RU2465395C1 - Dam from soil materials - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: dam comprises an anti-filtration element in the form of a core from clayey soil, upper and lower side prisms from large fragmental soils, a head wall from non-heaving soil and a road surface on a dam crest traffic area. The material of at least the road surface has a coefficient of solar radiation absorption of at least 0.9. The road surface of the dam crest traffic area is made from asphaltic concrete.

EFFECT: higher reliability of a dam due to prevention of freezing of its core upper part.

5 cl, 1 dwg

Description

The invention relates to hydraulic engineering and can be used in the construction and operation of dams of soil materials in the northern climatic zone.

It is a well-known dam made of soil materials, which contains an anti-filtration element in the form of a core made of clay soil, upper and lower side prisms from coarse soil, a head made of non-porous soil (the same: a protective layer) and road surface of the carriageway of the dam crest [1].

The disadvantage of such a dam is its lack of reliability in the northern building and climatic zone. At negative average annual outdoor temperatures in the area in the upper part of the core, permafrost can develop, often with a layered texture. So, the upper parts of the core dams built in the northern climatic zone are already frozen up to 8 m or more, i.e. significantly lower than the NPU, with the formation in the upper part of the core of the frozen "overlap", supported by weakly deformed lateral prisms of the dam. All this leads to the formation of cracks and unconsolidated zones in this part of the dam core [2].

The main structural and technological features of well-known technical solutions (both implemented and unrealized), aimed at eliminating the indicated drawback of a well-known dam, are as follows [3]:

- the height of the tip (protective layer) is sufficient to prevent freezing of the core from above (economically justified at an average annual outdoor temperature of at least minus 2-3 ° C);

- the core above the NPU is made of weakly grained frozen soil;

- the tip of the dam contains a rigid or flexible impervious diaphragm;

- the upper part of the core is equipped with a film that prevents the migration of water from below into the freezing head;

- the upper part of the core is heated by water or electric current;

- the upper part of the core contains a trench filled with loose or clogging material;

- the core above the NPU is created by filling in a trench with cohesive soil made in the tip;

- the upper part of the core contains a trench filled with a refractory gel-like material - a cryophylactic with a low freezing temperature [4];

- in the head above the core, a repair and inspection heated gallery was made [5].

A common drawback of these well-known technical solutions (means) is that, firstly, their implementation on an existing dam is associated with complex and costly reconstruction of the dam head, and secondly, at an average annual outdoor temperature below minus 7 ° C the operability of a dam with a reconstructed head may be insufficient (except for the last most expensive head [5]). However, the possibility of a combination of two or more of these technical solutions in one dam is not visible.

The problem to which the invention is directed, is to increase the reliability of the dam and save money on its construction and operation in the northern climatic zone by simplifying and cheapening the work aimed at preventing freezing of the upper part of the dam core, as well as due to the ability of the proposed technical means to work together with well-known technical solutions.

The problem is solved in that a dam of soil materials containing an anti-filter element in the form of a core of clay soil, upper and lower side prisms of coarse soil, a head of non-porous soil and a road surface of the carriageway of the dam crest, according to the invention, at least a road material Covering the carriageway of the dam crest has a absorption coefficient of solar radiation of at least 0.9.

Additionally:

- the impassable part of the dam crest contains a thin layer coating that increases the absorption coefficient of solar radiation on the impassable part of the dam crest to a value of at least 0.7;

- the dam contains a thin layer coating that is located on the slope of the dam from the crest to a predetermined level and increases the absorption coefficient of solar radiation on the slope to a value of not less than 0.7;

- the road surface of the carriageway of the dam crest is made of asphalt concrete;

- a thin coating is made of bituminous or paint material of a dark color.

It is the fact that, according to the indicated rules, giving the outer surface of the upper part of the dam an increased, against the usual, ability to absorb solar radiation provides increased heating of the upper part of the dam. This circumstance, with the corresponding economically feasible head height, due to the increased heat supply and the heating effect of filtering water through the dam, can prevent the freezing of the upper part of the core in the cold season at an average annual outdoor temperature of about -6-7 ° C on the ground.

The drawing, as an example, schematically shows the upper part of the dam in cross section.

The dam from soil materials contains a core 1 of clay soil, side prisms, top 2 and bottom 3, from stone sketches, transition layers, top 4 and 5 and bottom 6 and 7, head 8 made of gravel sand and road surface 9 of the carriageway of ridge 10 dams. The road surface 9 is made of asphalt concrete, which has a solar radiation absorption coefficient of at least 0.9. The shoulders 11 form an impassable part on the ridge 10 and comprise a thin layer coating 12 which is made of bituminous or paint material of dark color and which increases the absorption coefficient of solar radiation on the shoulder 11, at least to a value of at least 0.7.

In the depicted example, the sun's rays 13 are directed mainly to the lower slope 14 of the dam, which is a favorable condition for using the present invention. In this case, it is advisable to place a thin-layer coating 12 (bitumen, dark-colored paint material) on the downstream slope 14, which on the slope 14 will also increase the absorption coefficient of solar radiation, at least to a value of at least 0.7. A thin-layer coating 12 on the slope 14 is located from the crest 10 of the dam to the level 15 set on the slope 14, for example, to point A — the level of depression in the curve of depression 16 when the water is downstream.

The essence of the thermotechnical calculations of the dam for specific climatic conditions, its location and orientation relative to the cardinal points is that first they predict the freezing border 17 of the upper part in the prototype dam, and then the freezing border 18 in the proposed dam. Then evaluate the effectiveness of the last dam.

In case of insufficient efficiency, the possibility of supplementing the dam with a known technical solution that is structurally compatible with the proposed dam is considered.

The peculiarity of the construction of the dam is that when creating a thin-layer coating 12, the material on the surface of the shoulder 11 and the slope 14 is advisable to apply with a spray. The direction of the spray nozzle should be directed from South to North, i.e. in the prevailing direction of sunlight 13.

The peculiarity of the operation of this dam in specific climatic conditions is as follows.

The abundant absorption of solar radiation heat by the upper part of the dam and its accumulation mainly during the warm period of the year prevents the freezing of the upper part of core 1 during the cold season at an average annual outdoor temperature in the area of about minus 6-7 ° C. This is about 3-4 ° C lower than in a conventional dam prototype, in which the height H _og tip 8, which protects the core from freezing 1 is adopted in accordance with the heat engineering calculation and economic feasibility.

The amount of solar radiation depends on the height of the sun, which determines the distance that a sunbeam must travel before it reaches the surface of the earth, season, transparency of the atmosphere (dust, water vapor, ozone, atmospheric pressure, etc.). Solar radiation is usually measured by its thermal effect (actinometers, pyrheliometers) and is expressed in calories per surface unit per unit time. Solar radiation is not blocked by clouds and it is strong near the poles during the polar days when the sun is even above mid-horizon at midnight. At the equator, there is practically no difference between winter and summer.

The intensity of absorption by the upper part of the dam of heat of solar radiation depends on the intensity of the sun's beam 13 on the ground, the angle of its incidence on the outer surface of the dam and the absorption coefficient of the material of this surface.

The absorption coefficient of solar radiation depends on the color of the surface and varies from 0.25 white glossy surface (enamel) to 0.9 black surface (asphalt concrete). Moreover, the most common rock formations have an absorption coefficient of about 0.6 or less, namely light gray sandstone 0.62, granite 0.55, dark limestone 0.5 and light limestone 0.35.

With regard to the dams of the Kureyskaya hydroelectric station located in operation beyond the Arctic Circle, the use of the present invention can be as follows. Covering the carriageway of the dam crest is made of asphalt concrete, and a thin-layer coating of the roadway and slopes of the upper part of the dam from liquid material prepared on site. This material may consist of substandard graphite and / or coal present in the dumps at the hydroelectric power station, mixed after grinding with a liquid binder. Such a layer will provide a value of the absorption coefficient of solar radiation by the outer surface of the dam of about 0.8.

Designations

1 - core

2 - riding side prism

3 - bottom side prism

4 and 5 - upper transitional layers

6 and 7 - lower transitional layers

8 - tip

9 - road surface

10 - crest (dam)

11 - roadside (impassable part)

12 - thin coating

13 - sunbeam

14 - slope

15 - level of point A

16 - depression curve

17 - freezing boundary in the dam-prototype

18 - freezing boundary in the proposed dam.

A is the point of suction

H _og - the height of the tip.

Information sources

1. SNIP 2.06.05-84 * Dams from soil materials, paragraphs 2.1 *, 2.14, 2.15.

2. Yagin V.P. Dams of soil materials erected in the northern climatic zone. // Hydrotechnical construction, 1997, No. 3.

3. Yagin V.P. The head of the soil dam being erected in the northern climatic zone. // Hydrotechnical construction, 2002, No. 4.

4. Pat. Russian Federation No. 2418132, publ. 05/10/2011.

5. Pat. Russian Federation No. 2207428, publ. 06/27/2003.

Claims (5)

1. A dam of soil materials containing an anti-filter element in the form of a core of clay soil, upper and lower side prisms from coarse soil, a head made of non-porous soil and a road surface of the carriageway of the dam crest, characterized in that the material is at least of a road surface The carriageway of the dam crest has a solar radiation absorption coefficient of at least 0.9. 2. The dam according to claim 1, characterized in that the impassable part of the dam crest contains a thin layer coating, which increases the absorption coefficient of solar radiation on the impassable part of the dam crest to a value of at least 0.7. 3. The dam according to claim 1, characterized in that it contains a thin layer coating that is located on the slope of the dam from the crest to a predetermined level and increases the absorption coefficient of solar radiation on the slope to a value of not less than 0.7. 4. The dam according to claim 1, characterized in that the road surface of the carriageway of the dam crest is made of asphalt concrete. 5. The dam according to claim 2 or 3, characterized in that the thin-layer coating is made of bitumen or paint material of a dark color.

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