Research on the influence of burial depth on the energy evolution law of coal and gas outburst

As the depth of coal mine mining advances year by year, the danger and harm of coal and gas outbursts are becoming more and more serious.In order to study the evolution law of coal and gas outburst energy with increasing burial depth, Pingmei No.12 Coal Mine was taken as the engineering background and typical outburst accident cases were selected that occurred during shallow (407 m), middle (731 m) and deep (1 108 m) mining process.By constructing an outburst energy calculation model, the evolution and release law of coal and gas outburst under different burial depths were explored.The research results showed that during the process of coal and gas outburst, the elastic energy of coal and rock and the gas expansion energy both increased with the burial depth.At the same burial depth, the gas expansion energy was 1 to 3 orders of magnitude higher than the elastic energy of coal and rock, which was the main energy source for the outburst.The outburst energy was mainly used for the crushing and transportation of the ejected coal.As the burial depth increased, the work required for coal fragmentation and transportation showed a logarithmic increase and exponential increase trend respectively.In addition, the effective desorption ratio was introduced to quantitatively characterize the proportion of gas expansion energy actually involved in expansion work to the total gas expansion energy in the outburst coal seam.It was found that the effective desorption ratio showed a linear growth trend with the increase of burial depth, indicating that deeper burial leads to a higher proportion of effective gas expansion energy and a greater risk of outbursts.