ABSTRACT
This paper briefly describes the new researches of classification of immediate roof, main roof and floor at coalface after its stability, weighting intensity and resistance against supports penetration respectively, as well as the optimal selection of structure and load density of powered supports including the cases of hard roof and hardly caved roof, in which series formulae based on the regression analysis and theory of plant and principle of roof-soften are given. These are important for improving the ground control and safety and economic effect during mining.
