RU2569965C1 - Method to develop cutoff curtain - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method includes erection of a water retaining earth dam 7, placement of a layer of geotextile needle-punched non-woven material 4 from synthetic fibres with volume density of 100-150 kg/m³ and treatment of dam slope with a water soluble powder polymer. After placement of the geotextile material 4 layer it is treated at negative temperature of ambient air by aqueous solution of polyvinyl alcohol and boron compound, for instance, borax or boric acid, with flow rate of 5-10 l/m² at their concentration of 3.0…12.0%, 0.2…1.0% accordingly. Then after freezing of the applied solution the geotextile needle-punched non-woven material 4 is covered with a soil layer 3.

EFFECT: increased reliability of hydraulic insulation of a cutoff curtain under impact of sign-alternating temperatures due to generation of a layer of cryogel composite by a freezing-thawing process, strength and antifiltration properties of which are not deteriorated under multiple impact of freezing-thawing processes.

1 dwg

Description

The invention relates to hydraulic engineering, and in particular to methods of creating impervious curtains in hydraulic structures in the northern climatic zone (SCKZ).

There is a method of creating anti-filter curtains by erecting a water-bearing earthen dam and placing a layer of polyethylene or polyvinyl chloride geomembranes on slopes (O.Yu. Lupachev, V.I. Teleshev. Antifiltration elements from geomembranes. Application experience in hydraulic engineering. Civil Engineering Journal No. 6, 2009, p. 35-43.)

The disadvantage of this method is the low reliability of the air curtain, associated with possible damage to the geomembranes under mechanical or thermal influences, especially frequent in the SCKZ, as well as vulnerability to filter the joints of the panels.

A known method of creating anti-filter curtains, including erecting a water-resistant earthen dam and treating the wet slope of the dam with a water-soluble powder polymer, before applying the polymer on the slope, place a layer of geotextile material, and after applying the polymer, the slope is irrigated with water and covered with a layer of soil treated with a water-soluble powder polymer with a flow rate of 0 5 ... 2.0 kg / m ² , then the slope is treated alternately with aqueous solutions of sodium carboxyl methyl cellulose and ferric chloride at a concentration of 0.5-2 , 0% with a flow rate of 5-10 l / m ² , needle-punched non-woven material from synthetic fibers with a bulk density of 100-150 kg / m ^{3 is} used as geotextile material (RF patent No. 2310711, IPC E02B 3/16, publ. 20.11.2007 g.).

According to the greatest number of similar features and the result achieved when using this technical solution is selected as a prototype.

The disadvantages of the prototype are that when exposed to alternating temperatures, the filtering strength of the curtain is lost, this also applies to the joints of the panels and the adhesion of the panels to the underlying slope of the earthen dam. The highly concentrated thixotropic system formed in this method, which is not prone to leaching, containing a significant number of gel particles, after a freezing process that destroys the coagulation structure, during the thawing process is unable to return the coagulation structure under the influence of hydrostatic pressure pressure, thereby the coagulation structure under the influence of pressure of ever-increasing free water erupts in one place, forming a linear erosion.

The technical result of the invention is to increase the reliability of waterproofing of air curtains when exposed to alternating temperatures.

To achieve the specified technical result in the method of creating anti-filter curtains, including the construction of a water-resistant earthen dam, placing a layer of geotextile needle-punched non-woven material from synthetic fibers with a bulk density of 100-150 kg / m ³ and processing the slope of the dam with a water-soluble powder polymer, after placing a layer of geotextile needle-punched non-woven material , it is treated at a negative ambient temperature with an aqueous solution of PVA polyvinyl alcohol and neniya boron, for example boric acid or borax, at a rate of 5-10 l / m ² at concentrations of 3.0 ... 12.0%, 0.2 ... 1.0%, respectively, then after freezing the applied solution needlepunched nonwoven geotextile material is coated a layer of soil.

The distinguishing features of the proposed method are the placement of a layer of geotextile needle-punched non-woven material, processing of a geotextile needle-punched non-woven material, at negative ambient temperature, with an aqueous solution of PVA and boron compound, coating the geotextile needle-punched non-woven material with a soil layer after freezing the applied solution.

Due to these signs, the use of the PVA in the proposed method is determined by its properties: hardening the soil both in the frozen state and during thawing, as well as when exposed to alternating temperatures, in addition, the PVA is non-toxic and does not pose a threat to the environment. The amount of PVA with a concentration of less than 3% does not provide waterproofness and stability of the waterproofing coating. The PVA content in the solution with a concentration of more than 12% makes it difficult to impregnate the geomaterial and penetrate the solution into the underlying soil. The penetration of the solution into the protective sand layer provides a more reliable connection between the geomaterial and the underlying protective layer. The consumption of an aqueous solution of PVA 5-10 l / m ^{2 is} sufficient for complete impregnation of the geomaterial and for some penetration into the underlying protective sand layer. The penetration depth of an aqueous solution for a flow rate of 5-10 l / m ² can reach several cm and is determined by the viscosity of the PVA solution and the filtering ability of the protective sand layer.

The proposed method is illustrated in the drawing, which shows the device of the air curtain.

The drawing shows a reservoir 1, a mounting of a slope 2, a soil layer 3, a geotextile needle-punched non-woven material 4, impregnated with an aqueous solution and a solution of a compound of boron, a zone of penetration of 5 solution into a protective permeable sand layer 6, a water-resistant earthen or rock-fill dam 7.

The method is as follows.

A water-resistant earthen or rock-fill dam 7 with a protective permeable sand layer 6, on which a layer of geotextile needle-punched non-woven material 4 made of synthetic fibers with a bulk density of 100 ... 150 kg / m ³ having high strength and homogeneous finely porous structure. At negative ambient temperatures, a layer of geotextile needle-punched non-woven material 4 is treated by sprinkling or irrigation with an aqueous PVA solution at a rate of 5-10 l / m ² at their concentration: polyvinyl alcohol - 3.0 ... 12.0, boron compounds: borax or boric acid - 0.2 ... 1.0. An aqueous solution of PVA is formed by dissolving boron compounds in water: borax or boric acid - 0.2-1.0, it is also possible to use phosphoric acid, iron and chromium compounds, including ferric chloride, chromates and dichromates, i.e. all those substances which, when reacted with polyvinyl alcohol, form water-insoluble complex compounds with it, then dissolve with stirring PVA powder by heating to 50 ° C - 90 ° C, the water temperature is determined by the brand of PVA used. Then, after freezing the applied solution in the penetration zone 5, the geotextile needle-punched nonwoven material 4 is covered with a layer of soil 3 and the fastening of the upper slope 2 from coarse material from erosion by the reservoir 1.

Improving the reliability of the waterproofing of the air curtain created by the proposed method, when exposed to alternating temperatures, is ensured by the formation of a cryogel composite layer by the freezing-thawing process, the strength and antifiltration properties of which do not deteriorate after repeated exposure to freezing-thawing processes. Improving the reliability of the air curtain is also provided by strengthening the connection of the geomaterial and the underlying layer due to the strengthening effect of PVA on the soil material.

Claims (1)

A method of creating an airtight curtain, including the construction of a water-resistant earthen dam, placing a layer of geotextile needle-punched non-woven material from synthetic fibers with a bulk density of 100-150 kg / m ³ and treating the slope of the dam with a water-soluble powder polymer, characterized in that it is treated with a negative layer of geotextile material ambient temperature with an aqueous solution of PVA polyvinyl alcohol and boron compounds, such as borax or boric acid, with a flow rate of 5-1 0 l / m ² at a concentration of 3.0 ... 12.0%, 0.2 ... 1.0%, respectively, then after freezing the applied solution, a geotextile needle-punched non-woven material is covered with a layer of soil.