Abstract:
For ultra-thick coal seams with strong rock burst tendency, it is difficult to select proper unloading measures. This investigation compared three unloading methods, such as large diameter unloading borehole method, deep-hole unloading method, and water-injecting method by theoretical study and field monitoring, and some conclusions are drawn. The large diameter unloading borehole method with good timeliness takes slow effect and therefore it can be viewed as a regular unloading method. The deep-hole unloading method with poor timeliness takes a fast effect and hence the stress will recover in a short time. This method can be selected as a temporary unloading method. The water-injecting method with good timeliness takes moderate effect; however, the stress will transfer and roadway may deform heavily. This method can be taken as dust-prevention not rock burst prevention measure for longwall panels with small roadway sections.