阅读说明：本技术 防止污染物扩散的原位阻隔卷材、制备方法及施工方法 (In-situ barrier coiled material for preventing pollutant from diffusing, preparation method and construction method ) 是由 王冬冬 李来顺 朱湖地 李淑彩 吕正勇 朱宗强 任贝 苗竹 冯坤 于 2019-10-16 设计创作，主要内容包括：本发明公开了一种防止污染物扩散的原位阻隔卷材、制备方法及施工方法,包括：由下至上依次设置第一无纺土工布层、第一铁基生物炭层、第二无纺土工布层、第二铁基生物炭层和第三无纺土工布层；第一无纺土工布层、第二无纺土工布层和第三无纺土工布层通过针刺纤维固定连接。本发明的原位阻隔卷材具有易操作施工,节约建设成本等特点,可以有效的原位修复土壤、底泥及地下水中的重金属污染物,能够适应恶劣的施工和应用环境,具有良好的应用前景。(The invention discloses an in-situ barrier coiled material for preventing pollutant diffusion, a preparation method and a construction method, wherein the preparation method comprises the following steps: the first non-woven geotextile layer, the first iron-based biochar layer, the second non-woven geotextile layer, the second iron-based biochar layer and the third non-woven geotextile layer are arranged from bottom to top in sequence; the first non-woven geotextile layer, the second non-woven geotextile layer and the third non-woven geotextile layer are fixedly connected through the needle-punched fibers. The in-situ blocking coiled material has the characteristics of easiness in operation and construction, construction cost saving and the like, can effectively repair heavy metal pollutants in soil, bottom mud and underground water in situ, can adapt to severe construction and application environments, and has a good application prospect.)

1. An in situ barrier web for preventing diffusion of contaminants, comprising:

the first non-woven geotextile layer, the first iron-based biochar layer, the second non-woven geotextile layer, the second iron-based biochar layer and the third non-woven geotextile layer are arranged from bottom to top in sequence;

the first non-woven geotextile layer, the second non-woven geotextile layer and the third non-woven geotextile layer are fixedly connected through the needle-punched fibers.

2. The in situ barrier web of claim 1, further comprising: a sodium hexametaphosphate modified bentonite layer and a fourth non-woven geotextile layer;

the sodium hexametaphosphate modified bentonite layer and the fourth non-woven geotextile layer are arranged between the first non-woven geotextile layer and the first iron-based biochar layer, and the sodium hexametaphosphate modified bentonite layer is arranged between the first non-woven geotextile layer and the fourth non-woven geotextile layer;

the first non-woven geotextile layer, the second non-woven geotextile layer, the third non-woven geotextile layer and the fourth non-woven geotextile layer are fixedly connected through the needle-punched fibers.

3. The in situ barrier web of claim 1, further comprising: a third iron-based biochar layer and a fourth non-woven geotextile layer;

the third iron-based biochar layer and the fourth non-woven geotextile layer are arranged between the first non-woven geotextile layer and the first iron-based biochar layer, and the third iron-based biochar layer is arranged between the first non-woven geotextile layer and the fourth non-woven geotextile layer;

the first non-woven geotextile layer, the second non-woven geotextile layer, the third non-woven geotextile layer and the fourth non-woven geotextile layer are fixedly connected through the needle-punched fibers.

4. The in-situ barrier roll of any one of claims 1 to 3, wherein the first and third nonwoven geotextile layers are 200 to 230g/m²The polypropylene filament non-woven geotextile.

5. The in-situ barrier web as claimed in any one of claims 2 to 3, wherein the second and fourth non-woven geotextile layers are 100 to 150g/m²The polypropylene filament non-woven geotextile.

6. As claimed in claim2 the in-situ barrier coiled material is characterized in that the sodium hexametaphosphate modified bentonite layer is 4800g/m²The sodium hexametaphosphate modified bentonite is used as an impermeable layer;

the mixing amount of sodium hexametaphosphate in the sodium hexametaphosphate modified bentonite is 3-5% of the mass of the bentonite, the particle size of the sodium hexametaphosphate modified bentonite is less than or equal to 0.15mm, and the permeability coefficient is less than or equal to 5 multiplied by 10^-9m/s。

7. The in-situ barrier coil of claim 3, wherein the preparation method of the iron-based biochar of the first iron-based biochar layer, the second iron-based biochar layer or the third iron-based biochar layer comprises the following steps:

one or more biomasses of roots, stems and leaves of woody plants are taken as raw materials, and one or more iron-containing compounds of zero-valent iron powder, ferrous sulfate or ferric sulfate are added, so that the mass percentage of carbon to iron is (20-50): 1;

adding a sodium borohydride reducing agent solution which accounts for 1-10% of the total mass of the biomass raw material and the iron compound, and carbonizing at the high temperature of 300-800 ℃ to form the biomass material with the specific surface area of 80-150 g/m²The iron-based biochar.

8. The in situ barrier web of any one of claims 1 to 3, wherein the barrier web has a tensile strength > 600N/100mm, an elongation > 15%, and a peel strength > 40N/100 mm.

9. The method for preparing the in-situ barrier coil as claimed in any one of claims 1 to 3, wherein the method comprises the following steps:

laying a first iron-based biochar layer on the first non-woven geotextile layer;

laying a second non-woven geotextile layer on the first iron-based biochar layer;

laying a second iron-based biochar layer on the second non-woven geotextile layer;

laying a third non-woven geotextile layer on the second iron-based biochar layer;

fixing the first, second and third non-woven geotextile layers by needle-punched fibers;

alternatively, the first and second electrodes may be,

laying a sodium hexametaphosphate modified bentonite layer on the first non-woven geotextile layer;

laying a fourth non-woven geotextile layer on the sodium hexametaphosphate modified bentonite layer;

laying a first iron-based biochar layer on the fourth non-woven geotextile layer;

laying a second non-woven geotextile layer on the first iron-based biochar layer;

laying a second iron-based biochar layer on the second non-woven geotextile layer;

laying a third non-woven geotextile layer on the second iron-based biochar layer;

fixing the first, second, third and fourth non-woven geotextile layers by needle-punched fibers;

alternatively, the first and second electrodes may be,

paving a third iron-based biochar layer on the first nonwoven geotextile layer;

laying a fourth non-woven geotextile layer on the third iron-based biochar layer;

laying a first iron-based biochar layer on the fourth non-woven geotextile layer;

laying a second non-woven geotextile layer on the first iron-based biochar layer;

laying a second iron-based biochar layer on the second non-woven geotextile layer;

laying a third non-woven geotextile layer on the second iron-based biochar layer;

and fixing the first non-woven geotextile layer, the second non-woven geotextile layer, the third non-woven geotextile layer and the fourth non-woven geotextile layer through needling fibers.

10. The construction method of the in-situ barrier coiled material as claimed in any one of claims 1 to 3, wherein the construction method comprises the following steps:

the in-situ blocking coiled material is vertically paved at the downstream of the groundwater flow of the polluted site to block and remove the migration of the heavy metal pollutants in the groundwater;

the in-situ blocking coiled material is horizontally paved on the upper layer of the polluted soil or the polluted bottom mud to block and remove the migration of pollutants in the soil or the heavy metal percolate of the bottom mud.

Technical Field

The invention relates to the technical field of contaminated soil, bottom mud and underground water remediation engineering, in particular to an in-situ barrier coiled material for preventing diffusion of pollutants, a preparation method and a construction method.

Background

With the rapid development of economic society, the production activities and social behaviors of human beings bring certain influence on the natural environment. The production behaviors in the fields of mineral exploitation, metal smelting, chemical production and the like threaten the environments such as surrounding soil, bottom mud, river water and the like, heavy metal pollution is one of the environments, and the main pollution sources of the heavy metal pollution are waste water, waste residues and the like discharged from mining areas, smelting plants, electroplating plants, tanneries and pigment plants. Heavy metals contained in these pollutants can enter underground water through surface runoff, rainwater leaching and the like, and further pollute underground water resources available to human beings.

The problem of heavy metal pollution in soil, river sediment and the groundwater is solved to normal position restoration or dystopy restoration technique commonly used at present, but dystopy restoration technique is with high costs, easily causes secondary pollution, has certain limitation. Therefore, the method and the repair material which are time-saving, efficient, cheap, good in treatment effect, environment-friendly and the like are urgently needed to be explored, and the problem of heavy metal pollution migration and diffusion is solved. On the one hand, domestic methods for treating pollution of polluted soil, river sediment and underground water are more, and the methods mainly comprise physical control, chemical remediation, electric remediation technologies and the like. On the other hand, in the fields of municipal administration, water conservancy, refuse landfill, mines and the like, the sodium bentonite waterproof blanket is widely applied due to excellent seepage-proofing performance, simple processing, convenient construction and the like, while the common bentonite waterproof blanket has single function, can only play a good role in preventing water and seepage, and has weak capacity of preventing heavy metal pollution.

Disclosure of Invention

Aiming at the defects in the problems, the invention provides the in-situ barrier coiled material for preventing the diffusion of pollutants, the preparation method and the construction method, which are used for in-situ remediation of the migration and diffusion of heavy metal polluted soil, bottom mud and underground water.

A first object of the present invention is to provide an in-situ barrier web for preventing diffusion of contaminants, comprising:

the first non-woven geotextile layer, the first iron-based biochar layer, the second non-woven geotextile layer, the second iron-based biochar layer and the third non-woven geotextile layer are arranged from bottom to top in sequence;

the first non-woven geotextile layer, the second non-woven geotextile layer and the third non-woven geotextile layer are fixedly connected through the needle-punched fibers.

As a further improvement of the invention, the method also comprises the following steps: a sodium hexametaphosphate modified bentonite layer and a fourth non-woven geotextile layer;

the sodium hexametaphosphate modified bentonite layer and the fourth non-woven geotextile layer are arranged between the first non-woven geotextile layer and the first iron-based biochar layer, and the sodium hexametaphosphate modified bentonite layer is arranged between the first non-woven geotextile layer and the fourth non-woven geotextile layer;

the first non-woven geotextile layer, the second non-woven geotextile layer, the third non-woven geotextile layer and the fourth non-woven geotextile layer are fixedly connected through the needle-punched fibers.

As a further improvement of the invention, the method also comprises the following steps: a third iron-based biochar layer and a fourth non-woven geotextile layer;

the third iron-based biochar layer and the fourth non-woven geotextile layer are arranged between the first non-woven geotextile layer and the first iron-based biochar layer, and the third iron-based biochar layer is arranged between the first non-woven geotextile layer and the fourth non-woven geotextile layer;

the first non-woven geotextile layer, the second non-woven geotextile layer, the third non-woven geotextile layer and the fourth non-woven geotextile layer are fixedly connected through the needle-punched fibers.

As a further improvement of the invention, the first non-woven geotextile layer and the third non-woven geotextile layer are 200-230 g/m²The polypropylene filament non-woven geotextile.

As a further improvement of the invention, the second non-woven geotextile layer and the fourth non-woven geotextile layer are 100-150 g/m²The polypropylene filament non-woven geotextile.

As a further improvement of the invention, the sodium hexametaphosphate modified bentonite layer is 4800g/m²The sodium hexametaphosphate modified bentonite is used as an impermeable layer;

the mixing amount of sodium hexametaphosphate in the sodium hexametaphosphate modified bentonite is 3-5% of the mass of the bentonite, the particle size of the sodium hexametaphosphate modified bentonite is less than or equal to 0.15mm, and the permeability coefficient is less than or equal to 5 multiplied by 10^-9m/s。

As a further improvement of the present invention, the preparation method of the iron-based biochar of the first iron-based biochar layer, the second iron-based biochar layer or the third iron-based biochar layer comprises:

one or more biomasses of roots, stems and leaves of woody plants are taken as raw materials, and one or more iron-containing compounds of zero-valent iron powder, ferrous sulfate or ferric sulfate are added, so that the mass percentage of carbon to iron is (20-50): 1;

adding a sodium borohydride reducing agent solution which accounts for 1-10% of the total mass of the biomass raw material and the iron compound, and carbonizing at the high temperature of 300-800 ℃ to form the biomass material with the specific surface area of 80-150 g/m²The iron-based biochar.

As a further improvement of the invention, the barrier web has a tensile strength > 600N/100mm, an elongation > 15%, and a peel strength > 40N/100 mm.

A second object of the present invention is to provide a method for preparing an in-situ barrier roll, comprising:

laying a first iron-based biochar layer on the first non-woven geotextile layer;

laying a second non-woven geotextile layer on the first iron-based biochar layer;

laying a second iron-based biochar layer on the second non-woven geotextile layer;

laying a third non-woven geotextile layer on the second iron-based biochar layer;

fixing the first, second and third non-woven geotextile layers by needle-punched fibers;

alternatively, the first and second electrodes may be,

laying a sodium hexametaphosphate modified bentonite layer on the first non-woven geotextile layer;

laying a fourth non-woven geotextile layer on the sodium hexametaphosphate modified bentonite layer;

laying a first iron-based biochar layer on the fourth non-woven geotextile layer;

laying a second non-woven geotextile layer on the first iron-based biochar layer;

laying a second iron-based biochar layer on the second non-woven geotextile layer;

laying a third non-woven geotextile layer on the second iron-based biochar layer;

fixing the first, second, third and fourth non-woven geotextile layers by needle-punched fibers;

alternatively, the first and second electrodes may be,

paving a third iron-based biochar layer on the first nonwoven geotextile layer;

laying a fourth non-woven geotextile layer on the third iron-based biochar layer;

laying a first iron-based biochar layer on the fourth non-woven geotextile layer;

laying a second non-woven geotextile layer on the first iron-based biochar layer;

laying a second iron-based biochar layer on the second non-woven geotextile layer;

laying a third non-woven geotextile layer on the second iron-based biochar layer;

and fixing the first non-woven geotextile layer, the second non-woven geotextile layer, the third non-woven geotextile layer and the fourth non-woven geotextile layer through needling fibers.

The third purpose of the invention is to provide a construction method of the in-situ barrier coiled material, which comprises the following steps:

the in-situ blocking coiled material is vertically paved at the downstream of the groundwater flow of the polluted site to block and remove the migration of the heavy metal pollutants in the groundwater;

the in-situ blocking coiled material is horizontally paved on the upper layer of the polluted soil or the polluted bottom mud to block and remove the migration of pollutants in the soil or the heavy metal percolate of the bottom mud.

Compared with the prior art, the invention has the beneficial effects that:

according to the in-situ barrier coiled material, the heavy metal pollution prevention material and the anti-seepage material are respectively and tightly fixed among the four layers of non-woven geotextiles by means of chemical, physical or biological modification, so that the in-situ barrier coiled material not only has a good heavy metal pollution prevention effect, but also has good anti-seepage performance; the most important characteristic of the invention is that the corresponding heavy metal pollution preventing material layer can be selected according to the pollutant type and the anti-seepage requirement, for example, if the pollution source is hexavalent chromium, the hexavalent chromium can be reduced into trivalent chromium with lower toxicity by a reducing agent material added with zero-valent iron powder, and the trivalent chromium is adsorbed on the surface of the biomass charcoal particles with larger specific surface area. The barrier coiled material can be horizontally laid or vertically laid according to the piling state of the polluted soil and the bottom mud, and the barrier coiled material can play a role in blocking the migration and diffusion of heavy metal pollutants;

compared with the common composite geotechnical blanket which is formed by multiple times of needling, the barrier coiled material is formed by one-time needling, the preparation and construction method is simple and convenient, the mechanical parameters are excellent, the tensile strength is more than 600N/100mm, the elongation is more than 15%, and the peel strength is more than 40N/100 mm;

the in-situ blocking coiled material has the characteristics of easiness in operation and construction, construction cost saving and the like, can effectively repair heavy metal pollutants in soil, bottom mud and underground water in situ, can adapt to severe construction and application environments, and has a good application prospect.

Drawings

FIG. 1 is a schematic view of an in-situ barrier web according to an embodiment of the present disclosure;

FIG. 2 is a schematic illustration of a construction of an in situ barrier web as disclosed in another embodiment of the present invention;

FIG. 3 is a schematic view of a construction of an in situ barrier web as disclosed in another embodiment of the present invention;

figure 4 is a schematic view of a vertical lay-up configuration of an in-situ barrier web according to one embodiment of the present disclosure.

In the figure:

1. a first nonwoven geotextile layer; 2. a first iron-based biochar layer; 3. a second non-woven geotextile layer; 4. a second iron-based biochar layer; 5. a third non-woven geotextile layer; 6. needling the fibers; 7. sodium hexametaphosphate modifies the bentonite layer; 8. a fourth non-woven geotextile layer; 9. a third iron-based biochar layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The invention is described in further detail below with reference to the attached drawing figures:

based on the research of problems in the background art, by comparing the advantages and the disadvantages of various repair technologies and repair materials, the invention transforms the environmental mineral materials into the in-situ barrier coiled material with small particle size, large specific surface area, high porosity and better ion exchange performance by a proper chemical, physical or biological modification means, and provides a convenient preparation method and a construction method of the barrier coiled material for in-situ horizontal or vertical barrier of heavy metal polluted soil, bottom mud and underground water.

Specifically, the method comprises the following steps:

as shown in fig. 1, the present invention provides an in situ barrier web for preventing the diffusion of contaminants, comprising:

the first non-woven geotextile layer 1, the first iron-based biochar layer 2, the second non-woven geotextile layer 3, the second iron-based biochar layer 4 and the third non-woven geotextile layer 5 are arranged from bottom to top in sequence;

the first non-woven geotextile layer 1, the second non-woven geotextile layer 3 and the third non-woven geotextile layer 5 are fixedly connected through the needle-punched fibers 6, and the first iron-based biochar layer 2 and the second iron-based biochar layer 4 are fixed between the two non-woven geotextile layers, so that all the layers are connected and fixed together.

Wherein, the first iron-based biochar layer 2 and the second iron-based biochar layer 4 are used as heavy metal pollutant diffusion prevention layers.

As shown in fig. 2, the present invention provides an in situ barrier web for preventing the diffusion of contaminants, comprising:

a first non-woven geotextile layer 1, a sodium hexametaphosphate modified bentonite layer 7, a fourth non-woven geotextile layer 8, a first iron-based biochar layer 2, a second non-woven geotextile layer 3, a second iron-based biochar layer 4 and a third non-woven geotextile layer 5 are arranged from bottom to top in sequence;

the first non-woven geotextile layer 1, the second non-woven geotextile layer 3, the third non-woven geotextile layer 5 and the fourth non-woven geotextile layer 8 are fixedly connected through the needle-punched fibers 6, and the first iron-based biochar layer 2, the sodium hexametaphosphate modified bentonite layer 7 and the second iron-based biochar layer 4 are fixed between the two non-woven geotextile layers, so that all layers are connected and fixed together.

The first iron-based biochar layer 2 and the second iron-based biochar layer 4 are used as heavy metal pollutant diffusion prevention layers, and the sodium hexametaphosphate modified bentonite 7 is used as an anti-seepage layer.

As shown in fig. 3, the present invention provides an in situ barrier web for preventing the diffusion of contaminants, comprising:

a first non-woven geotextile layer 1, a third iron-based biochar layer 9, a fourth non-woven geotextile layer 8, a first iron-based biochar layer 2, a second non-woven geotextile layer 3, a second iron-based biochar layer 4 and a third non-woven geotextile layer 5 are arranged from bottom to top in sequence;

the first non-woven geotextile layer 1, the second non-woven geotextile layer 3, the third non-woven geotextile layer 5 and the fourth non-woven geotextile layer 8 are fixedly connected through the needle-punched fibers 6, and the first iron-based biochar layer 2, the third iron-based biochar layer 9 and the second iron-based biochar layer 4 are fixed between the two non-woven geotextile layers, so that all the layers are connected and fixed together.

Wherein, the first iron-based biochar layer 2, the second iron-based biochar layer 4 and the third iron-based biochar layer 9 are used as heavy metal pollutant diffusion prevention layers.

Further, in the three configurations of in situ barrier webs shown in fig. 1, 2, and 3 described above:

the first non-woven geotextile layer 1 and the third non-woven geotextile layer 5 are 200-230 g/m²The polypropylene filament non-woven geotextile, the second non-woven geotextile layer 3 and the fourth non-woven geotextile layer 8 are 100-150 g/m²The polypropylene filament non-woven geotextile.

The sodium hexametaphosphate modified bentonite layer 7 is prepared from 4800g/m²The sodium hexametaphosphate modified bentonite is prepared from 3-5% of sodium hexametaphosphate in the sodium hexametaphosphate modified bentonite, the particle size of the sodium hexametaphosphate modified bentonite is less than or equal to 0.15mm, and the permeability coefficient is less than or equal to 5 multiplied by 10^-9m/s。

The preparation method of the iron-based biochar of the first iron-based biochar layer 2, the second iron-based biochar layer 4 and the third iron-based biochar layer 9 comprises the following steps:

one or more biomasses of roots, stems and leaves of woody plants are taken as raw materials, and one or more iron-containing compounds of zero-valent iron powder, ferrous sulfate or ferric sulfate are added, so that the mass percentage of carbon to iron is (20-50): 1; adding a sodium borohydride reducing agent solution which accounts for 1-10% of the total mass of the biomass raw material and the iron compound, and carbonizing at the high temperature of 300-800 ℃ to form the biomass material with the specific surface area of 80-150 g/m²The iron-based biochar.

The tensile strength of the in-situ barrier coiled material with the three structures shown in the figures 1, 2 and 3 is more than 600N/100mm, the elongation is more than 15 percent, and the peeling strength is more than 40N/100 mm.

The invention provides a preparation method of an in-situ barrier coil material shown in figure 1, which comprises the following steps:

laying a first iron-based biochar layer 2 on the first non-woven geotextile layer 1;

laying a second non-woven geotextile layer 3 on the first iron-based biochar layer 2;

laying a second iron-based biochar layer 4 on the second non-woven geotextile layer 3;

laying a third non-woven geotextile layer 5 on the second iron-based biochar layer 4;

the first, second and third nonwoven geotextile layers 1, 3 and 5 are fixed by the needle-punched fibers 6.

The invention provides a preparation method of an in-situ barrier coil material shown in figure 2, which comprises the following steps:

laying a sodium hexametaphosphate modified bentonite layer 7 on the first non-woven geotextile layer 1;

laying a fourth non-woven geotextile layer 8 on the sodium hexametaphosphate modified bentonite layer 7;

laying a first iron-based biochar layer 2 on the fourth non-woven geotextile layer 8;

laying a second non-woven geotextile layer 3 on the first iron-based biochar layer 2;

laying a second iron-based biochar layer 4 on the second non-woven geotextile layer 3;

laying a third non-woven geotextile layer 5 on the second iron-based biochar layer 4;

the first non-woven geotextile layer 1, the second non-woven geotextile layer 3, the third non-woven geotextile layer 5, and the fourth non-woven geotextile layer 8 are fixed by the needle-punched fibers 6.

The invention provides a preparation method of an in-situ barrier coil material shown in figure 3, which comprises the following steps:

laying a third iron-based biochar layer 9 on the first non-woven geotextile layer 1;

laying a fourth non-woven geotextile layer 8 on the third iron-based biochar layer 9;

laying a first iron-based biochar layer 2 on the fourth non-woven geotextile layer 8;

laying a second non-woven geotextile layer 3 on the first iron-based biochar layer 2;

laying a second iron-based biochar layer 4 on the second non-woven geotextile layer 3;

laying a third non-woven geotextile layer 5 on the second iron-based biochar layer 4;

the first non-woven geotextile layer 1, the second non-woven geotextile layer 3, the third non-woven geotextile layer 5, and the fourth non-woven geotextile layer 8 are fixed by the needle-punched fibers 6.

The invention provides a construction method of an in-situ barrier coiled material, which comprises the following steps:

the in-situ blocking coiled material is vertically paved at the downstream of the groundwater flow of the polluted site to block and remove the migration of the heavy metal pollutants in the groundwater; the vertical laying mode is shown in figure 4;

the in-situ blocking coiled material is horizontally laid on the upper layer of the polluted soil or the polluted bottom mud, and the migration of pollutants in the soil or the heavy metal percolate of the bottom mud is blocked and removed; the horizontal lay is shown in figures 1, 2 or 3.

The construction method comprises the following steps: the method comprises the steps of measuring the actual dimension of a polluted area, laying and planning, tamping a base layer (horizontal laying) or excavating a groove (vertical laying), producing and processing the barrier coiled material, laying the barrier coiled material, processing the seam of the barrier coiled material, checking and accepting, covering and the like.

The method specifically comprises the following steps:

A. the base layer to be laid is inspected before horizontal laying construction, the base layer is flat and free of accumulated water in pits, stone tree roots and other sharp objects; before vertical laying construction, a groove is dug through grooving equipment, and the laid separation coiled material needs to be clean and free of damage.

B. When the barrier coiled material is vertically laid, the barrier coiled material is safely anchored, then the coiled material is put down along the slope, the stretched coiled material is kept in a tight state, and the position of the stretched coiled material is adjusted to reduce wrinkles on the surface of the material. The connection of the barrier coiled materials adopts a lap joint mode, and both ends of the barrier coiled materials are mechanically anchored. When the barrier coiled material is horizontally laid, the barrier coiled material is naturally loosened when unfolded, and is tightly attached to the supporting layer and cannot be folded or suspended.

C. The connection of the blocking coiled materials adopts a lap joint mode, the lap joint width is 250 +/-50 mm, lap joints are tightly attached and leveled, folding is strictly prohibited, a layer of bulk iron-based biochar particles are uniformly sprayed in a lap joint area, and the using amount of the iron-based biochar particles is not less than 1Kg/m or bentonite waterproof slurry is used for sealing the lap joints.

D. After the installation is finished, the barrier coiled material on the whole pavement surface needs to be checked and accepted to ensure that the paved barrier coiled material for preventing the diffusion of pollutants does not leak.

According to the in-situ barrier coiled material for preventing the diffusion of pollutants, disclosed by the invention, the heavy metal pollution preventing material and the anti-seepage material are respectively and tightly fixed among the four layers of non-woven geotextiles by means of chemical, physical or biological modification, so that a good heavy metal pollution preventing effect is achieved, and the anti-seepage performance is good. The most important characteristic of the invention is that the corresponding heavy metal pollution preventing material layer can be selected according to the pollutant type and the anti-seepage requirement, for example, if the pollution source is hexavalent chromium, the hexavalent chromium can be reduced into trivalent chromium with lower toxicity by a reducing agent material added with zero-valent iron powder, and the trivalent chromium is adsorbed on the surface of the biomass charcoal particles with larger specific surface area. And barrier coiled materials can be horizontally laid or vertically laid according to the stacking state of the polluted soil and the bottom mud, and the barrier coiled materials can play a role in blocking migration and diffusion of heavy metal pollutants. Compared with the common composite geotechnical blanket which is formed by multiple times of needling, the barrier coiled material is formed by one-time needling, the preparation and construction method is simple and convenient, the mechanical parameters are excellent, the tensile strength is more than 600N/100mm, the elongation is more than 15%, and the peel strength is more than 40N/100 mm. The method has the characteristics of simple process flow, easy operation and construction, construction cost saving and the like, can effectively repair heavy metal pollutants in soil, bottom mud and underground water in situ, can adapt to severe construction and application environments, and has good application prospect.