The horizontal section top coal caving in steep seam is different from the gently inclined seam.

The mine adopts a coal demolish feebleization technique beforehand to implement top coal caving.

Based on the physical phenomenon that the amount of the gamma ray radiation in rock is different from the amount of the gamma ray radiation in coal,the paper puts forward the method for coal rock detection in top coal caving.

Based on conditions of Gengcuen coal mining (二 3)coal with sub-level caving mining.

The ground behavior regularity of caving method coal face on “soft seam with soft surounding”and extremely unstable seam and the optimization of support patterns;

The numerical analysis on the stress distribution and the displacement of the top coal in sublevel caving mining;

Research on the possibility of enhancing the upper extraction limit with sublevel caving method under the highly thick hydrous ravelly stratum;

Study of optimization on the dilution ratio of roof coal in sublevel caving mining;

In this paper,the characteristics of deformation and failure in the overlying strata movement, caused by fully-mechnized sublevel caving mining of 63_上 10 face by using the new eqiuprnent with two pipelines for water injection system, and compared with the observing results of other mining methods, are studied according to fracture mechanies theory.