RU2310708C2 - Device to decrease destructive tsunami action - Google Patents

Abstract

FIELD: structures or apparatus for, or methods of, protecting banks, coasts or harbours.

SUBSTANCE: device comprises shore structure made as embankments and

-shaped tunnels arranged inside the embankments. The tunnels are directed so that inlet and outlet orifices thereof are transversal and face the shore line. Lower tunnel parts have lengths and cross-sectional areas exceeding that of upper tunnel parts. Lower tunnel parts are located at sea level, upper ones project over lower tunnel parts. Tunnels have curvatures providing 180° rotation of velocity vector of liquid stream entering into lower tunnel part as liquid flows via the tunnel to tunnel outlet.

EFFECT: decreased damage caused by tsunami reaching island and continent shore line.

2 cl, 3 dwg, 1 ex

Description

The invention relates to the field of protection of human life and can mainly be used to reduce the destructive effect of the tsunami.

It is well known that the only method of protection against tsunamis at present is to warn the population of an approaching tsunami in order to evacuate people from the zones that it can reach, while the areas themselves affected by the tsunami remain unprotected from its destructive impact.

In the prior art, no sources have been identified that contain information about devices to reduce the destructive effect of the tsunami.

The essence of the invention lies in the development of a device for damping the intensity of a tsunami, i.e. its heights.

The technical result obtained by the implementation of the invention is to reduce the harmful effects resulting from the destructive action of the tsunami when it reaches the coastline of islands and continents.

механической системы равен векторной сумме импульсов всех n материальных точек системыIt is well known that, in accordance with the law of conservation of momentum or momentum, momentum

of a mechanical system is equal to the vector sum of momenta of all n material points of the system

where m _i is the mass of the i-th material point;

- вектор скорости i-ой материальной точки, а также произведению массы m_c всей системы на скорость

ее центра инерции

Поскольку

is the velocity vector of the i-th material point, as well as the product of the mass m _{c of the} entire system by the speed

its center of inertia

Insofar as

- главный вектор всех внешних сил, которые приложены к системе со стороны тел, не входящих в систему (См. Политехнический словарь. (Гл. ред. акад. А.Ю.Ишлинский. - П 50 2-е изд. - М.: Советская Энциклопедия, 1980. - 656 с. илл.), то с уменьшением импульса, что в большей степени происходит при противоположной ориентации векторов

и

масс взаимодействующих систем m_i и m_c, соответственно уменьшается главный вектор сил

, действующих на тела (на береговые сооружения), не входящие в систему.Where

- the main vector of all external forces that are applied to the system by bodies not included in the system (See Polytechnical Dictionary. (Ch. ed. by Acad. A.Yu. Ishlinsky. - P 50 2nd ed. - M .: Soviet Encyclopedia, 1980. - 656 pp. Ill.), Then with a decrease in momentum, which occurs to a greater extent with the opposite orientation of the vectors

and

masses of interacting systems m _i and m _c , respectively, decreases the main vector of forces

acting on bodies (on shore structures) that are not part of the system.

The essential features characterizing the invention.

A device to reduce the destructive effect of the tsunami, including a coastal structure in the form of embankments, inside which tunnels are of ⊃-shape, with inlet and outlet openings oriented perpendicular to the coastline, the length of the lower parts of the tunnels and their cross-sectional area exceeding the corresponding parameters of the upper parts , the lower part of the tunnels is located at sea level, and the upper one rises above it, while the curvature of the shape of the tunnel ensures the rotation of the velocity vector entering its lower Yu portion of the liquid stream at 180 ° outlet flow through the upper part of the tunnel.

The invention is illustrated in the drawing, where figure 1 shows a top view of the device; figure 2 is a section along aa in figure 1; figure 3 is a view of B in figure 2.

The invention is as follows.

входящего в его нижнюю часть потока жидкости от надвигающегося фронта цунами 9 (см. фиг.2) на 180° при выходе потока через верхнюю часть туннеля с вектором скорости

и уменьшение площади поперечного сечения с S₀ до S₁.Near the settlements 1, which can be reached by the tsunami, a coastal structure in the form of embankments 3 is erected along the coastline 2, in which tunnels of the ⊃-shaped form 4 are made (see Figs. 1, 2). Inputs 5 and outputs 6 (see Figs. 1, 2) are oriented perpendicular to the coastline 2. The cross-sectional area of the inputs S ₀ exceeds the corresponding S _{1 of the} upper part (see Fig. 3), while the lower part of the tunnel 7 is located at the level sea, and the top 8 - rises above it (see figure 3). The curvature of the shape of the tunnel provides a rotation of the velocity vector

180 ° entering the lower part of the fluid flow from the impending front of the tsunami 9 (see Fig. 2) when the flow exits through the upper part of the tunnel with the velocity vector

and reducing the cross-sectional area from S ₀ to S ₁ .

The device operates as follows.

When the wave front approaches the coastline, water will first enter the section S _{0 of the} lower part of the tunnel at a speed of υ ₀ . Since the section of the tunnel changes, decreasing towards the exit to S ₁ (S ₁ << S ₀ ), then the water head velocity in the section S ₁ will increase to υ ₁ (υ ₁ >> υ ₀ ). This follows from the fact that the second volume of water passing through any section of the tunnel will be unchanged due to the constant hydrostatic pressure falling on its lower part. Means

Consequently, the flow of water passing through the tunnel will accelerate, at the same time changing its direction by 180 °, and will fall upon the impending crest of the wave (9), thereby reducing its energy. To realize this event, it is necessary to fulfill the geometric dimensions of the tunnel (4) (S ₀ , S ₁ , l ₀ , l ₁ ) such that the water returns from the section S ₁ before the wave crest approaches the upper section of the tunnel.

Such a counter interaction of flows will reduce the tsunami intensity, i.e. will extinguish it, which will achieve the claimed technical result.

Industrial applicability of the claimed device is confirmed by calculations.

At the input, we take a section of the tunnel in the form of a segment (Fig. 1) with a radius R ₀ , at the output, R ₁ , the angle α does not change. The parameters h _i and a _{i are} determined from the relations

where: h _i - the height of the tunnels;

a _i - the width of the holes of the tunnels.

The total length of the tunnel (l ^* ) is defined as

where l ₀ is the length of the rectilinear section of the inlet of the tunnel,

l ₁ - the length of the straight section of the output part of the tunnel.

Let the radius of the segment vary linearly

From the equality of second volumes follows

υS = υ ₀ S ₀ = υ ₁ S ₁ ,

where is the area of the segment

From here

и

при х=l^*, имеем после интегрированияLet τ be the current wave propagation time through the tunnel. Then

and

for x = l ^* , we have after integration

- полное время прохождения воды по туннелю.

- total time of passage of water through the tunnel.

In order to meet the oncoming pressure, it is necessary that

τ ₀ > τ ^* ,

where τ ₀ is the time of approach of the wave to the section II-II,

The greatest effect will be achieved when τ ₀ > (k + 1) τ ^* ,

where kτ ^* is the time during which the water pressure will leave section II-II before meeting the impending wave front, or it is an indicator of the amount of water leaving the section II-II, relative to the volume of water in the tunnel;

k is a coefficient that determines the duration of the oncoming head.

Thus, we obtain

After the transformations we get

Example:

We take R ₀ = 30 m, R ₁ = 15 m, H = 3 m, α = 60 °, l ₁ = 2 m, k = 0.5

Then a ₀ = 30 m, h ₀ = 4 m, a ₁ = 15 m, h ₁ = 2 m, υ ₁ = 4υ ₀

l ₀ > 61 m.

Claims (2)

1. A device to reduce the destructive effect of the tsunami, including a coastal structure in the form of embankments, inside of which tunnels are made

-shaped, inlet and outlet openings oriented perpendicular to the coastline, with the length of the lower parts of the tunnels and their cross-sectional area exceeding the corresponding parameters of the upper parts, the lower part of the tunnels located at sea level and the upper one rising above it, while the curvature of the shape of the tunnel provides rotation of the velocity vector of the fluid flow entering its lower part by 180 ° when the flow exits through the upper part of the tunnel. 2. The device according to claim 1, characterized in that the geometric parameters of the device must correspond to the inequality

where R ₀ , R ₁ - respectively, the radii of the entrance and exit to the tunnel; l ₀ - the length of the rectilinear part of the tunnel at the entrance; l ₁ - the length of the rectilinear part of the tunnel at the exit; H is the height between the top of the lower part and the exit of the upper part of the tunnel; k is a coefficient characterizing the time of water outflow from the outlet of the tunnel to the approach of the wave front.

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