Hydrological Processes Of Soil Cracks In Coal Mine Dump Under Different Backfilling Techniques

Coal mining is very likely to cause a series of environmental and ecological problems such as loss of vegetation,surface subsidence,surface collapse and land occupation,of which opencast mining is the most serious.As a giant pagoda-shaped artificial loose pile,the drainage site is prone to soil cracks,exacerbating soil erosion and causing soil erosion disasters such as landslides,slides,landslides and debris flows.Especially under extreme rainstorm conditions,water stored in the cracks and surface runoff generated in the surrounding areas,along the soil cracks to reach the interior of the soil,is very likely to affect the stability of the overall geomorphic unit of the drainage field,resulting in a series of hydrological processes such as overall full storage and seepage.Based on field sampling,soil crack backfill simulation,artificial rainfall simulation,indoor evaporation simulation and other experimental analysis methods,the hydrological processes of soil cracks in the drainage field under different backfill treatments with different rainfall intensities are studied in order to provide a theoretical basis for soil crack management in the drainage field.The main research contents and results are as follows.(1)The characteristics of flow production and sand production under different backfilling techniques of soil cracks in the discharge field.Based on the west drainage field of Fuxin Haizhou opencast coal mine,three factors(width-to-depth ratio,rainfall intensity,backfilling technology)were designed to simulate the backfilling of soil cracks at three levels(width-to-depth ratio: 0.250,0.3125,0.375;rainfall intensity: 60mm/h,90mm/h,120mm/h;backfilling technology: backfilling treatment 1 with a backfilling ratio of 1:1,backfilling The orthogonal tests were carried out to simulate the soil erosion process in the drainage field under different fracture conditions and to analyse the flow production and sand production process.The flow production characteristics under each condition basically show an increasing trend,with a slow increase and an up and down fluctuation in the data;the sand production characteristics basically show a decreasing trend,with a slow decrease and an up and down fluctuation in the data.Under the three groups of backfill treatments with different rainfall intensities,and combining the water and sand reduction benefits of each group of cracks,the runoff volume and sand content were the lowest when the backfill was 1kg of soil mixed with 100 g of rice straw,1kg of soil mixed with 250 g of maize cob and 1kg of soil mixed with 250 g of polylactic acid.(2)Evaporation characteristics of soil cracks in the discharge field under different backfill techniques.Based on the west drainage field of the Fuxin Haizhou opencast coal mine as the research object,a two-factor(width-to-depth ratio and backfill technology)three-level(width-to-depth ratio and backfill technology are consistent with the design of the soil crack backfill simulation test)indoor simulated evaporation test was designed to study the effects of different backfill materials on soil water evaporation under different backfill crack conditions,and to analyse the daily evaporation,cumulative evaporation,soil water content and evaporation water loss ratio.The trends of daily and cumulative evaporation of soil moisture under different backfilling treatments with different cracks were generally consistent with those of the control group without cracks.Combining the characteristics of flow and sand production and evapotranspiration of the different backfill treatments,the backfill treatment 1 with 1 kg of soil mixed with 100 g of rice straw,1 kg of soil mixed with 250 g of maize cob and 1 kg of soil mixed with 250 g of polylactic acid had better water retention and soil conservation capacity.This paper has 32 figures,2 tables and 130 references.