| Traditional slope protection methods are difficult to meet people’s increasing demand for a beautiful highway environment.Vegetation slope protection can reduce the negative impact on the ecological environment caused by highway construction while controlling slope erosion.External-soil spray seeding(ESSS),a technique widely used to restore cut slopes.For the steepness,lithology and water storage conditions,it is hard to guarantee the speed and persistence of vegetation restoration on cut slopes.Moreover,High-cut slopes are more prone to excessive slope erosion under rainfall conditions.Based on actual engineering,this paper studied the vegetation restoration and slope erosion characteristics of cut slopes restored by ESSS,through on-site investigation,experimental testing,model establishment and analysis,the results of this study can provide scientific evidence for the promotion of ESSS.The main research work and results of this paper are as follows:(1)Through an 18-year investigation,the vegetation restoration characteristics of the cut slopes restored by ESSS were studied.After ESSS,the vegetation coverage on the slope reaches48%～61%within 3 months,and the peak coverage was stabled at around 95%and 88%after the second year.The speed and persistence of vegetation restoration on the slope are good.Coverage and biomass increased rapidly from April to July.In the early stage of establishment,the community was mainly composed of initial spraying species such as Bermudagrass,which was later replaced by native plants,forming a new community dominated by grasses such as Dicranopteris in the 18th year,and the diversity and stability of the community were significantly improved.The introduction of fast-growing species such as bermudagrass and functional species such as Tephrosia can significantly reduce the erosion of slopes in the early stage and promote the establishment of native plants.(2)By analyzing the results of rainfall experiment,the erosion characteristics of the slope were studied.When the rainfall intensity was less than 157.8 mm/h,the main water erosion processes of the slope were splash erosion,sheet erosion and rill erosion.The soil erosion modulus was linearly positively correlated with the rainfall intensity(R~2=0.996),when the rainfall intensity was 96 mm/h and the vegetation coverage was 29%,the soil erosion modulus was reduced by 82.9%compared with that when the slope was bare.Slope erosion mainly occurred in the rainy season two years after ESSS,and the integrity of the slope remained good in the 18th year.In the long term,the content of soil organic matter can meet the needs of vegetation growth,and the p H level of the soil was around 4.6,which was suitable for the growth of Dicranopteris.(3)Based on the water erosion prediction model,the erosion protective effect of vegetation was analyzed.Vegetation in the slope has a significant effect on soil erosion control.The reduction rate of soil erosion from the second anniversary is higher than 90%,and the long-term soil conservation effect was good.The spraying month has obvious influence on the erosion protective effect of vegetation.From March to May and August to September each year,it is more suitable for the construction of ESSS.If one chooses June and July for construction,it would be very necessary to pay attention to temporary protection measures such as non-woven fabrics. |
