Protection Structure and Method for Laying Geomembrane on Steep Slope in Tailings Pond Area

Abstract

The present invention discloses a protection structure and method for laying geomembrane on a steep slope in a tailings reservoir area, belonging to the field of environmental engineering, and solves the problems of easy aging of geotextiles and short protection time existing in the existing methods. In the present invention, a cushion layer and a geomembrane are sequentially laid on the surface layer of the foundation, a three-dimensional drainage net sheet is laid on the surface layer of the geomembrane, a plurality of irregular holes are arranged on the surface and inside of the three-dimensional drainage net sheet, and the pores of the three-dimensional drainage net sheet are filled with sandy soil. The method of the present invention: level the foundation, lay a cushion layer on the surface layer of the foundation; lay a geomembrane on the cushion layer; lay a three-dimensional drainage net sheet on the geomembrane, and fill sandy soil in the pores of the three-dimensional drainage net sheet. The present invention can effectively prevent the problems of sandy soil sliding or geomembrane deformation, and avoid the geomembrane being exposed to the air and exposed to wind and sun; after the three-dimensional drainage net sheet is filled with sandy soil, it has the function of drainage and seepage, can resist the scouring effect of rainwater, and effectively reduces the phreatic line of the tailings dam.

Description

Technical Field

[0001] The present invention belongs to the field of environmental engineering, and particularly relates to a protection structure and method for laying geomembrane on a steep slope in a tailings pond area. Background Art

[0002] As a polymer matrix material, geosynthetics have been widely used in civil engineering such as water conservancy, municipal engineering, architecture, transportation, subway, and tunnel in recent years. Geomembrane is a kind of anti-seepage geosynthetic material with extremely strong water impermeability and relatively high physical and mechanical property indexes such as tensile strength, tear resistance, and puncture resistance. It is mainly used in anti-seepage projects for the safe treatment of materials such as tailings, various waste liquids, and garbage. For small-area laying of geomembrane, it can generally be covered by tailings in 1 - 2 years, and the aging problem of geomembrane is not yet prominent. However, after large-area laying of geomembrane, it will be covered by tailings only after about 8 - 10 years. The geomembrane is easily affected by external forces and factors such as oxygen, light, and heat in the environment when exposed to the air for a long time, and undergoes degradation and other reactions, resulting in the aging of the geomembrane, loss or partial loss of properties such as strength, and even damage and loss of anti-seepage function. Therefore, it is very necessary to invent a method for protecting geomembrane.

[0003] Existing geomembrane protection methods include spraying concrete on the surface of the geomembrane and setting a machine-woven mesh between the initial spraying of concrete and the re-spraying of concrete, which is for the facing composite geomembrane and mainly considers the reduction effect of water level rise and fall on the performance of the composite geomembrane; there is a protection structure for the geomembrane anti-seepage layer in artificial wetlands, which mainly considers the damage caused by foundation settlement or bottom gas expansion to the geomembrane; there is also a protection method during the construction process of laying geomembrane under dynamic load. Since the area of the tailings pond area is large and some slopes are steep, the cost of spraying concrete is high and the construction difficulty is great. Therefore, the existing relevant literatures are not suitable for use in the anti-seepage project of the tailings pond.

[0004] In the anti-seepage project of the tailings pond, the traditional method is to lay a layer of geotextile on the geomembrane to protect the geomembrane. However, the geotextile will also age and lose its protection function after being in the air for too long. The protection time of the geotextile generally does not exceed 1 year, or when encountering strong wind and bad weather, the geomembrane will be rolled up or even torn.

[0005] In the tailings pond project, it is necessary to lay a large-area geomembrane anti-seepage layer. Since the production tailings discharge cycle of the concentrator is generally long, the geomembrane will be exposed to the air for a long time after being laid. Even if it is laid in phases, some of the early geomembranes will also be exposed to the air for 4 - 5 years. It is far from enough to rely solely on a layer of geotextile for protection. The area of the tailings pond area is large and some slopes are steep. It is easy for other protection measures to slide and cannot be fixed. Summary of the Invention

[0006] The purpose of the present invention is to provide a protection structure for laying geomembranes on steep slopes in the tailings reservoir area, so as to solve the problems of easy aging of geotextiles and short protection time existing in the existing methods.

[0007] Another purpose of the present invention is to provide a protection method for laying geomembranes on steep slopes in the tailings reservoir area.

[0008] The technical solution of the present invention is: a protection structure for laying geomembranes on steep slopes in the tailings reservoir area, in which a cushion layer and a geomembrane are sequentially laid on the surface layer of the foundation, and a three-dimensional drainage net sheet is laid on the surface layer of the geomembrane. There are multiple irregular holes on the surface and inside of the three-dimensional drainage net sheet, and the pores of the three-dimensional drainage net sheet are filled with sandy soil.

[0009] As a further improvement of the present invention, the aperture of the irregular holes is 10 mm - 30 mm.

[0010] As a further improvement of the present invention, the opening density of the irregular holes is 15% - 20%.

[0011] As a further improvement of the present invention, the thickness of the three-dimensional drainage net sheet is 100 mm - 200 mm. If the three-dimensional drainage net sheet is too thin, it is not conducive to stabilizing the sandy soil; considering its stability and economy, the thickness is preferably 100 mm - 200 mm.

[0012] As a further improvement of the present invention, the particle size of the sandy soil is 0.5 mm - 10 mm. If the particle size of the sandy soil is too small, it is easily blown away by the wind; after the tailings are covered later, under the pressure of the tailings, in order to prevent the sandy soil from piercing the geomembrane, the particle size of the sandy soil should not be too large.

[0013] As a further improvement of the present invention, the cushion layer adopts a bentonite blanket, which has waterproofness and high ductility, and the specification is selected as 4000 g / m 2 -6000 g / m 2 . The cushion layer prevents the geomembrane from being pierced by stones.

[0014] As a further improvement of the present invention, the thickness of the geomembrane is 1.5 mm - 3.0 mm.

[0015] As a further improvement of the present invention, the slope of the reservoir area is greater than 1:3.0.

[0016] A protection method for laying geomembranes on steep slopes in the tailings reservoir area includes the following steps:

[0017] A. Remove the humus soil and irregular sharp stones on the surface layer of the reservoir area, level the foundation, and then lay a cushion layer on the surface layer of the foundation;

[0018] B. Lay a geomembrane anti-seepage layer on the laid cushion layer and anchor it well;

[0019] C. Lay a three-dimensional drainage net sheet on the laid geomembrane, and then fill the pores of the three-dimensional drainage net sheet with sandy soil.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. In the present invention, a three-dimensional drainage net sheet is laid on the upper surface of the laid geomembrane, and sandy soil is filled in the mesh holes. The three-dimensional drainage net sheet has the function of collecting sandy soil, which can ensure that the sand is well fixed on the geomembrane on the steep slope without slipping, effectively preventing the problems of sandy soil sliding or geomembrane deformation, avoiding the exposure of the geomembrane to the air and being exposed to wind and sun, preventing the geomembrane from aging and damaging and losing the anti-seepage function, and preventing the geomembrane from being rolled up or even torn by strong winds in harsh environmental conditions such as strong winds. Through environmental test simulation analysis, the protection period can reach more than 15 years, which can meet the use requirements of the tailings pond;

[0022] 2. After the three-dimensional drainage net sheet in the present invention is filled with sandy soil, it has the functions of drainage and seepage, can effectively resist the scouring effect of rainwater, and effectively reduce the phreatic line of the tailings dam through the seepage effect, improving the stability of the dam body; although the slope of the reservoir area is relatively steep, the sand collection function of the three-dimensional drainage net sheet prevents the sliding of the sandy soil and prevents the geomembrane from being torn and damaged due to sliding deformation;

[0023] 3. The three-dimensional drainage net sheet and the sandy soil filled therein in the present invention provide good protection for the geomembrane, can play a buffering role, prevent the damage of the geomembrane by falling objects, the construction is convenient and safe, the quality is easy to guarantee, and it ensures that the geomembrane is not pierced and damaged by external forces;

[0024] 4. In the present invention, a cushion layer is laid between the geomembrane and the foundation to prevent the gravel on the foundation from piercing the geomembrane. By setting double protection structures above and below the geomembrane, the protection time can be effectively extended;

[0025] 5. The method of the present invention is convenient for construction, safe, environmentally friendly, the quality of the geomembrane is easy to guarantee, and it has good social and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic cross-sectional view of the protection structure for laying a geomembrane on the steep slope of the tailings pond reservoir area;

[0027] Figure 2 is a schematic structural view of the three-dimensional drainage net sheet in the present invention.

[0028] In the figure: 1 - foundation; 2 - cushion layer; 3 - geomembrane; 4 - three-dimensional drainage net sheet; 5 - sandy soil; 6 - tailings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] As Figure 1 , Figure 2 shown, a protective structure for laying a geomembrane on a steep slope in a tailings reservoir area. A cushion layer 2 and a geomembrane 3 are sequentially laid on the surface layer of the foundation 1. A three-dimensional drainage net sheet 4 is laid on the surface layer of the geomembrane 3. Multiple irregular holes are provided on the surface and inside of the three-dimensional drainage net sheet 4. Sands 5 are filled in the pores of the three-dimensional drainage net sheet 4.

[0030] The aperture of the irregular holes is 10 mm - 30 mm. The opening density of the irregular holes is 15% - 20%.

[0031] The three-dimensional drainage net sheet 4 is made of a new material formed by randomly melting and laying the filaments, with high pressure resistance. Irregular holes are opened in three dimensions respectively and can be obtained through commercial purchase channels. The thickness of the three-dimensional drainage net sheet 4 is 100 mm - 200 mm.

[0032] The particle size of the sands 5 is 0.5 mm - 10 mm.

[0033] The cushion layer 2 is made of a bentonite blanket with a specification of 4000 g / m 2 - 6000 g / m 2 .

[0034] The geomembrane 3 is made of a geosynthetic material with tensile strength, tear resistance and anti-seepage performance. The thickness of the geomembrane 3 is 1.5 mm - 3.0 mm.

[0035] The slope of the reservoir area is greater than 1:3.0.

[0036] The tailings 6 are the ores with the lowest grade of valuable minerals after ore dressing and other comprehensive utilization treatments.

[0037] A method for protecting a steep slope in a tailings reservoir area by laying a geomembrane includes the following steps:

[0038] A. Remove the humus soil and irregular sharp stones on the surface layer of the reservoir area, level the foundation 1, and then lay the cushion layer 2 on the surface layer of the foundation 1;

[0039] B. Gradually lay the geomembrane 3 anti-seepage layer on the laid cushion layer 2 and anchor it well;

[0040] C. Lay the three-dimensional drainage net sheet 4 on the laid geomembrane 3, and then fill the pores of the three-dimensional drainage net sheet 4 with sands 5.

[0041] After the tailings are discharged to the corresponding elevation in the later stage, cover the tailings on the three-dimensional drainage net sheet 4.

[0042] The present invention is a new technical solution for laying geomembranes on steep slopes in tailings reservoirs over a large area, which prevents the geomembrane from aging and losing its anti-seepage function. The performance of the three-dimensional drainage net sheet 4 for 15 years is simulated by an environmental accelerated simulation degradation experiment. The three-dimensional drainage net sheet 4 is severely degraded in the 15th year, and the residual strength is 5kpa-8kpa, which basically maintains stability. It can be seen from the experiment that the protection time of the method of the present invention can be as long as 15 years or more. At the same time, the present invention has the function of drainage in rainy season and drainage in the later stage of tailings discharge, which can effectively reduce the infiltration line of the tailings dam and prevent the tearing damage of the geomembrane caused by sliding deformation.

Claims

1. A protective structure for laying geomembrane on a steep slope in a tailings reservoir area, characterized in that: On the surface layer of the foundation (1), a cushion layer (2) and a geomembrane (3) are successively laid. On the surface layer of the geomembrane (3), a three-dimensional drainage net sheet material (4) is laid. Multiple irregular holes are provided on the surface and inside of the three-dimensional drainage net sheet material (4), and the pores of the three-dimensional drainage net sheet material (4) are filled with sandy soil (5). The aperture of the irregular holes is 10 mm - 30 mm; The opening density of the irregular holes is 15% - 20%; The thickness of the three-dimensional drainage net sheet material (4) is 100 mm - 200 mm; The slope of the reservoir area is greater than 1:3.0; The cushion layer (2) is made of bentonite carpet with a specification of 4000 g / m 2 - 6000 g / m 2 ; The thickness of the geomembrane (3) is 1.5 mm - 3.0 mm; The particle size of the sandy soil (5) is 0.5 mm - 10 mm.

2. A construction method of a protection structure for laying geomembrane on a steep slope in the tailings pond area according to claim 1, characterized in that, It includes the following steps: A. Remove the humus soil and irregular sharp stones on the surface layer of the reservoir area, and level the foundation (1), and then lay the cushion layer (2) on the surface layer of the foundation (1); B. Lay the geomembrane (3) anti-seepage layer on the laid cushion layer (2) and anchor it well; C. Lay the three-dimensional drainage net sheet material (4) on the laid geomembrane (3), and then fill the pores of the three-dimensional drainage net sheet material (4) with sandy soil (5).

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