Abstract: It was difficult to accurately assess the risk of powered support jammed in upper exploitation limitation-heightened working face due to the complexity and abruptness of powered support jammed accidents. Through system analysis of the effect factors and risk indexes caused by the geological and mining technology conditions of powered support jammed danger, a classification forecast method of powered support jammed in raise working face has been proposed with comprehensive index method, and the comprehensive index of powered support jammed has been determined in this paper. The hazard degree of powered support jammed can be divided into four classifications: no risk, weak risk, medium risk and strong risk; the corresponding preventing measures have been proposed according to hazard degree and main effect factors. According to the application results of this method in some engineering practice, the evaluation results are basically consistent with the actual situation, which proves that the evaluation method can be used in powered support jammed prediction.

Key words: comprehensive index method, geological factors, mining technologic factors, upper exploitation limitation-heightened working face, powered support jammed