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Taking Sui-Chongqing railway slope as the research object, soil resistivity, soil electrochemistry (corrosion potential, redox potential, potential gradient and pH), soil anions (total soluble salts, Cl-, SO42- and) and soil Nutrition.(Moisture content, organic matter, total nitrogen, alkali-hydrolyzed nitrogen, available phosphorus, available potassium) Under different slopes, the corrosion grade is evaluated according to the individual indicators and comprehensive indicators of artificial soil.Compared with other factors, water has the greatest influence on the corrosion of slope protection net, followed by anion content.The total soluble salt has a moderate effect on the corrosion of the slope protection net, and the stray current has a moderate effect on the corrosion of the slope protection net.The corrosion degree of soil samples was comprehensively evaluated, and the corrosion on the upper slope was moderate, and the corrosion on the middle and lower slopes was strong.The organic matter in the soil was significantly correlated with the potential gradient.Available nitrogen, available potassium and available phosphorus were significantly correlated with anions.The distribution of soil nutrients is indirectly related to the slope type.
When building railways, highways and water conservancy facilities, mountain openings are often unavoidable.Due to the mountains in the southwest, China’s railway construction requires a lot of excavation of the mountain.It destroys the original soil and vegetation, creating exposed rocky slopes.This situation leads to landslides and soil erosion, thus threatening the safety of railway transportation.Landslides are bad for road traffic, especially after the May 12, 2008 Wenchuan earthquake.Landslides have become a widely distributed and serious earthquake disaster1. In the 2008 evaluation of 4,243 kilometers of key trunk roads in Sichuan Province, there were 1,736 severe earthquake disasters in roadbeds and slope retaining walls, accounting for 39.76% of the total length of the evaluation.Direct economic losses from road damage exceeded 58 billion yuan 2,3.Global examples show that post-earthquake geohazards can last for at least 10 years (Taiwan earthquake) and even as long as 40-50 years (Kanto earthquake in Japan)4,5.Gradient is the main factor affecting earthquake hazard6,7.Therefore, it is necessary to maintain the road slope and strengthen its stability.Plants play an irreplaceable role in slope protection and ecological landscape restoration8.Compared with ordinary soil slopes, rock slopes do not have the accumulation of nutrient factors such as organic matter, nitrogen, phosphorus, and potassium, and do not have the soil environment necessary for vegetation growth.Due to factors such as large slope and rain erosion, slope soil is easily lost.The slope environment is harsh, lacks the necessary conditions for plant growth, and the slope soil lacks supporting stability9.Slope spraying with base material to cover soil to protect the slope is a commonly used slope ecological restoration technology in my country.The artificial soil used for spraying is composed of crushed stone, farmland soil, straw, compound fertilizer, water-retaining agent and adhesive (commonly used adhesives include Portland cement, organic glue and asphalt emulsifier) ​​in a certain proportion.The technical process is: first lay barbed wire on the rock, then fix the barbed wire with rivets and anchor bolts, and finally spray artificial soil containing seeds on the slope with a special sprayer.The 14# diamond-shaped metal mesh that is fully galvanized is mostly used, with a mesh standard of 5cm×5cm and a diameter of 2mm.The metal mesh allows the soil matrix to form a durable monolithic slab on the rock surface.The metal mesh will corrode in the soil, because the soil itself is an electrolyte, and the degree of corrosion depends on the characteristics of the soil.The evaluation of soil corrosion factors is of great significance for evaluating soil-induced metal mesh erosion and eliminating landslide hazards.
Plant roots are believed to play a crucial role in slope stabilization and erosion control10,11,12,13,14.To stabilize slopes against shallow landslides, vegetation can be used because plant roots can fix the soil to prevent landslides15,16,17.Woody vegetation, especially trees, helps prevent shallow landslides18.A sturdy protective structure formed by the vertical and lateral root systems of plants that act as reinforcing piles in the soil.The development of root architecture patterns is driven by genes, and the soil environment plays a decisive role in these processes.Corrosion to metals varies with soil environment20.The degree of corrosion of metals in soil can range from fairly rapid dissolution to negligible impact21.Artificial soil is very different from real “soil”.The formation of natural soils is the result of interactions between the external environment and various organisms over tens of millions of years22,23,24.Before the woody vegetation forms a stable root system and ecosystem, whether the metal mesh combined with the rock slope and artificial soil can function safely is directly related to the development of the natural economy, the safety of life and the improvement of the ecological environment.
However, corrosion of metals can lead to huge losses.According to a survey conducted in China in the early 1980s on chemical machinery and other industries, losses caused by metal corrosion accounted for 4% of the total output value.Therefore, it is of great significance to study the corrosion mechanism and take protective measures for economic construction.Soil is a complex system of gases, liquids, solids and microorganisms.Microbial metabolites can corrode materials, and stray currents can also cause corrosion.Therefore, it is important to prevent corrosion of metals buried in soil.At present, the research on buried metal corrosion mainly focuses on (1) factors affecting buried metal corrosion25; (2) metal protection methods26,27; (3) judgment methods for the degree of metal corrosion28; Corrosion in different media.However, all soils in the study were natural and had undergone sufficient soil formation processes.However, there is no report on artificial soil erosion of railway rock slopes.
Compared with other corrosive media, artificial soil has the characteristics of illiquidity, heterogeneity, seasonality and regionality.Metal corrosion in artificial soils is caused by electrochemical interactions between metals and artificial soils.In addition to innate factors, the rate of metal corrosion also depends on the surrounding environment.A variety of factors affect metal corrosion individually or in combination, such as moisture content, oxygen content, total soluble salt content, anion and metal ion content, pH, soil microbes30,31,32.
In 30 years of practice, the question of how to permanently preserve artificial soils on rocky slopes has been a problem33.Shrubs or trees cannot grow on some slopes after 10 years of manual care due to soil erosion.The dirt on the surface of the metal mesh was washed away in some places.Due to corrosion, some metal meshes cracked and lost all soil above and below them (Figure 1).At present, the research on railway slope corrosion mainly focuses on the corrosion of railway substation grounding grid, stray current corrosion generated by light rail, and corrosion of railway bridges34,35, tracks and other vehicle equipment36.There have been no reports of corrosion of the railway slope protection metal mesh.This paper studies the physical, chemical and electrochemical properties of artificial soils on the southwestern rock slope of the Suiyu Railway, aiming to predict metal corrosion by assessing soil properties and provide theoretical and practical basis for soil ecosystem restoration and artificial restoration.Slope artificial.
The test site is located in the hilly area of ​​Sichuan (30°32′N, 105°32′E) near Suining Railway Station.The area is located in the middle of the Sichuan Basin, with low mountains and hills, with simple geological structure and flat terrain.Erosion, cutting and accumulation of water create eroded hilly landscapes.The bedrock is mainly limestone, and the overburden is mainly purple sand and mudstone.The integrity is poor, and the rock is a blocky structure.The study area has a subtropical humid monsoon climate with seasonal characteristics of early spring, hot summer, short autumn and late winter.The rainfall is abundant, the light and heat resources are abundant, the frost-free period is long (285 days on average), the climate is mild, the annual average temperature is 17.4°C, the average temperature of the hottest month (August) is 27.2°C, and the extreme maximum temperature is 39.3°C.The coldest month is January (average temperature is 6.5°C), the extreme minimum temperature is -3.8°C, and the annual average rainfall is 920 mm, mainly concentrated in July and August.The rainfall in spring, summer, autumn and winter varies greatly. The proportion of rainfall in each season of the year is 19-21%, 51-54%, 22-24% and 4-5% respectively.
The research site is a slope of about 45° on the slope of the Yu-Sui Railway built in 2003. In April 2012, it faced south within 1 km of the Suining Railway Station. The natural slope was used as a control.The ecological restoration of the slope adopts the foreign topdressing soil spraying technology for ecological restoration.According to the height of the railway side slope, the slope can be divided into upslope, mid-slope and downslope (Fig. 2).Since the thickness of the cut slope artificial soil is about 10cm, in order to avoid the pollution of the corrosion products of the soil metal mesh, we only use a stainless steel shovel to take the soil surface 0-8cm.Four replicates were set for each slope position, with 15-20 random sampling points per replicate.Each replicate is a mixture of 15-20 randomly determined from S-shaped line sampling points.Its fresh weight is about 500 grams.Bring the samples back to the laboratory in polyethylene ziplock bags for processing.The soil is naturally air-dried, and the gravel and animal and plant residues are picked out, crushed with an agate stick, and sieved with a 20-mesh, 100-mesh nylon sieve except for the coarse particles.
The soil resistivity was measured by the VICTOR4106 grounding resistance tester produced by Shengli Instrument Company; the soil resistivity was measured in the field; the soil moisture was measured by the drying method.The DMP-2 portable digital mv/pH instrument features high input impedance for measuring soil corrosion potential.Potential gradient and redox potential were determined by DMP-2 portable digital mv/pH, total soluble salt in soil was determined by residue drying method, chloride ion content in soil was determined by AgNO3 titration method (Mohr method), soil sulfate content was determined by indirect EDTA Titration method, double indicator titration method to determine soil carbonate and bicarbonate, potassium dichromate oxidation heating method to determine soil organic matter, alkaline solution diffusion method to determine soil alkaline hydrolysis nitrogen, H2SO4-HClO4 digestion Mo-Sb colorimetric method Total phosphorus in soil and available phosphorus content in soil were determined by Olsen method (0.05 mol/L NaHCO3 solution as extractant), and total potassium content in soil was determined by sodium hydroxide fusion-flame photometry.
The experimental data was initially systematized.SPSS Statistics 20 was used to perform mean, standard deviation, one-way ANOVA, and human correlation analysis.
Table 1 presents the electromechanical properties, anions and nutrients of soils with different slopes.The corrosion potential, soil resistivity and east-west potential gradient of different slopes were all significant (P < 0.05).The redox potentials of downhill, mid-slope and natural slope were significant (P < 0.05).The potential gradient perpendicular to the rail, that is, the north-south potential gradient, is upslope>downslope>middle slope.The soil pH value was in the order of downslope>uphill>middle slope>natural slope.Total soluble salt, natural slope was significantly higher than railway slope (P < 0.05).The total soluble salt content of the third-grade railway slope soil is above 500 mg/kg, and the total soluble salt has a moderate effect on metal corrosion.The soil organic matter content was the highest in the natural slope and the lowest in the downhill slope (P < 0.05).The total nitrogen content was the highest in the middle slope and the lowest in the uphill slope; the available nitrogen content was the highest in the downslope and middle slope, and the lowest in the natural slope; the total nitrogen content of the railway upslope and downslope was lower, but the available nitrogen content was higher.This indicates that the uphill and downhill organic nitrogen mineralization rate is fast.Available potassium content is the same as available phosphorus.
Soil resistivity is an index indicating electrical conductivity and a basic parameter for judging soil corrosion.Factors affecting soil resistivity include moisture content, total soluble salt content, pH, soil texture, temperature, organic matter content, soil temperature, and tightness.Generally speaking, soils with low resistivity are more corrosive, and vice versa.Using resistivity to judge soil corrosivity is a method commonly used in various countries.Table 1 shows the corrosivity grade evaluation criteria for each single index37,38.
According to the test results and standards in my country (Table 1), if soil corrosiveness is only evaluated by soil resistivity, the soil on the uphill slope is highly corrosive; the soil on the downhill slope is moderately corrosive; the soil corrosiveness on the middle slope and natural slope is relatively low weak.
The soil resistivity of the uphill slope is significantly lower than that of other parts of the slope, which may be caused by rain erosion.The topsoil on the upslope flows to the middle slope with the water, so that the upslope metal slope protection net is close to the topsoil.Some of the metal meshes were exposed and even suspended in the air (Figure 1).Soil resistivity was measured on site; pile spacing was 3m; pile driving depth was below 15cm.Bare metal mesh and peeling rust can interfere with the measurement results.Therefore, it is unreliable to evaluate soil corrosivity only by soil resistivity index.In the comprehensive evaluation of corrosion, the soil resistivity of upslope is not considered.
Due to the high relative humidity, the perennial humid air in the Sichuan area causes the metal mesh exposed to the air to corrode more seriously than the metal mesh buried in the soil39.Exposure of wire mesh to air can result in decreased service life, which can destabilize uphill soils.Soil loss can make it difficult for plants, especially woody plants, to grow.Due to the lack of woody plants, it is difficult to form a root system uphill to solidify the soil.At the same time, plant growth can also improve soil quality and increase the content of humus in the soil, which can not only retain water, but also provide a good environment for the growth and reproduction of animals and plants, thereby reducing soil loss.Therefore, in the early stage of construction, more woody seeds should be sown on the upslope, and water-retaining agent should be continuously added and covered with film for protection, so as to reduce the erosion of the upslope soil by rainwater.
The corrosion potential is an important factor affecting the corrosion of the slope protection net on the three-level slope, and has the greatest impact on the uphill slope (Table 2).Under normal conditions, the corrosion potential does not change much in a given environment.A noticeable change can be caused by stray currents.Stray currents refer to currents 40, 41, 42 that leak into the roadbed and soil medium when vehicles use the public transport system.With the development of transportation system, my country’s railway transportation system has achieved large-scale electrification, and the corrosion of buried metals caused by direct current leakage from electrified railways cannot be ignored.Currently, the soil potential gradient can be used to determine whether the soil contains stray current disturbances.When the potential gradient of the surface soil is lower than 0.5 mv/m, the stray current is low; when the potential gradient is in the range of 0.5 mv/m to 5.0 mv/m, the stray current is moderate; when the potential gradient is greater than 5.0 mv/m , the stray current level is high.The floating range of the potential gradient (EW) of the mid-slope, up-slope and down-slope is shown in Figure 3.In terms of the floating range, there are moderate stray currents in the east-west and north-south directions of the mid-slope.Therefore, stray current is an important factor affecting the corrosion of metal meshes on mid-slope and down-slope, especially on mid-slope.
Generally, soil redox potential (Eh) above 400 mV indicates the oxidizing ability, above 0-200 mV is medium reducing ability, and below 0 mV is large reducing ability.The lower the soil redox potential, the greater the corrosion ability of soil microorganisms to metals44.It is possible to predict the trend of soil microbial corrosion from the redox potential.The study found that the soil redox potential of the three slopes was greater than 500 mv, and the corrosion level was very small.It shows that the soil ventilation condition of slope land is good, which is not conducive to the corrosion of anaerobic microorganisms in the soil.
Previous studies have found that the impact of soil pH on soil erosion is obvious.With the fluctuation of pH value, the corrosion rate of metal materials is significantly affected.Soil pH is closely related to the area and the microorganisms in the soil45,46,47.Generally speaking, the effect of soil pH on the corrosion of metal materials in slightly alkaline soil is not obvious.The soils of the three railway slopes are all alkaline, so the effect of pH on the corrosion of the metal mesh is weak.
As can be seen from Table 3, the correlation analysis shows that the redox potential and the slope position are significantly positively correlated (R2 = 0.858), the corrosion potential and the potential gradient (SN) are significantly positively correlated (R2 = 0.755), and the redox potential and the potential gradient (SN) are significantly positively correlated (R2 = 0.755). There was a significant negative correlation between potential and pH (R2 = -0.724).The slope position was significantly positively correlated with the redox potential.This shows that there are differences in the microenvironment of different slope positions, and soil microorganisms are closely related to redox potential48, 49, 50.The redox potential was significantly negatively correlated with pH51,52.This relationship indicated that pH and Eh values ​​did not always change synchronously during the soil redox process, but had a negative linear relationship.Metal corrosion potential can represent the relative ability to gain and lose electrons.Although the corrosion potential was significantly positively correlated with the potential gradient (SN), the potential gradient may be caused by the easy loss of electrons by the metal.
Soil total soluble salt content is closely related to soil corrosivity.Generally speaking, the higher the soil salinity, the lower the soil resistivity, thus increasing the soil resistance.In soil electrolytes, not only the anions and varying ranges, but also the corrosion influences are mainly carbonates, chlorides and sulfates.In addition, total soluble salt content in soil indirectly affects corrosion through the influence of other factors, such as the effect of electrode potential in metals and soil oxygen solubility53.
Most of the soluble salt-dissociated ions in soil do not directly participate in electrochemical reactions, but affect metal corrosion through soil resistivity.The higher the soil salinity, the stronger the soil conductivity and the stronger the soil erosion.The soil salinity content of natural slopes is significantly higher than that of railway slopes, which may be due to the fact that natural slopes are rich in vegetation, which is conducive to soil and water conservation.Another reason may be that the natural slope has experienced mature soil formation (soil parent material formed by rock weathering), but the railway slope soil is composed of crushed stone fragments as the matrix of “artificial soil”, and has not undergone a sufficient soil formation process. Minerals not released.In addition, the salt ions in the deep soil of natural slopes rose through capillary action during surface evaporation and accumulated in the surface soil, resulting in an increase in the content of salt ions in the surface soil.The soil thickness of the railway slope is less than 20 cm, resulting in the inability of the topsoil to supplement the salt from the deep soil.
Positive ions (such as K+, Na+, Ca2+, Mg2+, Al3+, etc.) have little effect on soil corrosion, while anions play a significant role in the electrochemical process of corrosion and have a significant impact on metal corrosion.Cl− can accelerate the corrosion of the anode and is the most corrosive anion; the higher the Cl− content, the stronger the soil corrosion.SO42− not only promotes corrosion of steel, but also causes corrosion in some concrete materials54.Also corrodes iron.In a series of acid soil experiments, the rate of corrosion was found to be proportional to soil acidity55.Chloride and sulfate are the main components of soluble salts, which can directly accelerate the cavitation of metals.Studies have shown that the corrosion weight loss of carbon steel in alkaline soils is almost proportional to the addition of chloride and sulfate ions56,57.Lee et al. found that SO42- may hinder corrosion, but promote the development of corrosion pits that have already formed58.
According to the soil corrosiveness evaluation standard and test results, the chloride ion content in each slope soil sample was above 100 mg/kg, indicating strong soil corrosiveness.The sulfate ion content of both the uphill and downhill slopes was above 200 mg/kg and below 500 mg/kg, and the soil was moderately corroded.The content of sulfate ion in the middle slope is lower than 200mg/kg, and the soil corrosion is weak.When the soil medium contains a high concentration, it will participate in the reaction and produce corrosion scale on the surface of the metal electrode, thereby slowing down the corrosion reaction.As the concentration increases, the scale may break suddenly, thereby greatly accelerating the corrosion rate; as the concentration continues to increase, the corrosion scale covers the surface of the metal electrode, and the corrosion rate shows a slowing trend again59.The study found that the amount in the soil was lower and therefore had little effect on corrosion.
According to Table 4, the correlation between slope and soil anions showed that there was a significant positive correlation between slope and chloride ions (R2=0.836), and a significant positive correlation between slope and total soluble salts (R2=0.742).
This suggests that surface runoff and soil erosion may be responsible for the changes in total soluble salts in the soil.There was a significant positive correlation between total soluble salts and chloride ions, which may be because total soluble salts are the pool of chloride ions, and the content of total soluble salts determines the content of chloride ions in soil solutions.Therefore, we can know that the difference in slope may cause severe corrosion of the metal mesh part.
Organic matter, total nitrogen, available nitrogen, available phosphorus and available potassium are the basic nutrients of the soil, which affect the soil quality and the absorption of nutrients by the root system.Soil nutrients are an important factor affecting the microorganisms in soil, so it is worth studying whether there is a correlation between soil nutrients and metal corrosion.The Suiyu Railway was completed in 2003, which means that the artificial soil has only experienced 9 years of organic matter accumulation.Due to the particularity of artificial soil, it is necessary to have a good understanding of the nutrients in artificial soil.
The research shows that the organic matter content is the highest in the natural slope soil after the whole soil formation process.The low-slope soil organic matter content was the lowest.Due to the influence of weathering and surface runoff, soil nutrients will accumulate on the mid-slope and down-slope, forming a thick layer of humus.However, due to the small particles and poor stability of low-slope soil, organic matter is easily decomposed by microorganisms.The survey found that the mid-slope and down-slope vegetation coverage and diversity were high, but the homogeneity was low, which may lead to uneven distribution of surface nutrients.A thick layer of humus holds water and soil organisms are active.All of this accelerates the decomposition of organic matter in the soil.
The alkali-hydrolyzed nitrogen content of the up-slope, middle-slope and down-slope railways was higher than that of the natural slope, indicating that the organic nitrogen mineralization rate of the railway slope was significantly higher than that of the natural slope.The smaller the particles, the more unstable the soil structure, the easier it is for microorganisms to decompose the organic matter in the aggregates, and the greater the pool of mineralized organic nitrogen60,61.Consistent with the results of the 62 study, the content of small particle aggregates in the soil of railway slopes was significantly higher than that of natural slopes.Therefore, appropriate measures must be taken to increase the content of fertilizer, organic matter and nitrogen in the soil of the railway slope, and to improve the sustainable utilization of the soil.The waste of available phosphorus and available potassium caused by surface runoff accounted for 77.27% to 99.79% of the total loss of railway slope.Surface runoff may be the main driver of available nutrient loss in slope soils63,64,65.
As shown in Table 4, there was a significant positive correlation between slope position and available phosphorus (R2=0.948), and the correlation between slope position and available potassium was the same (R2=0.898).It shows that the slope position affects the content of available phosphorus and available potassium in the soil.
Gradient is an important factor affecting soil organic matter content and nitrogen enrichment66, and the smaller the gradient, the greater the enrichment rate.For soil nutrient enrichment, nutrient loss was weakened, and the effect of slope position on soil organic matter content and total nitrogen enrichment was not obvious.Different types and numbers of plants on different slopes have different organic acids secreted by plant roots.Organic acids are beneficial to the fixation of available phosphorus and available potassium in the soil.Therefore, there was a significant correlation between slope position and available phosphorus, and slope position and available potassium.
In order to clarify the relationship between soil nutrients and soil corrosion, it is necessary to analyze the correlation.As shown in Table 5, redox potential was significantly negatively correlated with available nitrogen (R2 = -0.845) and significantly positively correlated with available phosphorus (R2 = 0.842) and available potassium (R2 = 0.980).The redox potential reflects the quality of redox, which is usually affected by some physical and chemical properties of the soil, and then affects a series of properties of the soil.Therefore, it is an important factor in determining the direction of soil nutrient transformation67.Different redox qualities may result in different states and availability of nutritional factors.Therefore, the redox potential has a significant correlation with available nitrogen, available phosphorus and available potassium.
In addition to metal properties, corrosion potential is also related to soil properties.Corrosion potential was significantly negatively correlated with organic matter, indicating that organic matter had a significant effect on corrosion potential.In addition, organic matter was also significantly negatively correlated with potential gradient (SN) (R2=-0.713) and sulfate ion (R2=-0.671), indicating that organic matter content also affects potential gradient (SN) and sulfate ion..There was a significant negative correlation between soil pH and available potassium (R2 = -0.728).
Available nitrogen was significantly negatively correlated with total soluble salts and chloride ions, and available phosphorus and available potassium were significantly positively correlated with total soluble salts and chloride ions.This indicated that available nutrient content significantly affected the amount of total soluble salts and chloride ions in soil, and anions in soil were not conducive to the accumulation and supply of available nutrients.Total nitrogen was significantly negatively correlated with sulfate ion, and significantly positively correlated with bicarbonate, indicating that total nitrogen had an effect on the content of sulfate and bicarbonate.Plants have little demand for sulfate ions and bicarbonate ions, so most of them are free in the soil or absorbed by soil colloids.Bicarbonate ions favor the accumulation of nitrogen in the soil, and sulfate ions reduce the availability of nitrogen in the soil.Therefore, appropriately increasing the content of available nitrogen and humus in soil is beneficial to reduce soil corrosivity.
Soil is a system with complex composition and properties. Soil corrosivity is the result of the synergistic action of many factors. Therefore, a comprehensive evaluation method is generally used to evaluate soil corrosivity.With reference to the “Code for Geotechnical Engineering Investigation” (GB50021-94) and the test methods of China Soil Corrosion Test Network, the soil corrosion grade can be comprehensively evaluated according to the following standards: (1) The evaluation is weak corrosion, if only weak corrosion , there is no moderate corrosion or strong corrosion; (2) if there is no strong corrosion, it is evaluated as moderate corrosion; (3) if there is one or two places of strong corrosion, it is evaluated as strong corrosion; (4) if there are 3 or more places of strong corrosion, it is evaluated as strong corrosion for severe corrosion.
According to soil resistivity, redox potential, water content, salt content, pH value, and Cl- and SO42- content, the corrosion grades of soil samples at various slopes were comprehensively evaluated.The research results show that the soils on all slopes are highly corrosive.
Corrosion potential is an important factor affecting the corrosion of slope protection net.The corrosion potentials of the three slopes are all lower than -200 mv, which has the greatest impact on the corrosion of the uphill metal mesh.Potential gradient can be used to judge the magnitude of stray current in soil.Stray current is an important factor affecting the corrosion of metal mesh on middle slopes and uphill slopes, especially on middle slopes.The total soluble salt content in the soils of the upper, middle and lower slopes was all above 500 mg/kg, and the corrosion effect on the slope protection net was moderate.Soil water content is an important factor affecting the corrosion of metal meshes on mid-slope and down-slope, and has a greater impact on the corrosion of slope protection meshes.Nutrients are most abundant in mid-slope soil, indicating that there are frequent microbial activities and rapid plant growth.
The research shows that corrosion potential, potential gradient, total soluble salt content and water content are the main factors affecting soil corrosion on the three slopes, and the soil corrosiveness is evaluated as strong.The corrosion of the slope protection network is the most serious at the middle slope, which provides a reference for the anti-corrosion design of the railway slope protection network.Appropriate addition of available nitrogen and organic fertilizer is beneficial to reduce soil corrosion, facilitate plant growth, and finally stabilize the slope.
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