Study of possibility application of anti-erosion coating - geomate with ground and sowing of permanent grasses

. Geosynthetic materials are considered modern, reliable, and durable building materials used in many construction areas. Geosynthetic building materials provide a viable and long-term economic alternative to conventional building materials. During the operation of hydraulic structures, they are affected by water and air erosion; the impact of these processes can lead to negative consequences, as a result of which erosion and destruction of structures are possible. To eliminate such consequences, choosing the right protective anti-erosion material and the slope fastening design is necessary. Common geosynthetic materials are geomats, which have found their application in construction. Like other geosynthetic materials, geomats have a fairly wide range of applications in hydraulic engineering construction. This study aimed to study the options for using a geomat with vegetation, namely the selection and selection of a mixture of herbs and the formation of herbage for further application of anti-erosion coating. Currently, the issue of increasing environmental factors is quite acute. This coating will give the slope a natural look without losing protective properties. Also, thanks to the sowing of perennial grasses, the use of this coating will increase the environmental characteristics of the structure, which will favorably affect flora and fauna.


Introduction
Bank protection includes a set of works to strengthen and protect the coastal line natural and artificial reservoirs from undermining, collapse, and erosion of the coastal slope under the influence of currents and waves, as well as erosion by storm flows.An uncontrolled flow of water can devastate the banks and channels of canals, contributing to their shifts, erosion, erosion, and other negative consequences.Water flow can seriously damage nearby roads or buildings along the coast.It is possible to prevent the negative impact of water on the integrity of the channels of water bodies with the help of engineering solutions using high-tech geosynthetic materials [1].
Geomats are three-dimensional, permeable, chaotic structures made of thermally bonded polymeric materials used to fix soil parts, grass roots, or small plants.General properties for geomats: resistance to the chemical composition of natural water, i.e., do not lose their properties in fresh and salt water; resistance to chemical influences; resistance to microorganisms; resistance to temperatures from -30°С to 100°С; resistance to ultraviolet radiation; not toxicity.
Erosion control mats are applied on slopes to increase resistance to erosion caused by rainfall and act as a surface reinforcement until vegetation appears.In certain cases, geomats can be used as erosion protection on the banks of canals and small rivers [2].
When strengthening slopes, geomats perform the following functions: protective in the form of a coating on the slope; reinforcement -increasing the stability of soils of the surface slope zone; filter -preventing the removal of particles by groundwater.As a rule, geomats are combined with biological types of fortifications.The geomat should be located between two layers of plant soil; such a design will be optimal, provide the fastest seed germination and the best reinforcement of the root system, and create the greatest resistance to erosion processes [3].
Backfilling of vegetable soil over geomats is carried out using excavators and front-end loaders from top to bottom, and leveling and compaction of the soil are carried out with a gradual movement along the front line of work.
Using a geomat to fix the vegetation cover increases the resistance of the soil to erosion, which, under certain conditions, serves as an alternative to hard slope clothing.
Due to a special production method, about 90 percent of voids are formed in the geomat structure, which allows it to be used as a reinforcing material.These voids are filled with soil with seeds of perennial grasses.Due to the reinforcing properties of the geomat, the soil in its structure does not crumble.The roots of grass sowing wrap around the geomat threads and more reliably fix the soil in the geomat structure [4][5][6].Due to the above properties, the geomat is excellent for filling it with soil with seeds of perennial grasses.In this paper, a comparison is made between samples of geomat with aggregate in the form of soil, in which various varieties of perennial grasses are sown.

Materials and methods
The experiment on selecting a variety of perennial grasses for germination through a geomat was carried out in four stages.During the experiment, samples were made using an anti-erosion coating consisting of a geomat with soil filler and sowing of perennial grasses.
The obtained samples were kept in a heated room with a constant temperature of 16-20 °C.Four samples of the anti-erosion coating were made for the experiment.In all samples, a base made of geomat was used.Geomat samples were laid on the base soil; after laying in the geomat structure, the soil was filled, which was sown with seeds of perennial grasses.
The first sample was sown with seeds of the «Ryegrass» variety.These seeds, for the first year after planting, form a beautiful, dense lawn.The root system of the cereal is quite powerful, highly branched, quickly penetrates the soil, and forms a good turf.Grass stems are articulated ascending or erect; in the lower part, it has sufficient leaves.
The second sample was sown with a «Mixture of herbs», consisting of the following varieties: perennial ryegrass -50%, red fescue -15%, meadow fescue -20%, meadow timothy grass -15%.These seeds are not demanding on growing conditions.In the first year after planting the seeds, a beautiful, dense lawn is formed, but the shoots appear on the aerial part of the plant.Only one node can be seen in the root system.
The third sample was completely sown with red fescue grass.This variety is undemanding to growing conditions, is characterized by considerable durability, is frost-resistant, drought-resistant, and highly competitive.Red fescue is a rhizomatous-loose bush, grassroots, perennial grass that forms a strong turf.
Perennial rhizomatous, loose bush grass.The variety «Meadow grass meadow» was sown in the fourth sample.In the year of sowing, it grows slowly.Due to the predominance of low-growing vegetative shoots, when mowing, meadow bluegrass retains a significantly larger leaf surface.
This study aimed to study the options for using a geomat with vegetation, namely the selection and selection of a mixture of herbs and the formation of herbage for further application of anti-erosion coating.

Results and Discussion
The study aimed to study the features of the formation of herbage for the further use of an anti-erosion coating consisting of a geomat filled with soil with the sowing of perennial grasses.
As a result of the experiment, four samples of the anti-erosion coating were obtained, consisting of a geomat with soil filler and sowing of perennial grasses (ryegrass, a mixture of grasses, red fescue, meadow bluegrass).
In the process of grass germination, the samples were visually observed.Three out of four samples performed best; they were distinguished by uniform density; these were samples with grass varieties: «Ryegrass», «Red Fescue» and «Mixed Herbs».
The height of all herbage samples for the first 4 days of the experiment did not differ much; in the remaining two weeks of the experiment, the height of the herbage began to change: «Mixed herbs» began to increase every day by 0.5 mm -1 cm, «Ryegrass» began to increase by 1 cm, «Red fescue» by 1 cm, «Meadow grass meadow» by 0.3 -0.5 mm.At the end of the experiment, the growth height of the herbage of four samples corresponded to: «Ryegrass» and «Mixed herbs» -13.5-14 cm, «Red fescue» -7 cm, «Meadow grass meadow» did not exceed 4.5 cm.Then the growth of herbage completely stopped.Next, samples of anti-erosion coatings were evaluated, consisting of a geomat with soil filler and sowing of perennial grasses; the evaluation results are detailed in Table 1.  1, a graph of the dependence of the height of the herbage on the growing season was drawn up, shown in (Fig. 1).

Fig. 1. The dependence of the height of the herbage on the growing season
After the experiment, cuts were made to all four samples to compare their root system.Note that during the experiment, the cessation of vegetation was noted in all four samples.After the cessation of vegetation, the mixture of herbs (sample number 2) began to deteriorate its properties compared to other types of samples.
(Fig. 2) shows a section of the first sample of anti-erosion material -a geomat with soil sown with «Ryegrass» grass.

Fig. 2. Section of anti-erosion material -geomat with soil sown with «Ryegrass» grass
From the section of the first sample, it can be concluded that due to the reinforcing properties of the geomat, the soil in its structure does not crumble.The roots of grass sowing wrap around the geomat threads and more reliably fix the soil in the geomat structure; they also have significant cohesion, density, and elasticity.

Fig. 3. Section of anti-erosion material -geomat and a mixture of herbs
From the section of the second sample, it can be concluded that the roots of the grass seeding of the mixture do not completely wrap around the geomat threads and fix the soil in the geomat structure worse.The root system is superficial, thin, branched, and fragile.
The section of the third sample anti-erosion material -geomat and grass of the «Red Fescue» variety, is shown in (Fig. 4).

Fig. 4. Section of anti-erosion material -geomat and grass of the «Red Fescue» variety
From the section of the third sample, it can be concluded that the turf of «Red Fescue» has significant cohesion, density, and elasticity.The roots of grass sowing wrap around the geomat threads and thereby form a strong turf, which securely fixes the soil in the geomat structure.Note that «Red Fescue» is a rhizome-loose bush, grassroots, perennial grass.
The section of the fourth sample of anti-erosion material -geomat and grass variety «Meadow grass meadow» is shown in (Fig. 5).

Fig. 5. Section of anti-erosion material -geomat and grass of the «Meadow grass meadow» variety
The fourth section concludes that «Meadow grass meadow» forms an even, uniform herbage.The root system wraps around the threads of the geomat, but not completely; the leaf blade is not very thin, like that of Red Fescue, but not as coarse as that of perennial Ryegrass; it grows slowly in the year of sowing.It is also worth noting that «Meadow grass meadow» is perennial rhizomatous loose bushy grassland.threads and more reliably fix the soil in the structure.The samples have significant connectivity, density, and elasticity.The remaining two samples, «Mix of herbs» and «Meadow grass meadow,» showed poor qualities.In these samples, the root system does not completely wrap around the geomat threads and thus fix the soil worse in the structure of the anti-erosion coating.After the experiment, the duration of which was 18 days, there was a cessation of the vegetation of all four samples.

Table 1 .
The results of the study of samples of anti-erosion coatings, consisting of a geomat with soil filler and sowing of perennial grasses