Based on the analysis of the influencing factors of top coal caving forms and physical mechanics characteristics of caving top coal, the methods of controlling top coal caving have .

Based on the the fully-mechanized top-coal caving mining of 8~# coal bed in Kangjiatan coal mine,the probability of the gas explosion induced by the impact-friction sparks during roof collapse was studied with the special designed experimental instruments.

The analytical reason of the subsidence is that old working roof collapse strengthen the vertical morenent of underground water between coal-series formation and Quaternary loose formation, the strong drain of coal mining in the area intonsify the erosion and transporting action of underground water, the Quaternary carity forms and the earthquake cause to ha.

For roof collapse control of the belt-conveying-roadway of No.

Roof pressure,structure,water volume,support deformation that are related to the roof caving mechanism are analyzed.

In order to solve the problem of roof caving of orebody in deep broken zone of Kangjiawan mine so as to realize safety mining,we performed the mechanical experiment of rocks,compared and numerically simulated the roof controlling measures,tested the mechanical parameters of rocks,analyzed and classified caving phenomenon.

Based on field observation and simulation tests,the characteristic of slipping-fall ofimmediate roof for joint rock mass is clarified,and a corresponding mechanical model is established in this paper.