In order to get the deformation and seepage law of protected coal seam in the process of mining

the thesis has carried deformation and seepage experimental research of coal sample under the effect of stress.Taking Hongyang Third Mine protection layer mining as engineering background

load-unload path of lower protected coal seam is got in the process of protective coal seam mining by numerical simulation.On the basis of this load-unload path

protected coal sample load-unload experiment is carried out.Finally

the stress-strain curve and the stress-permeability curve are obtained.The research results show that during the loading and unloading process

the axial deformation varies from linearity to nonlinearity

and the unloading process to strain failed to return to the initial value;Hoop strain changes with added unloading performance for nonlinear.The same stress value corresponding to permeability change rule is as follows:first unloading phase permeability is lower than first loading phase permeability.First loading phase permeability is lower than secondary loading phase permeability.