Study on cause classification method and support countermeasures of roof falling in coal drift

Based on about 200 roof falling accidents occurred in coal drift, the paper analyzed the mechanics properties and structure features objectively existed i n the surrounding rock mass, systematically studied the relationship between the typical roof falling accident of the gateway and the surrounding rock mass environmen t and provided the new roof falling cause classification standard and method based on coal drift roof falling control as a target. The roof fallings of coal drift were divide d in to four major types of"roof local block falling of the gateway with cracking surrounding rock mass",“complex roof falling of the poor binding layer surrounding rock mass", "roof falling type of the breaking surrounding rock mass gateway in a butterfly plastic zone' 'and"roof leakage type of the loose surrounding rock mass gateway" . Based on the circumstances, the roof falling prevention and control method was provided based on the roof falling cause classification of coal drift. Thus the roof falling control technical system would be the conventional bolt to control the local block falling, the normal anchor or anchor type resin bolt to control a small deformation comp lex roof falling, spring energy accumulated type anchor to control a broken roof falling in the large deformation butterfly plastic zone and the combined support to contro | the loose roof leakage and falling under the special condition.