Study on influence of surface ecological environment caused by middle deep coal mining and the ways of restoration

With the development of Jurassic Coalfield in Northern Shaanxi,the middle deep buried coal seam mining mines has become the focus at present and in the future.However,at present,the surface ecological environment damage caused by middle and deep coal seam mining is not clear,and there is a lack of corresponding ecological environment repair and promotion research.Therefore,the typical coal mine mining middle deep coal seam in Yushen Coal Mining Area were taken as the research objects,the method of field investigation and theoretical analysis were adopted to study the influence of middle and deep coal seam on the surface ecological environment.The results show that:The overall characteristics of surface cracks induced by middle and deep coal seam mining are weak,and the damage to the surface is small,and the cracks in working face expand forward in the shape of “C” with the mining,and have the unimodal activity characteristic of “opening first and then closing”,and the boundary cracks have the single trend activity characteristic of “only opening and not matching”.The development depth of surface cracks is less than 2.5 m,and the difference of depth per unit length is in 5～142 cm/m.The surface crack is the main way to affect the surface ecological environment,and the infiltration of near-surface water resources was increased by surface cracks.It also change the distribution characteristics of soil moisture that reducing the water content of 20 cm in the shallow soil layer,increasing the soil moisture in the depth of 40～60 cm.Meanwhile,the organic matter and the pH values in the shallow surface soil layer were increased by surface cracks.The wide cracks caused the vegetation roots to break and wither and die,while the short cracks will increase the richness of the gramineous plant Lemus chinensis.The ecological environment restoration and promotion system framework included “one evaluation and two predictions” before mining,“one pursuit and one reduction” during mining,and “three determinations and one mention” after mining was put forward,and its connotation,contents and technical approaches were expounded.Under the guidance of the ecological environment restoration and promotion system,natural restoration was determined as the main way to restore the surface ecological environment caused by the middle and deep coal seam mining in Yushen Mining Area.Combined with the present situation of ecological environment in the middle of Yushen Mining Area,the ecological environment promotion ways of “wetland construction”,“ecological agriculture construction” and “ornamental garden construction” are put forward and their feasibility is discussed.The research results of this paper have reference value for mining damage reduction and ecological restoration and promotion of middle and deep coal seams.