Development and application of novel unloading and monitoring approaches to the failure analysis of deep coal roadway

• Novel internal unloading technology overcomes the defects of traditional methods. • A novel monitoring approach for matching unloading effects was first proposed. • Providing compensation spaces for the movement of deep coal to the roadway. • Novel unloading and monitoring approaches can solve control problems of deep roadway. Based on the difficult problems of surrounding rock control in deep roadways and considering the defects and shortcomings of traditional unloading methods, this paper puts forward a novel internal unloading technology and a novel monitoring approach for matching unloading effects. The novel internal unloading approach is mainly to excavate large unloading holes in the deep peak-stress area. The novel internal monitoring approach refers to the arrangement of the retractable and expandable pressure-bag with regulating system in the internal invisible unloading spaces, which can dynamically monitor the closure of the internal unloading holes in real time and evaluate the unloading effects of surrounding rock. Through physical simulation and field engineering test, the reliabilities of novel unloading technology and novel internal monitoring approach were verified. The combination of the two novel approaches can solve the problems of surrounding rock control in deep continuous large-deformation roadways.