Influence Of Coal Mining Subsidence On Properties Of Sandy Soil In Erdos

Shendong digging, as an important coal productive base for our country in Erdos, its environment is destroyed greatly by Coal resource mining. Especially to soil, as a vital part of environment, is transformed in Properties. As a basic research work for land reclamation, in this paper through field investigation, observation on the spot and lab analysis, the variation of the sandy soil physical and chemical properties was researched by the numbers in subsidence area, including of different soil layer, slope location, subsidence time and degree. In addition to, the influence degree was comprehensively appraised using principal component analysis method. The results showed as following:(1) In the level direction, some properties value of the soil decreased due to coal mining subsidence, including of bulk density, field water-holding capacity, wilting coefficient and available water capacity, rigidity and containing water, but soil extent of porosity and saturation conduction had incresed after subsiding. The subsidence extent became larger, soil bulk density, rigidity and containing water were lower and soil extent of porosity and saturation conduction were higher. In the vertical direction, the depth is deeper, soil extent of porosity and saturation conduction became larger, but other phesical indexes were decreased. Comparatively the two sides of the same fissure, the rigidity of the higher side is larger than that of the lower side, but containing water is on the contrary.(2) Comparatively, in the subsidence area the filtering depth was decreased when soil gained lesser water. On the contrary, there were great pertinence between the filtering depth and the subsidence degree on the condition of soil moisture supplied adequately.The filtering depth after subsidence was increased and the lower side is larger than that of the higher side when soil can get a lot of water.(3) There were no distinct discrepancy for the soil nutrient in between control area and the subsidence area, but the space distributing had difference. The nutrients which included the soil organic matter content, nitrogen, phosphorus, and kalium were reduced in the subsidence area, of which the middle slope was lower than the intervale, of which the fissure was less than no fissure, and of which 1a was higher than 2a. There were a trend which the surface N,P,K were transferred toward underlay in different layers.The average PH value was decreased due to subsidence, the fissure was lower than no fissure, the middle slope was higher than the intervale, and 2a was lower than 1a. The surface PH value in subsidence area was higher than that of control area, but underlayer was lower than that of control area. This showed hydrogen hydroniumes had been transferred from surface to underlayer.(4) Using the principal component analysis method to comprehensive evaluate the influence degree of the subsidence, the results showed that the influence of soil physical property would be weaken with the lapse of subsidence time.At the same time, the influence would be transferred from underlayer to surface. In the first instance the underlayer soil was infuenced worse than the soil superstratum was by the subsidence. The subsidence had been evoluted gradually from underground to surface since coal was mined. The soil superstratum affected reached most after a period of time.Compared with soil physical property, the changes of soil chmical property were lagged, and soil nutrient loss would be larger with the time before the subsidence was steady.