Analysis on stability of rock surrounding heading faces and technical approaches for rapid heading

Analyzes the current status and problems of coal mine roadway heading technology and equipment.The main influencing factors of the stability of surrounding rocks are analyzed,including geomechanical parameters such as surrounding rock strength,surrounding rock structure and in situ stress,excavation parameters such as roadway section size,excavation method,unsupported roof distance and excavation speed,as well as temporary support and permanent support.After excavation,the stress concentration zone appears around the top corner of the excavation face and the four corners of the roadway.The displacement and damage of the surrounding rock starts to appear at a certain position in front of the excavation face,and increases as it moves away from the excavation face,and basically stabilizes when it reaches twice the width of the roadway.The influence of coal seam strength and in situ stress on the deformation and damage of surrounding rock is very significant.The amount of roof sagging and the damage degree of staged excavation is obviously larger than that of one-time excavation.The larger the unsupported roof distance,the more cracks and the wider distribution range of fractures in surrounding rock.Too fast and too slow excavation speed is not good for the stability of surrounding rock.The temporary support with timely,active and large support resistance is good for the stability of surrounding rock.The displacement and fracture field of surrounding rock by support for several time is greater than that of support once,and the increase of excavation speed by support for several time is at the cost of affecting rockbolting effect,which should be limited to certain surrounding rock conditions.According to the unsupported roof distance and self stabilization time of the heading face within coal seams,the stability of surrounding rock is classified and the corresponding support requirements are proposed.The concept of excavability of coal roadway is proposed and the excavability of coal roadway is classified according to the conditions of the excavated coal measures.The drillability and anchorability of surrounding rock and the influence on excavation speed are analyzed.The main technical measures to improve the heading speed of coal roadway are proposed:to determine the suitable excavation mode,optimize the excavation process and select the excavation equipment;to determine the reasonable support form and parameters and appropriately reduce the support density;and to mach and coordinate the whole system of heading.According to the stability,excavability,drillability and anchorability of surrounding rock,the overall structure of coal heading automation and intelligent technology is proposed,and the key technologies should be solved:automatic and intelligent cutting,temporary support,automatic bolt installment,adcanced detection,positioning and navigation,surrounding rock stability and environmental monitoring and big data analysis,etc.Finally,the development path of coal heading automation and intelligence in China is proposed.