CAO Jian , CHEN Yi
(Mining and Coal School , Inner Mongolia University of Science and Technology , Baotou 014010 , China)
Abstract : Shendong coalfield mainly contains shallow and close coal seams . Most of the upper coal seams of the mine have been ex- ploited and the mining of the lower coal seams is started. The arrangement of coal pillars in the upper and lower coal seam sections will directly affect the subsidence of overburden and surface and the development of cracks and fissures , which will further deteriorate the o- riginally fragile ecological environment. With the 2-2 coal and 3-1 coal mining in Shigetai Coal Mine as engineering background , the reasonable offset distance of section coal pillars is studied combeind with physical and numerical simulation. The results show that when the offset distance of the coal pillars is less than 40 meters , the fracture fields of the coal pillars in the upper and lower sections are su- perimposed , and the coal pillars in the upper sections settle . When the offset distance of the coal pillars is 40 meter , the fracture fields of the coal pillars in the upper and lower sections are separated , and the coal pillars in the upper sections reach full settlement. When the offset distance between coal pillars is more than 40 meters , the development of surface subsidence and overburden fractures do not change much. Therefore , the reasonable coal pillar offset distance of 2-2 coal and 3-1 coal mining in Shigetai Coal Mine should be more than 40 meters .
Key words : shallow and close coal seam ; repeated mining; section coal pillar; reasonable offset