Abstract:There are a large range of mined-our areas in under planning construction field. They have been reinforcement by using grouting method. Althoug a lot of water has been filled in mined areas, multi-layers mined-out areas still occurred. By using grouting method as first thin and thick after, changing diameter settings of the grouting holes, first grouting outside and then grouting insdie, and dense outside and sparse inside, grouting effect can be improved.