RU2528491C2 - Arrangement of vertical wells for trapping contaminant flows from accumulators - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to protection of ground waters from contaminants and can be used for trapping of contaminated flows from accumulators to exposed waterways. Proposed method consists in construction of several trapping wells drilled at a distance from end sections of accumulator directed towards ground flow, that is, at outlet of maximum filtrate volume in zone of higher output gradients of the head. Set of wells is arranged with increase in diameter and depth from well set edges to the centre. Pit in plan on terrain features minimum width, pit length being directed towards ground flow.

EFFECT: efficient trapping and diversion of more concentrated filtrate.

2 cl, 7 dwg

Description

The invention relates to the field of protection of groundwater from contaminated filtrates from reservoirs and can be used to intercept polluted streams from reservoirs on the way to open streams.

A known method of constructing a linear series of perfect wells located near a circuit with constant pressure / Emelyanov A.V., Kleiman D.B., Stanchenko I.K., Cheltsov M.I. Water reduction in construction // Ed. Construction, M., 1971, p. 86-92. This method provides for the location near the power circuit of a linear water-lowering plant in the form of injector needle filters.

The disadvantage of this method is the device of wells of the same length and diameter along the contour of the pressure source, which requires additional costs.

The results of studies on filtering from storage media by the analytical method are known / Romanov A.V., Selyuk E.M. Analytical methods for predicting the filtration of industrial effluents from sludge storages and storage tanks. // Issues of filtration calculations of hydraulic structures. Sat No. 5. Ed. lit. by building. M., 1973, p. 78-95.

The disadvantage of the above studies is that horizontal drainage is used to intercept the contaminated filtrate from sludge storages and storage tanks, which does not take into account the form of the filtrate distribution in the soil, not in width, not in length.

The closest technical solution is a method of protection against soil flow pollution, including the construction of a number of intercepting vertical wells / Kosichenko Yu.M., Abukhanov A.Z., Ishenko A.V., Omelaev T.Yu. The study of an effective option for protection against soil pollution by ash and slag waste of Novocherkasskaya TPP // News of universities. North - The Caucasus. Region. Engineering, 2001, No. 2. p. 96-100. This method involves the installation of a number of vertical wells of the same diameter and length and completely overlapping the entire contaminated stream along the dividing line of clean and contaminated flows.

The disadvantage of these methods is the device of a number of vertical wells of the same diameter and length, which requires additional costs.

The technical result, the invention is aimed at, is that the proposed method for placing vertical wells to intercept a contaminated stream from reservoirs is more effective, since by reducing the width of the pit and orienting the length with the direction of the ground stream, the spreading area of the contaminated filtrate is reduced, which gives the ability to reduce the number of vertical intercepting wells. In addition, by increasing the diameter and depth of the wells to the center of a number of intercepting wells, effective interception and removal of the most concentrated filtrate is ensured.

Similar studies as an example were performed by modeling the interception of the filtration stream of polluted water from the pit for the accumulation of ash and slag pulp in an electrohydrodynamic installation (EGDA) for the II section of the ash dump of Novocherkasskaya state district power station. / Improving the engineering protection of groundwater from pollution by filtrate of industrial waste storage devices: abstract of Cand. those. Sciences: 05.23.07 // Sklyarenko E.O. - Novocherkassk, 2008 .-- 23 p.

During the simulation, the following assumptions were made: the embankment height was 20.0 m, the pit area was 20.4 ha, the soil on the route was assumed to be uniform, the pit model was made of a thin copper plate, the slope of the terrain was i = 0.001. Taking into account the slope of the terrain and the accepted scale, the boundary potentials of the voltage Ш ₁ -100% and the bus Ш ₂ -0% were established at the edges of the experimental model of the foundation pit from conductive paper.

As a result of the simulation, a general scheme was obtained for the interaction of clean soil flow and contaminated filtrate from the ash dump (Fig. 1). When constructing the hydrodynamic grid, the section point “A” and the line of separation of the soil flow and the contaminated filtrate were established.

Analysis of the distribution of pressure gradients (figure 2) along the length of the "plume" of the distribution of the filtrate from the ash dump into groundwater showed the following:

1. If we conditionally divide the area of the pit into zones (for example, zones I, II, III, IV), then the pressure gradients j _{output will be} distributed as follows (see figure 2). In zone IV, the output gradients will be maximum and amount to 45.9% of the 100% distribution of the pressure gradients in the zones.

2. If we take the output pressure gradients of the IV zone as 100%, then Fig.2 shows that the pressure gradients in the III zone are 53.85% of the IV zone, in the second zone 46.1% and in the I zone - 17.7 %

3. From figure 2 it is seen that the pressure gradients J _in increase, starting from I to IV zone of the pit, in the IV zone they are 5.6 times higher than in the I zone.

From the obtained results of experimental studies, the following practical conclusions can be drawn:

- to shield the storage bed, arrange anti-filtration curtains, protective drains, intercepting vertical wells for reverse water supply, it is most expedient within the IV zone of the pit (Fig. 2), since the highest output pressure gradients are identified in this zone and, accordingly, it can be assumed that the highest the percentage removal of contaminated filtrate.

According to the conditions for constructing a hydrodynamic grid, all costs of individual tapes are equal to each other:

Δq = Δw

where Δw is the area of the curved square of the hydrodynamic grid;

v is the filtration rate.

However, the area Δw of the curved square of the hydrodynamic grid is different; therefore, one flow rate of the contaminated filtrate, but with a different concentration, is passed through this area.

Having analyzed the concentration of the contaminated filtrate and the filtration rate in a series of wells along the hydrodynamic grid, it was found that the highest value of the filtrate concentration c and the filtration rate v will be in the center of the row (Fig. 3).

To align the graph, it is necessary to bore the diameter of the wells d and the depth h with a gradual increase towards the middle of the flow and take the maximum in the center of a number of wells (4, 5).

The maximum value of the output pressure gradients along the width of the filtration stream (see horizontal scale) and along the propagation length of the contaminated filtration stream (see vertical scale) is in the center of the stream (Fig.6).

A similar pattern of the distribution of pressure gradients over each row in width and along the length of the flow in the propagation dynamics (Fig. 7).

The constructed hydrodynamic grid allows you to determine all the flow elements of interest.

The gradient is considered equal to the ratio:

,

,

where Δφ is the potential difference between the potentials between the equipotential line φ = const and the neighboring equipotential line φ + Δφ = const;

Δs are the distances along the streamline between the two given equipotentials.

Claims (2)

1. A method of arranging vertical wells for intercepting a contaminated stream from reservoirs, comprising a series of intercepting wells, characterized in that the vertical wells are arranged at a distance from the end part of the reservoir oriented toward the ground flow, i.e. in the area of the output of the maximum volume of the filtrate in the zone of the highest output pressure gradients, while a number of wells are arranged with increasing diameter and depth from the edges of a number of wells to the center. 2. The method according to claim 1, characterized in that the pit in the plan on the ground is placed minimal in width, orienting the length of the pit in the direction of movement of the soil stream.

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