Mechanical feature analysis and countermeasure on drilling in the outburst soft coal seams

The precondition to realize the gas drainage is drilling. But it is very difficult to drill in the outburst and soft coal seams, especially to drill the deep holes in these regions. The phenomena such us the hole falling down, hole breaking down, hole spraying or the drill rod broken often occur. Those phenomena have a strong relationship with the soft coal features and the high gas existing, and can be taken as the result both of the gas resolution releasing and the mechanical action. To reduce or overcome the problems those occurring in the drilling process, should use an integrating method. This paper has analyzed the mechanical feature of the drilling cutting process and discussed the methods should be taken to solve the problems occurring in the course of soft coal deep hole drilling The discussing contents here are limited to the aspects of the drilling mechanisms, such as the aiguilles, the combination tools and the rods, etc.