Unsupported roof distance determination of roadway excavation using difference method and its application

One method of unsupported roof distance determination was proposed.Firstly,roof mechanical model for stability analysis was established,then relation between roof stress distribution and unsupported roof distance was got using difference method.According to roof stress and its compressive strength and tensile strength to determine roof stability,rational unsupported roof distance was got.According to production and geological condition in 9802 working face of Zhangshuanglou Coal Mine,rational unsupported roof distance of 6 m was got applied this method.Under 6 m circulation footage condition,through temporary support and high pre-stressed bolt in 2 m minor cycle,surrounding rock is well controlled,and the excavation speed is increased.