瓦斯压力对煤与瓦斯射流突出能量的影响

瓦斯压力是煤与瓦斯突出的主要动力源,其与突出能量的关系尚不明确。将煤与瓦斯突出视为煤-瓦斯气固两相射流突出,在分析煤与瓦斯射流突出过程的基础上,建立了煤与瓦斯射流突出数值模型,给出了突出能量表达式。通过理论分析、数值模拟相结合,得到了瓦斯压力对煤与瓦斯突出能量、突出强度、瓦斯涌出量等参数的影响规律。结果表明,突出发生时,突出能量具有波动性,即以突出口为界存在能量集聚骤升区和能量释放衰减区。能量集聚骤升发生在突出孔洞至突出口段,瓦斯-煤两相流突出速度成倍增大;能量释放主要发生在突出口附近和巷道中,瓦斯-煤两相流突出速度逐渐减小。煤与瓦斯射流突出产生强烈涡旋,在顶板、底板处尤为显著,与现场观察到的突出后顶板有摩擦和划痕、底板突出煤粉有分选现象一致。瓦斯压力与突出能量间呈线性增加关系,与突出强度和瓦斯涌出量均呈幂指数增加关系。计算得到的煤与瓦斯射流突出能量量级与前人结论基本吻合,结果可为煤与瓦斯突出能量预测提供参考。

Impact of the gas pressure on the jet outburst energy of coal and gas

Based on the analysis of the coal and gas outburst process,the present paper intends to propose a new method for predicting and forecasting of the coal and gas outbursts known as the gas-solid jet.The method has been proposed from the actual need to make clear the internal or interior relation between the gas pressure and the outburst energy that may account for the coal and gas outburst on the condition when the gas pressure turns to be beyond the maximum limit.Therefore,in response to the need,we have developed a coal and gas jet numerical model by using the ANSYS software,at the given pressure boundary conditions.Along with the model,we have provided for the coal and gas solid coupling calculation model with the energy expression of coal and gas outburst given.And,as a result,we have also worked out the impact of the gas pressure on such parameters as the energy of the coal and gas outbursts,the outburst intensity and the gas emission intensity.The results of our study show that there exists an energy concentration zone in the outburst mouth outlet,where the gassolid thrust velocity has to be multiplied with its maximum outburst velocity should be at least 5 times of the rest parts of the outburst break.At the same time,the energy outburst or release is mainly going on in the vicinity of the outburst break and the roadway,with the velocity being gradually lessening and weakening.What is more,the outburst of the coal and gas jet is endowed with a very strong vortex,particularly prominent at the top and bottom plates,which is consistent with the friction and scratches on the top plate,which can be observed when the pulverized coal get separated and split at the bottom plate in the coal field.Thus,the above analysis can help to make the conclusion that the energy can have a great volatility when the outbursts take place,namely,the outburst breaking points can separate the energy concentration zone from the energy release zone.The energy of the outburst tends to increase linearly with the gas pressure thrusting out.Statistically speaking,the gas pressure may increase from 0.5 MPa to 5 MPa,with the increase of the outburst intensity of the gas pressure in accordance with the power exponential law,though the increasing rate may tend to decrease from 17.75％ to 8.16％,indicating that the increasing relation between the gas pressure and the gas emission turns to be exponential.Thus,it can be found that the calculation result of the outburst energy proves to be consistent with that of the original calculation,whereas the energy magnitude of the coal and gas outburst that has been gained is also well in accord with the previous results.Therefore,through comparison and analysis of the coal and gas outburst samples in No.12 Mine of Pingdingshan Coal Mine Cooperation,the average error has been found equal to 4.45％,which is qualified enough to serve as a reference for prediction and forecast of the coal outburst energy strength.