Research of observed test on safety exploiting depth of mining under buildings;

Analysis of the mining failure regularity and safety mining of the weak and weathered composite roof;

The scientized mining technology includes efficient mechanized mining,green mining,safety mining,and mining with high exploitation rate while the scientized mining refers to the one which can realize the coal mining with the highest efficiency on the precondition.

Those provide basis for safety mining of coal floor.

The authors introduced the development of China's mining technology of fully-mechanized top-coal caving and clarified fully-mechanized top-coal caving as a productive and safe mining method.

We selected as the blasting indexes based on an analysis of the mechanism of rockburst: the mining depth,the ratio of maximal tangential stress and uniaxial compressive strength of the surrounding rocks,the ratio of uniaxial compressive strength and uniaxial tensile strength,and the elastic energy index.

In order to provide necessary technical parameters for the mining design and stope site management of the residual bauxite deposit,scientific calculation and discussion are made on the mining depth of the residual deposit according to the occurrence features of the residual bauxite deposit and the existing mining technology and the requirements for economic reasonableness of the mine.

In a mine,under different mining depth and thickness conditions,the displacement angle of stratum is not const,but complicated un-liner relations changing with mini.

The calculating principle and method of mining safe depth by loose coefficient have been probed.