Evaluation of Impermeability of Coal Seam Floor when Mining with Water Pressure

摘要

Impermeability of coal seam floor is one of the most important factors for a safe coal mining with water pressure. Based on geologic data analysis，field observation and laboratory testing and analyzing，a systematic study was done to the geological conditions of Taiyuan Formation(C3t) coal seam mining under hydraulic pressure in Shaqu Coal Mine. Through the study on lithology and sedimentary facies，Fengfeng formation(O2f) was divided into 4 segments and could be regarded as relative aquiclude. The impermeability of the aquiclude was further investigated by means of slice observation, mercury penetration and servo experiment. The rock voidage is mainly ultramicropore and micropore. The throat diameter is very small, so is the permeability value under complete stress-strain permeability test. Finally the conclusion was put forward that Fengfeng Formation can be regarded as a relative water-resisting layer, which will be favorable to the safe mining of Shaqu Coal Mine.