Effects Of Coal Mining Subsidence On Soil Physical Properties In Mu Us Sandy Land

Lijiata Coal Mine,as one of the wells and mines in the Dongsheng Coalfield of Shenfu,is located on the southeastern edge of the Mu Us Sandy Land.In recent years,large-scale underground mining has caused a large number of cracks and severe uneven settlement on the ground,and the ground plants have withered or died.Sandy land is in danger of activation.By measuring the physical properties of the soil around subsidence cracks with different subsidence depths and different widths,the impact of coal subsidence on soil physical properties and their spatial differentiation laws are clearly identified.The following conclusions are mainly drawn:(1)After the collapse,the soil bulk density becomes smaller,and with the increase of the crack width and subsidence depth,the soil bulk density gradually decreases.At a depth of 0-60 cm,the bulk density gradually increases with the increase of the soil depth,and the soil bulk density is around the subsidence.The influence is more significant in the range of-25 cm;with the increase of the width of the cracks and the depth of the subsidence,the soil porosity increases,and the soil porosity in the 0-60 cm soil layer increases,but it is not obvious.The measured plots showed a maximum.(2)After the subsidence,the soil water holding capacity decreases with the increase of the width of the crack and the depth of the subsidence.The depth of soil water holding capacity increases with the depth of the soil at 0-60 cm.The water holding capacity of the soil in the sample site 25 cm from the collapse was relatively low.The water holding capacity of the collapsed cracks with a width of 60-100 cm decreased by up to 4.03%,and the severe subsidence decreased by 6.15%compared with the control area.The amount of water increases with the increase of crack width and subsidence depth.The maximum water holding capacity gradually increases with the increase of soil depth at the depth of collapsed fractures with different widths of 0-60 cm.As the depth of the soil layer increases,it gradually decreases;the maximum water holding capacity of the soil shows a minimum value in the subsidence area,and there are no obvious fluctuations in the measured points in other places.(3)Compared with the control area,the soil moisture content in the subsidence area was significantly reduced,cracks with a width of 0-20 cm decreased by 0.15%,cracks with a width of 20-40 cm decreased by 0.6%,and cracks with a width of 40-60 cm decreased The cracks of 0.88%and the width of 60-100 cm decreased by 1.41%;the water content of lightly collapsed soil decreased by 0.46%,the water content of moderately collapsed soil decreased by 1.61%,and the water content of severely collapsed soil decreased by 1.99%.Under the depth of 0-60 cm soil layer,the soil water content of each soil layer is specifically expressed as:soil layer 0-10 cm<10-20 cm<20-40 cm<40-60 cm,within the range of 0-100 cm around the subsidence,The soil moisture content is small in the collapsed area and the measured sample area 25 cm away from the collapsed area,and the minimum value appears at the measured sampled area 25 cm away from the collapsed area.