Energy Absorption And Rockburst Weakening Theory For High Impact Toughness Rock Bolt And Its Applications

In view of the current support problem of roadway with rock burst, taking Changcun coal mine in Yima mine area as the research background, the instability failure cause of roadway with rock burst, dynamic mechanical property of coal and rock mass under the impact load and shock resistance of high impact toughness bolt were studied based on the comprehensive research method combined with lab experiment, numerical simulation, theoretical analysis and underground test, the main results are as follows.(1)The research results suggest that the joints and fissures developed in coal and rock mass after roadway excavation greatly reduces the integrity and strengthen the strain rate sensitivity of the coal and rock, and then increase the plastic deformation capacity of fractured coal and rock.(2)High impact toughness bolt with high strength, high impact toughness and high elongation can withstand impact load produced by rock burst. Meanwhile, the rod body can yield and absorb energy under the high strength, which has good features of energy absorption and rockburst weakening and is not easily broken under dynamic load. High prestress can improve cohesive force and sliding resistance force and reduce plastic deformation capacity of fractured coal and rock mass to enhance the stability of coal and rock.(3)Based on the above research results, the model for energy absorption and rockburst weakening of high impact toughness bolt is stablished and rockburst prevention and anti-knock mechanism is analyzed, the concept of high impact resistance and the principle of high impact toughness bolt energy absorption and rockburst weakening are presented. It is obtained that from the rockburst prevention and anti-knock mechanism, the high impact toughness bolt and surrounding rock of roadway can form a common body of high impact resistance. High strength anchor cable is used to make common body of high impact resistance and deep rock mass to be a composite body of impact resistance and increase the bearing structure of surrounding rock and thickness and strength of anchoring layer. High strength anchor cable can not only provide a larger bearing load, but also can guarantee compatibility of deformation between common body of high impact resistance and deep rock mass and so avoid instability failure due to uncoordinated deformation of common body of high impact resistance under impact load. The composite body of impact resistance can overallly produce high-intensitive yield and energy absorption along with the impact direction of shock wave and so dissipate the large amount of impact energy released fromrock burst.(4)Based on the mechanics and energy dissipation model, the stress judgement and energy criterion for rockburst prevention and anti-knock of common body of high impact resistance are determined. It is shown that coordination of deformation between high impact toughness bolt and surrounding rock of roadway is the main way to dissipate the energy of rock burst. By increasing the parameters such as pre-tightening force, strength, impact toughness, support density and so on, impact resistance of surrounding rock of roadway can be effectively improved.(5)The research achievement has been used in field and solved the support problem of roadway with rock burst and obtained good supporting effect, which further validate the validity of energy absorption and rockburst weakening theory for high impact toughness rock bolt.