No abstract

Based on the pipe transportation of paste-like backfilling system of a certain deep coal mine, its dynamics process was simulated and analyzed. A two-dimensional dynamic model of extraordinary deep and lone pipe was built by GAMBIT, on the basis of which the simulation was done by implicit solver of FLUENT 2ddp. The results show that hydraulic loss of pipe transportation is less than the pressure produced by gravity, which means the backfilling material can flow by itself. When the inlet velocity is 3.2 m/s, the maximum velocity of 4.10 m/s is at the elbow and the maximum velocity in the horizontal pipe is 3.91 m/s, which can both meet the stability requirement. The results of the simulation are proved to be reliable by the residual monitor plotting of related parameter, so it can be concluded that the system of pipe transportation is safe.

No abstract

The impact mechanism of in situ stress on outbursts plays a key role in the prevention of outbursts during deep coal mining. The in situ stress may influence the outburst by affecting the gas release intensity according to theoretical analysis, but none of the existing studies have taken into consideration this perspective. To explore whether the influence of in situ stress on gas release in coal is an important reason for stress-induced outbursts, experiments on gas release in coal under different axial stresses and on exposure-induced outbursts with different gases were conducted to respectively study the influence of in situ stress on gas release and the impact of gas release on outburst. The results show that with the increase of stress, the methane release intensity rises by 1~2.4 times and shows an obvious periodicity due to different degrees of fracture development. A small increase in gas release intensity can lead to huge increase in the outburst intensity based on an energy analysis of the outburst experiments, indicating that the gas release intensity is a sensitive physical quantity that influences outbursts. The differences in gas release in coal with different stresses will result in differences in the outburst results based on data from the two experiments, proving that the change in gas release intensity during variations of in situ stress is an important factor for in situ stress-induced outbursts. The research achievements can enrich the impact mechanism of in situ stress on outbursts.

No abstract