The urgent need for the control of surface subsidence caused by longwall enal mining in densely populated areas of China has led to a feasibility study on the effectiveness of longwall goaf cemented hack fill. The study u focussed on exploring the potential of longwall goaf cemented backfill practice for surface subsidence control. Specific backfill geometry was designed in view of the characteristics of the longwall coal mining system. Laboratory physical simulated tests were carried out with different backfill material properties and pack size. The tests achieved a marked reduction in surface subsidence by the use of goaf cemented backfill. The system has been shown to he effective in laboratory tests._x000D_
the challenge now is to overcome the engineering problems to put it into Practice