| Exposed slopes in loess hilly and gully areas are prone to severe soil erosion,in this paper,Microbially Induced Calcite Precipitation(microbially induced calcite precipitation,MICP)technology was used to conduct the microbial solidification and vegetation restoration of loess slope,the growth and reproduction rule of Sporosarcina pasteurii and the composition and microstructure of microbial solidification loess was analyzed,the mechanism of MICP technology for solidification of loess slopes was revealed,the methods of microbial solidification and vegetation restoration of loess slope were established,the control effect of microbial solidification and vegetation restoration on soil erosion of loess slope was studied,The main research results and conclusions are as follows:(1)After solidification treatment of outdoor loess slopes using MICP technology,a certain thickness of solidification layer is generated on the slope surface,through XRD analysis shows that the calcium carbonate crystals generated in the slope solidified layer are of calcite type,the main form is a rhombic hexahedron,with a crystal diameter of approximately 4μm-8μm,the white calcite crystal generated after solidification cemented the adjacent loose soil particles together,thus improving the integrity and overall strength of the slope.(2)After solidifying the loess slope for vegetation restoration,calculate the growth status of vegetation in each area of the 25°and 35°loess slope,the survival rate of vegetation in each solidified area of the loess slope is higher than that in each control group area,and in each area where water retaining agent is added after solidification has the highest survival rate of vegetation,the maximum growth and variation of height and diameter of Amorpha fruticosa,and the best growth status of Ophiopogon japonicus and Amorpha fruticosa.(3)MICP technology was used to solidify loess with different density,the permeability of solidification loess reduces with the increase of solidification treatment times,and the smaller the density of the soil mass,the greater the impact of solidification treatment on its permeability,when the number of solidification treatments reaches 5 or more,the permeability of soil mass with different densities tends to stabilize.After solidification treatment,for the loess with a density of 1.33g/cm~3,the water retention performance of solidified loess sample was increased,for the loess with a density of 1.53g/cm~3,the water retention rate of the solidified soil sample was lower than that of the undisturbed soil sample during 9d to 28d,and the water retention rate of the soil sample was the worst when it was solidified for 5 and 7 times.(4)Conducting indoor artificial simulated rainfall erosion tests after vegetation restoration on solidified loess slopes,the total sediment yield and sediment yield rate decrease with the increase of soil mass density and solidification treatment times,while the total runoff yield and runoff yield rate increase with the increase of soil mass density and solidification treatment times.When planting Ophiopogon japonicus on solidified loess slopes with different densities,the runoff and sediment yield rates on the slope were the smallest,while the total sediment yield on the slope decreased the most,which respectively decreased by 83.74%,84.50%,and 85.61%.(5)The use of MICP technology to solidify loess slopes and restore vegetation can effectively improve the erosion resistance of loess slopes,after solidification treatment of loess slopes,respectively planting Ophiopogon,Amorpha fruticosa and interplanting Ophiopogon and Amorpha fruticosaand,the slope can resist continuous erosion of rainfall intensity of 120mm/h for more than 1 hour when the number of solidification treatments reaches 5 or more times,among them,the solidified loess slope planted with Ophiopogon has the best erosion resistance performance. |
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