多煤层高瓦斯隧道爆破后瓦斯异常涌出量预测模型分析

Prediction Model Analysis of Abnormal Gas Emission after Blasting in Tunnel with Multiple Coal Seams and High Gas Concentration

瓦斯隧道爆破施工会导致短时间内大量瓦斯异常涌出,极易造成瓦斯超限,威胁隧道安全生产。为了对多煤层高瓦斯隧道爆破后的瓦斯异常涌出量进行科学预测分析,在对隧道瓦斯涌出影响因素进行分析的基础上,确定了瓦斯涌出源,进而建立了瓦斯异常涌出量的分源预测模型,并以天城坝隧道为研究对象,结合现场实测数据对预测模型进行了验证分析。研究结果表明:多煤层高瓦斯隧道爆破后瓦斯涌出源主要包括隧道开挖断面、隧道爆破落煤、隧道围岩周壁及邻近煤层,其中隧道爆破落煤瓦斯涌出量占绝大部分;该模型对爆破后瓦斯异常涌出量的预测值与实测值的相对误差在10%以内,预测准确度较高,对于隧道瓦斯异常涌出量的预测及瓦斯治理具有一定的指导意义。

Blasting construction of gas tunnel may lead to a large amount of abnormal gas emission in a short time,which causes gas overrun very easily and threaten the safe production of the tunnel.Based on the analysis of the influencing factors of gas emission,the gas emission sources were determined and a separate source prediction models of abnormal gas emission was established in order to scientifically predict and analyze the abnormal gas emission after blasting in the multi-seam and high-gas tunnel.Then,the prediction model was verified and analyzed on the basis of Tianchengba Tunnel as the research object and in combination with the field-measured data.The results indicate that:the gas emission sources after blasting in the tunnel with multiple coal seams and high gas concentration mainly include excavation section,coal falling after blasting,surrounding rock wall and adjacent coal seams,of which the gas emission from coal falling after blasting accounts for the vast majority;For the model,the relative error between the predicted value and the measured value of abnormal gas emission after blasting is less than 10%,so that its prediction accuracy is high.Moreover,it has certain guiding significance for predicting abnormal gas emission and gas control in tunnel.