Study on Mine Strata Pressure Behavior Law of Coal Mining Face in Ultra Contiguous seam with Shallow Depth

According to the unclear mine strata pressure behavior,short periodical roof weighting step distance and other problems occurred in No.12102 coal mining of Shigetai Mine in Shendong Mining Area,the site measurement,theoretical analysis and physical simulation method were applied to study the mine strata pressure behavior features and periodical roof weighting law of the coal mining face in the ultra contiguous seam with shallow depth.The results showed that the periodical roof weighting step distance of the coal mining face in seam under mining goaf was 23 m,was 2.1 times higher than the coal mining face in above seam and the sustainable length of the periodical roof weighting would be reduced by 0.8~1.6 m.The main causes of the phenomenon occurred was the mine strata pressure behavior of the coal mining face in the below seam affected by the rotary movement of the main key stratum in the overburden.Due to the broken block of the main key stratum was long and the distance to the below seam was far,the small angle rotary of the broken block in the main key stratum could have the support of the falling rocks in the mining goaf and thus a phenomenon with a longer periodical roof weighting step distance and a shorter roof weighting sustainable length of the coal mining face would be occurred.