Field measurement study on deformation and destruction of "three-soft" coal seam floor of Chaohua Coal Mine

The depth of deformation and destruction and the zone of variation in front of mining working face under the mining effect of the "three-soft" coal seam floor of Chaohua Coal Mine in Zhengzhou mining area are systematically studied by use of the field strain measurement. Thick soft coal seam and soft floor have a buffer action on the stress and deformation under the normal condition, and the vertical stress is much greater than the horizontal stress because of the influence of stress concentration. The middle section of limestone has an important controlling function to the stress distribution and deformation and destruction. It provides the basis for the seepage prevention and treatment of floor water for mining deep coal in the west of Henan Province.