Experimental Study On Rockburst Generation Process Of High Stress Roadway In Coal Mine

Rockburst generation mechanism and the mechanism of its key impacting factors for deep rock mass under high stress is of vital importance for stability control of roadway surrounding rock in deep dynamic disaster.This paper focused on the generation mechanism of Rockburst and its occurrence process for deep-buried rock mass with high stress.The test system was developed and similar materials were selected to recreate the occurrence and development process of Rockburst for deep-buried rock mass by 32times Three dimensional and 29 times Two dimensional test.Besides,the digital photographic measurement technology,acoustic emission monitoring and the stress and strain monitoring were comprehensively used to study the generation mechanism,catastrophe process,occurrence conditions,classification criteria and the prediction methods of Rockburst for deep-buried rock mass with high stress,and the main results and conclusions can be drawn as follows.?1?The simulation testing system of Rockburst for High Stress Roadway,consisting of confining pressure box,elastic energy storage structure and the excavation device,was independently developed.This testing system can effectively solve the stress break problem caused by the untimely oil supply of the rigid testing system,and realize the equal stiffness energy supplement during the whole Rockburst generation and catastrophe process.Besides,the elastic-brittle rock-like materials?patent number:201510466941.9?,which were suitable for experiment simulation of Rockburst,were invented.Rockburst phenomenon of the rock-like materials with four different kinds of physical and mechanical properties was successfully reproduced.?2?The whole disaster evolution process for three kinds of elastic-plastic rock-like materials and one kind of elastic-brittle rock-like materials was obtained through 36 times of simulation tests for High Stress Roadway,and the whole disaster evolution process for those four kinds of rock-like materials all contained static,static and dynamic combination,and dynamic failure.The disaster intensity factor?|_???₁,?₂?was defined,and the dual-index Rockburst classification criteria based on block ejection velocity and the disaster intensity factor were proposed.Besides,we also found that the influence of these two factors?block ejection velocity and the disaster intensity factor?on the failure mechanism and failure process of rock-like materials was not independent,but interactive.The structure remodeling completion criteria were proposed,and the nature that the Rockburst dynamic disaster occurred for the rock mass with the impact energy coefficient less than 1 was revealed.?3?The structure bearing behavior and spatial energy release characteristics for the free space surrounding rock were studied,and the most favorable section shape,size,location,formation and the distribution principle for the free space,which can prevent the Rockburst dynamic disaster,were obtained through 29 times of simulation tests.?4?The influence of interaction between the lithology,loading rate and the initial stress level on equivalent failure strength,initiation energy density,equivalent elastic?compression?modulus,deformation modulus in the disaster process and intensity factor for the rock-like materials during the Rockburst dynamic disaster generation and failure evolution process was studied,and three kinds of Rockburst generation and disaster-causing mechanisms were revealed.?5?The speed learning machine method was introduced to the Rockburst prediction field.Taking the impact energy coefficient,initial stress level and the loading rate of the rock-like materials as the input factors,we took the results of the 36 times of simulation tests as the analytical models to predict whether the Rockburst occurred and the corresponding gradation.The prediction results showed that the speed learning machine method can find the intrinsic characteristics of the training data set,and the model output can be accurately predicted.?6?The stability control technology of"Spatial and temporal scale control of free space"was put forward.The field application test showed that the free space formed at the position of pressure relief hole of coal pillar excavation and the limit of working face mining speed can efficiently reduce the adjustment rate of loading stress for the coal pillar,and prevent the impact Rockburst.