Analysis on rupture of hard and massive overlying strata in fully-mechanized sublevel caving face

According to the characteristics of sediment rock and the movement of hard and massive overlying strata, using the mechanical rules of movement based on the mechanical model of fixed beam with gravity taken into account, the judgment curves of movement modes of overlying strata were worked out and their applications were explained. Using the judgment curves and the thickness of key strata decided from the parameters of drilling hole, the movement modes of key strata were judged and the theoretical basis for controlling the hard and massive strata were analyzed in mining engineering was provided. The factors influencing the movement modes of hard and massive overlying strata and the delamination movement of hard and massive overlying strata were explained as ubiquitous because of the characteristics of hard and massive strata with interbedding. The suggested mechanical judgment model had been tested by field experiments, and compared with the simple uniform stress method usually used, and it was shown to be useful for the prediction of the initial rupture and span of the main roof of the hard and massive strata.