For the outburst-dangerous potash levels strata the researches were conducted and the results were presented relating to the geomechanical modeling of the stressed and deformed massif condition around the roadway with gas nucleus (accumulation) in the floor. It is given the calculation model description and criteria of possible collapse of the roadway floor rocks including the condition when it is being mined. In order to prevent the sudden gas and dynamic phenomena, the forced rock massif degasification is recommended.