[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention, but the examples cited are not intended to limit the present invention.
[0028] Such as figure 1 with 2 As shown, the composite barrier 1 of the present invention for blocking the horizontal migration of groundwater layer pollutants is composed of a water-soluble polymer film 11 encapsulating swelling clay 10.
[0029] The requirement of the present invention for the swellable clay 10 is that when the water-soluble polymer film 11 is dissolved, the swellable clay 10 will expand with water, and its expansion coefficient is ≥10 times. The clay after expansion can form a permeability coefficient ≤0.5×10 -8 The impervious wall of cm/sec is used to block the horizontal migration of pollutants in the groundwater layer. After experimental screening, the expansive clay 10 of the present invention is one or a combination of sodium bentonite or attapulgite clay.
[0030] In the present invention, the type and thickness of the water-soluble polymer film 11 can be selected and adjusted according to the actual water-soluble time required, and it can be a single layer or a combination of multiple layers. Since the composite barrier 1 is required to be placed in the wall-protecting mud into the vertical slotting process in the present invention, the structure of the composite barrier 1 is intact (that is, the water-soluble polymer film 11 cannot be dissolved and the swellable clay 10 is in contact with water), After being put into the bottom of the vertical slot and backfilled with soil, the water-soluble polymer film 11 is completely dissolved in a certain period of time so that the swellable clay 10 interacts with water to expand, so that the bottom of the slot in the vertical slot reaches the upper surface of the groundwater layer. A layer of clay impervious wall is formed at the place to block the horizontal migration of pollutants in the groundwater layer. For this reason, the high molecular polymer film preferably has the following properties: the high molecular polymer film starts to dissolve after 5 minutes in water.
[0031] The water-soluble polymer film 11 includes one or a combination of polyacrylic acid, polyethylene oxide, or polyvinyl alcohol. The film thickness is 0.025~0.2mm. Preferably, the water-soluble polymer film 11 is mainly composed of polyvinyl alcohol 1788 with an alcoholysis degree of 88%, a medium polymer, and polyacrylic acid. More preferably, the water-soluble polymer film 11 is prepared by the following method: an alcoholysis degree of 88%, a medium polymer polyvinyl alcohol 1788 and polyacrylic acid (mass ratio 9:1) blended resin 80-85 parts, water 3-4 parts, plasticizer 10-14 parts, stabilizer 0.5-1, fast solvent 0.5-1, release agent 0.5-1. It is obtained by melt extrusion blow molding process. The thickness of the water-soluble polymer film 11 is 0.05 mm. The high molecular polymer film prepared by this method has the following properties: warm water solubility; in water at 20-25°C, it starts to dissolve after 5 minutes.
[0032] Hereinafter, the present invention will be explained by using the above-mentioned composite barrier 1 to block the horizontal diffusion and migration of pollutants in the groundwater layer. The method includes the following steps:
[0033] 1) Slotting: Slot 2 vertically at the position where the horizontal migration of pollutants in the groundwater layer needs to be blocked (using mud to protect the wall during the slotting process), to the bottom of the slot is the impervious layer 400 in the geological structure (such as figure 2 As shown, the vertical slot 2 penetrates the soil layer 100, the middle layer 200 and the groundwater layer 300 in the stratum, and can optionally penetrate a part of the impermeable layer 400), and the impermeable layer 400 is mostly a rock layer.
[0034] 2) Preparation of composite barrier 1 to block the horizontal diffusion and migration of 300 pollutants in the groundwater layer:
[0035] a. Preparation of water-soluble polymer film 11;
[0036] It is prepared by the following method: alcoholysis degree 88%, medium polymer polyvinyl alcohol 1788 and polyacrylic acid (mass ratio 9:1) blend resin 80-85 parts, water 3-4 parts, plasticizer 10-14 parts , Stabilizer 0.5-1 part, fast solvent 0.5-1 part, release agent 0.5-1 part. It is obtained by melt extrusion blow molding process. The thickness of the water-soluble polymer film 11 is 0.05 mm.
[0037] b encapsulating sodium bentonite with the water-soluble polymer film 11 prepared above;
[0038] 3) Put the composite barrier 1 in the wall protection slurry of the vertical slot 2 into the vertical slot 2 while ensuring that the composite barrier 1 remains intact during the putting process; the filling height of the composite barrier 1 in the vertical slot 2 No lower than the upper level of the groundwater layer;
[0039] Such as image 3 As shown, in an embodiment of the present invention, the composite barrier 1 has a rectangular parallelepiped shape, its length and width are the same as the bottom of the vertical slot 2, and its height is not lower than the height of the bottom of the tank to the upper plane of the groundwater layer; A composite barrier 1 is filled in the vertical slot 2. Such as Figure 5 As shown, in another embodiment of the present invention, the composite barrier 1 is cylindrical, spherical or polygonal with a cross-sectional width smaller than the width of the bottom of the groove; a plurality of composite barriers 1 are filled in the vertical slot 2 until the composite barrier 1 is The filling height of the vertical slot 2 is not lower than the upper plane of the groundwater layer 300.
[0040] With this, such as Figure 4 As shown, after the outer water-soluble polymer film 11 of the composite barrier 1 is water-soluble, the inner sodium bentonite will contact with water and expand to form a clay impermeable wall, which can block pollutants at the level of the groundwater layer 300 Migration, effectively protect unpolluted groundwater bodies. In addition, the swelling clay will penetrate into the rock crevices of the impermeable layer 400 to further block the diffusion of pollutants from the bottom of the tank.
[0041] 4) Remove the wall protection slurry, and backfill the vertical slot 2 with soil until the vertical slot 2 is filled.
[0042] The composite barrier 1 can be placed in a vertically slotted groundwater layer downstream of or around the polluted area.
[0043] The invention utilizes the anti-seepage property of clay to establish physical shielding of the contaminated area, has the advantages of low cost, good anti-seepage effect, etc., and can withstand a certain hydrostatic pressure at the same time, and has strong resistance to high sulfate or free carbonate environments. Adaptability, can overcome technical defects such as cement grouting and chemical grouting. In addition, due to the continuous swelling of clay minerals, the clay is not afraid of the dilution and erosion of groundwater, nor is it eroded by soluble salts or acids. The composite barrier 1 of the present invention can be widely used to block and shield groundwater layer pollutants, and has good technical and economic feasibility.
[0044] The above-mentioned embodiments are only preferred embodiments for fully explaining the present invention, and the protection scope of the present invention is not limited thereto. The equivalent substitutions or changes made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention is subject to the claims.
