and the complexity of the installation of return filters.

The closest technical solution is layered drainage of earthen structures [2], containing flexible mattresses laid on the lower slope of the earthen structure and made of dense rows of light fascines and mesh shells. At the same time, flexible drainage mattresses on the lower slope are made of pre-prepared gabion mattresses of prefabricated construction, 1-1.5 m wide, 0.4-0.6 m thick and up to 2.5 m long. Along the upper row of mattresses with recess in the lower slope The slope is covered with heavy mattresses made from bags of local and plant soil. Flexible and gabion mattresses are mainly made of lightweight fascines made from dry reeds. The main disadvantages of this technical solution are the complexity of the design and the use of reeds for the manufacture of lightweight fascines, which have a limited service life and cannot be found everywhere. In addition, with possible erosion of the channel at the base of the downstream slope, there is a high probability of destruction of the drainage.

The purpose of the invention is to increase operating efficiency and reduce the labor intensity of manufacturing.

This goal is achieved by the fact that in a layered drainage containing flexible mattresses on the downstream slope of an earthen structure, the flexible mattresses are made of a cylindrical shape from perforated drainage pipes wrapped around geomats and gabion mesh, flexible mattresses are laid on the downstream slope on top of the sand preparation in longitudinal rows in the exit area filtration flow, so that the drainage perforated pipe of one mattress enters the pipe of the next mattress by 1-1.5 cm, while they are laid, starting from the bottom of the slope, tightly connected to each other using metal wire, and at the bottom of the slope at the base of flexible mattresses There is one longitudinal row of gabion mattresses, which are made 2.2-2.5 m long, 0.8 - 1.2 m wide and 0.4-0.5 m thick from stone material and galvanized metal mesh.

In figure 1. shows a cross-section of an earthen structure (dam or dike) with layered drainage; figure 2 - plan of a fragment of drainage, figure 3 - flexible mattress; figure 4 - geomat; Fig. 5 - gabion mattress.

Layered drainage consists of flexible mattresses 1, made of perforated pipes 2, geomat 3 and gabion mesh 4, wrapped in layers around pipe 2, which form the water receiving (drainage) part of the mattress 1. The flexible mattresses are laid in dense rows on sand preparation 5, located on the downstream slope, starting from its base, to a level above the exit of the filtration flow into the tailwater (LB). At the bottom of the slope at the base of the first row of mattresses 1 along the riverbed (with recess into the bottom) there is a longitudinal row of gabion mattresses 6 made of stone aggregate 7 (sorted gravel and pebbles) and galvanized metal mesh 8.

Layered drainage from flexible mattresses is constructed as follows.

All elements of layered drainage are made manually at the installation site with partial use of mechanical devices. First, to produce flexible mattresses 1, geomat 3, gabion mesh 4 and perforated drainage pipes 2 are prepared (brought) in advance in the required volume. Next, gabion (galvanized metal) meshes 4 and 8 are cut to the size of flexible and gabion mattresses 1 and 6 in the required quantity. perforated polymer pipes 2 (diameter 30 - 40 mm), as well as stone material 7 in the required volume. From these materials, flexible mattresses 1 are prepared in the required quantities. And gabion mattresses 6 are made on site with a length of 2.2-2.5 m, a width of 0.8 - 1.2 m and a thickness of 0.4-0.5 m. Accepted the dimensions of gabion mattresses are the most acceptable from the point of view of ensuring the stability of the earthen structure and the manufacturability of drainage construction.

Construction is carried out in sections, and the number of sections can be one, two or more. First, construction is carried out on the first site; for this purpose, a trench is developed at the bottom of the slope and along the riverbed, 1.5 m wide and up to 1.0 m deep. After which the installation of gabion mattresses 6 from galvanized metal mesh 8 and stone aggregate 7 (from sorted gravel and pebbles) begins. Then, upon completion of the installation of gabion mattresses 6, sand preparation 5 (15-20 cm thick) is arranged above them on the lower slope (15-20 cm thick), to a level above the outlet of the filtration flow in the NB. On top of the sand preparation 5 (over the entire area to a level above the exit of the depression curve), flexible mattresses 1 are laid in dense rows, so that the perforated drainage pipe 2 of one mattress enters 1.0 - 1.5 cm into the pipe of the subsequent mattress 1. In addition, between each other flexible mattresses 1 are connected (tied) using metal wire.

In the same way, flexible and gabion mattresses for layered drainage are built in the second and subsequent sections.

Layered drainage from flexible mattresses works as follows.

Filtration water, moving under the influence of hydrostatic pressure from the upstream side (UP) through the pores of the soil of the dam or dam body, enters the zone of the water intake part of the layered drainage (where the sand preparation is 5). Next, through the sand preparation 5, geomats 3 freely accept water due to their high water permeability and pass through slotted holes into drainage pipes 2, which are transported further and discharged into the NB. The presence of water in the NB does not interfere with the operation of the drainage; only the water level in the downstream (UNB) should be significantly lower than the level of the filtration flow exiting the downstream slope. Therefore, the drainage of the proposed design is recommended for use in medium and low-pressure soil dams and embankment dams, and with insignificant water depth in the NB, which cannot influence the operating mode of the drainage. The efficiency of layered drainage is increased due to the presence of a buried row of gabion mattresses 6 (at the base of the first row of flexible mattresses 1 and the river bed), which prevents possible undermining of the bed and destruction of the drainage.

When making drainage, the main filtration material is geomat - a fairly stable and durable artificial material that works effectively in an aquatic environment and is a highly draining material. This eliminates the removal and penetration of small soil particles into water intake pipes 2. As a result, the safe reception and removal of filtered water through the body of earthen structures is ensured at all possible operational water levels in the WB.

Layered drainage made from flexible mattresses can operate effectively without major repairs for 20 years or more. Due to the fact that geomat is a highly draining and fairly resistant material that can last in an aquatic environment for 20 years or more. The use of geomats ensures not only water permeability and design flexibility, but also helps retain moisture in the body of the structure for a long time. This creates good conditions for the germination of grasses and shrubs on the lower slope of the earthen structure. Over time, the lower slope will be completely overgrown with grass and shrubs, and after a few years it will turn into a continuous turf, with plant branches growing upward and roots downward and in breadth.

Thus, the layered drainage of the proposed design does not create interference and will help the development of nature and be included in the ecosystem of the territory.

Layered drainage from flexible mattresses can be effectively used on flat and foothill sections of rivers during the construction and reconstruction of earthen dams and embankment dams. And also in hard-to-reach areas of rivers, where earthworks are being built and the delivery of construction equipment is difficult.

A source of information

1. Hydraulic structures. Designer's Handbook. / Under the general editorship of Dr. Tech. sciences, prof. V.P. Nedrigi. - M.: Stroyizdat, 1983, p. 172-173, p. 491.

2. Layered drainage of earthen structures. RF Patent No. 2614071 E02B 3/12, 2017, bulletin. No. 9. / Kurbanov S.O., Dudarova F.T.

Claims (1)

Layered drainage containing flexible mattresses on the downstream slope of an earthen structure, characterized in that the flexible mattresses are made of a cylindrical shape from perforated drainage pipes wrapped around geomats and gabion mesh, flexible mattresses are laid on the downstream slope on top of the sand preparation in longitudinal rows in the area where the filtration flow exits, so that the drainage perforated pipe of one mattress enters the pipe of the next mattress by 1.0-1.5 cm, while the flexible mattresses are laid starting from the bottom of the slope and tightly connected to each other using metal wire, and at the bottom of the slope at the base of the flexible mattresses there is one longitudinal row of gabion mattresses, which are made 2.2-2.5 m long, 0.8-1.2 m wide and 0.4-0.5 m thick from stone material and galvanized metal mesh.