The paper analyzes inclined laid cantilever beam induced by cracks for sublevel caving mining face with the help of mechanial analysis methods,and discusses the effect regularilies of crack′s trend and beam section shape on top coal breaking.

The orientational coring technique,with its main purpose of detecting fracture azimuth, is an important approach to study fracture system, and it is also a kind of supplementary for other fracture detecting techniques.

To obtain such parameters as the fracture azimuth and dimension of hydraulic fracturing accurately is significant to the development of Changqing low permeability reservoirs.