Effect Of Freeze-thaw On Soil Erodibility Of Dump In Open-pit Mine

Freezing-thawing is one of the important factors that reduce soil erodibility in the dump of open-pit mine.The loess Plateau in northwest China is in the seasonal frozen soil region,and the influence of freezing-thawing has intensified the severity of soil erosion.It is of great significance to enhance the corrosion resistance of soil in the dump of open-pit mine for ecological restoration and regional ecological sustainable development.By analyzing the shear strength,the average weight diameter,the average geometric diameter,the soil erodibility factor K value and the aggregate content R>0.2mm of four kinds of soils under freezing and thawing,the influence of freezing and thawing on soil erodibility was revealed in this dissertation.Based on the experimental data and theoretical analysis,the deterioration trend and reasons of the shear strength of the loess and the planted soil in the study area affected by freezing and thawing were revealed.The mathematical relationship between shear strength of loess and water content and freeze-thaw cycles is summarized by data arrangement and induction.The average weight diameter,average geometric diameter,soil erodibility factor K value and aggregate content R>0.2mm were measured by LB method under three different disturbance conditions,such as rainstorm erosion,light rain infiltration and artificial mechanical erosion.The results show that the weight diameter,average geometric diameter and aggregate content R>0.2mm decrease with the increase of freezing-thawing cycles,and the soil erodibility factor K increases with the increase of freezing-thawing cycles,and tends to be stable at 6-8 cycles.The best results were obtained of vegetation soil with robinia fruticosa under simulated rainstorm and mechanical erosion conditions,and of vegetation soil with alfalfa under simulated light rain erosion conditions.The vegetation types and soil erosion status in the study area of the mining area were investigated and studied,and the regional reclamation plan and specific vegetation-engineering restoration measures were formulated according to the development plan of the mining area.To the dump area,engineering measures were adopted to micro-reshape the landform to reduce soil erosion and enhance soil erosion resistance.Numerical simulation software was used to simulate and calculate the remolded landform,analyze the distribution and stability of water level,and select vegetation species based on the problems that are prone to occur in different areas of the dump,combined with the characteristics of different vegetation.In the cultivated area,the topsoil was improved by adding fly ash and sludge compost,and the alfalfa vegetation was planted for nitrogen fixation.It is reasonable to adopt vegetation-engineering restoration technology according to local conditions.There are 46 figures,16 tables and 84 references in this dissertation.