Study on Application of a Five-step Approach to Gradual and Fast Coal Uncovering during Gassy Tunnel Construction

A five-step approach to gradual and fast coal uncovering during gassy tunnel construction is developed to address high risks and tunnel construction safety problems related to protracted coal uncovering. By examining the technical principle of gradual and fast crosscut coal uncovering technique, this paper concludes multi-parameter prediction is the key to this technique. It establishes multi-parameter prediction criteria for coal burst hazard and multi-dimensional arrangement of prediction holes; discusses how to set up a movable safety barrier zone and determine its scope; and develops a gradual and fast coal uncovering process for construction of gassy tunnels by which the burst-prone coal seam is uncovered through gradual excavation and advancement under the protection of the safety barrier. Application of this technique on the construction site of Huayan Tunnel shows this technique is easy to apply, economical and safe and significantly reduces the time spent on coal uncovering.