Ecological Disaster Mechanism And Function Improvement For Open-pit Mine Dump In Severe Cold Area

There are abundant coal resources in the alpine steppe area of eastern Inner Mongolia.The large-scale dump formed by large-scale open-pit mining reshapes the micro geomorphic unit in the area and aggravates the deterioration of the ecological environment of the mining area.Restoring and improving the ecological function of open-pit dump is an important premise to ensure the sustainable development of mineral resources and protect the ecological environment of mining area.Therefore,it is of great significance to study the ecological function improvement factors of dump under the disturbance of open-pit mining in severe cold area,and actively explore the ecological function improvement methods and measures of large dump under extreme environment,to ensure the green mining of mines and the construction of ecological civilization of mines in China.The thesis takes the Baorixile coal mine with fragile ecological environment as the object,and aims at the problems that affect the ecological function of the large-scale dumping site formed by mining,such as poor geological stability,low water and soil resource conservation ability,and poor self-sustainment of rebuilding plant communities.Using time-series remote sensing,UAV remote sensing,ground monitoring and other technologies,construct a multi-source collaborative monitoring technology system for ecological functions of large dumping yards in high-cold mining areas under complex conditions,and develop the elements of large dumping yards' ecological functions from multiple angles and multiple scales Time series monitoring,and in-depth research on the methods of early diagnosis and identification of geological disasters in dumps,as well as the process and cause mechanism of soil erosion changes,constructed an ecological function evaluation model,and explored strategies and models for improving the ecological functions of large dumps.It provides a scientific and effective method for the restoration and management of the ecological environment of the large dumping site in the alpine mining area.The main results are:(1)Through multi-source coordinated monitoring such as spaceborne remote sensing,UAV remote sensing,and ground surveys,it is found that there are three main problems affecting ecological functions in large-scale dumps in high-cold mining areas:(?)The overall situation is affected by uneven settlement,shallow landslides,slope creep,Poor geological stability caused by various forms of slope damage such as ground fissures,freeze-thaw damage,etc.;(?)Turbulent surface runoff and water and soil resource retention capacity caused by various forms of erosion and damage such as wind,hydraulic,freeze-thaw,and gravity Low;(?)The low vegetation species diversity,simple structure,and slow forward succession speed in the ecological restoration area make it difficult for the rebuilt plant community to sustain itself.(2)Using the time series Sentinel-1 image as the data source,long time series,large area,and high-precision deformation monitoring of the study area based on SBAS InSAR technology and amplitude tracking technology found that the study area generally has non-uniform deformation,which has accumulated vertical in the past three years.The maximum amount of deformation is 298 mm,and it increases with the increase of the dumping height.Through the constructed dynamic evaluation system for the potential disasters of the dumps,the potential geological hazard areas concentrated on the upper part of the slope were identified,and various degrees of shallow landslides,ground fissures,slope creeping,ground subsidence and uneven settlement were found.A form of slope failure.The geotechnical nature of the dump site,the local slope structure,the overall landform structure and the erosion and weathering environment affect the stability of the slope.Especially under the special conditions of alternating cold and drought and freeze-thaw cycles,the slope in the study area is subject to internal freezing heave,slope freeze-thaw creep and freeze-thaw landslide have serious impacts.(3)Multi-source collaborative monitoring technology is used to monitor the compound soil erosion status in the study area in time series,combined with geomorphology,hydrology,meteorology and other data,to study the various erosion effects of wind,hydraulic,freeze-thaw and gravity factors on the dump.Based on the time series decomposition,the spatial distribution characteristics and erosion degree of various erosions in the study area are obtained.Based on the geotechnical and chemical parameters of the study area,a profile erosion model was constructed.Numerical simulations were used to study the soil flow erosion in slope hydraulic erosion under different rainfall intensities and different slope conditions.The results showed that the slope soil under different conditions The degree and maintenance time of midstream erosion are different.Erosion begins to form at the beginning of rainfall,and the flow velocity increases with the increase of rainfall intensity or slope.The unique climatic characteristics of the study area have led to the occurrence of freeze-thaw erosion.Erosion transport mainly occurs on the slopes on both sides of the erosion ditch.The area subject to freeze-thaw erosion accounts for more than 80% of the total area.The degree of erosion increases with the increase of the slope,and the length of the slope increases.The factor increases and decreases,and it increases with the increase in daily radiation.Under the effect of frost heave,the upper soil of the slopes on both sides of the erosion ditch is easy to freeze and crack,forming a wedge-shaped failure surface.Under the action of gravity,the erosion phenomenon is formed in the form of flakes,causing the erosion ditch to continue to develop on both sides.(4)Using surface sampling survey and handheld hyperspectral camera to acquire and establish a spectral library of superior potential plant species in the study area,use UAV hyperspectral remote sensing technology to obtain vegetation spectral images in the study area,and use the spectral angle classification method to obtain The refined classification of plants in the study area,combined with the advantages of remote sensing spatial mapping,completed the mapping of species diversity in the study area.It is found that plant growth varies greatly under different site conditions in the study area.Slope,slope position and reclamation period are the main factors affecting plant growth and succession.Vegetation coverage and species diversity increase with the extension of the restoration period,and gradually succeed from an entirely artificial plant community to a natural community dominated by native species.(5)Using support vector machine,artificial neural network,logistic regression model and classification regression tree model,the ecological function evaluation model of the study area was constructed respectively.After accuracy statistical analysis and subject acceptance curve analysis,it is shown that the non-linear ecological function evaluation model of support vector machine has the highest accuracy.Vegetation status,reclamation period,terrain deformation rate and slope are the main factors affecting ecological functions.(6)According to the mechanism and manifestation of "geology-soil-vegetation" on the ecological function of the study area,the promotion criteria of "long-term planning,key management,overall restoration",and "monitoring,evaluation,planning,management and feedback" are proposed.Implementation framework,as well as implementation measures guaranteed by ecological function problem diagnosis technology,distributed water conservation and erosion control technology,and species allocation technology.A plan for improving the ecological function of the dump in the alpine mining area is proposed with the goal of establishing a stable ecosystem,and comprehensive consideration of slope stability,water and soil resource utilization,and plant community stability.The constructed model for improving the ecological function of the dump in the high-cold mining area has answered and demonstrated several basic issues,such as the control of loose slope geological stability,the maintenance and reconstruction of scarce water and soil resources,the maintenance of plant communities and the acceleration of forward succession,enrichment and development The theoretical method and practical basis for the stable improvement of the ecological function of the dump in the alpine mining area are presented.