Studying on Mining Cracks Closure Characters of Overburden under Thickly Loess Layer and It's Application

In order to scientific evaluated base stability that old goaf to new village site,and then the mining cracks closure characters after coal mining 16a under thickly loess overburden layer were studied by the following methods,which included that drilling fluid leakage observation,colourful TV observation and theoretical calculation method and so on,the results showed that after many years movement and deformation,separation,cavity were not found in overburden above goaf area,and mining fractures already closure,and also obviously fractures were not found above working face pillar,overburden fractures development was controlled effectively by isolation coal pillar,the characters of mining crack width and goaf distance appeared as far small and near large,overburden crack width was large as the distance to goaf was small,and overburden cracks already closure as the distance to goaf was large,and water conducted zone decreased about 21%,the influence that buildings additional load to old goaf distribution,the second compress of residual interspace and surface residual deformation to new village site all small,and the base also stability.