LINEAR ROOF CUTTING FOR ROCKBURST PREVENTION AND ROADWAY PROTECTION IN DEEP MINING DISTURBED AREA

The disturbance between workface mining and roadway extraction is the main key factor that inducing rockburst disasters in the coal mines. The deep area is disturbed by large roadway deformation besides rockburst. Aiming to solve this common technical challenge,this paper proposes the linear roof cutting technology. Based on the key strata theory,firstly we analyze the structure characteristics of the key strata of inclined coal seam and reveal that the spatial occurrence of the key block B is critical for rockburst and surrounding rock control. Then the optimal fracture line of key block B of the inclined coal seam is suggested. Using the COMSOL software we simulate the rules of stress distribution after blasting with different charge diameters. The results show that the stress peak exponentially attenuates,and the fracturing area is positively correlated with the charge diameter in a power function. The fitting formula for the fracture zone under different charge diameters is obtained. Take the tensile strength of the roof rock as the index value,the optimal distance corresponding to the charge diameter can be determined. We design different in-situ schemes based on the geological conditions. The field experiments verify that the linear roof cutting technology has a significant effect on rockburst prevention and roadway protection,comparing to the traditional deep hole roof blasting since the crack can be penetrated between two adjacent blasting holes. So,the most important parameter for roof cutting is the distance of blasting holes. Through the displacement observation and microseismic monitoring,it is shown that the linear roof cutting technology can effectively reduce the deformation of the surrounding rock of the gob-side roadway,and at the same time reduce the rockburst of the working face. Field practice has verified the theoretical and simulation results,and provides a valuable reference for similar engineering.