Determination on Rational Width of Coal Pillar in Strip Mining Face

In order to fully mine the coal resources under buildings, railways and water bodies, to improve the coal mining rate and to minimize the underground mi ning affected to the surface subsidence, a strip mining method under the surface buildings, railways and water bodies was analyzed. The FLAC3Dnumerical simulation and theoretical calculation combined method were applied to systematically study the vertical stress distribution of the surrounding rock and the surface subsidence law when the mining width was 20 m and the coal pillar width was 10, 20, 30 and 40 m individually. The study conclusions showed that when the coal pillar width was about 1.5 times of the mining width, the max surface subsidence value would be 0.042 m and the coal mining rate mining under the surface buildings, railways and water bo dies was 40%.