Gas emission-based determination of the reasonable driving speed in coal roadway

Scientific determination of the tunneling speed is an important prerequisite for the safe and efficient production in coal mines with high gas and outburst. In order to determine the reasonable driving speed of coal roadway and reduce the occurrence of dynamic disasters in coal roadway driving, the distribution law of gas in roadway head was analyzed, the mathematical model was established. Gas emission characteristics were also analyzed at different driving speeds based on the model. Taking Jinhui Wanfeng Coal Mine as an example, the reasonable driving speed was determined in this coal mine based on its gas emission characteristics. Results show that when the driving speed is equal to the stress migration speed(v=v_σ), the gas emission of fallen coal and the total gas emission are all constant; when the driving speed is less than the stress migration speed(v < v_σ), the gas emission of fallen coal decreases linearly, the total gas emission decreases continuously; when driving speed is greater than the stress migration speed(v>v_σ), the gas emission of fallen coal increase exponentially, the total gas emission decreases continuously; The stress migration speed of working face 1115 in Wanfeng Coal Mine is 2.1 m per shift or 2.4 m, 1.6 m and 2.4 m per shift circularly driving, at this speed the roadway can be safely and fast excavated. The research results were proved at inlet airway 1115 and the feasibility of the method was verified.