隧道揭煤区域预测钻孔控制范围研究及应用

Research and application of drilling control range for regional prediction of coal uncovering area in tunnel

隧道穿越煤系地层时,将面临煤与瓦斯突出危险。准确测定煤层突出参数是确保隧道安全、经济生产的重要因素。在隧道大断面开挖应力扰动情况下,研究分析揭煤区域预测钻孔控制范围,确保隧道安全施工具有重要的意义。以宝鼎2号隧道为工程实例,运用理论分析、数值模拟的方法对隧道大断面开挖过程中前方垂距10 m的煤层应力变化规律进行研究,得出煤岩应力场分布特征。推导出隧道揭煤区域预测钻孔竖直方向控制范围距隧道上轮廓线应至少为12 m,距下轮廓线应至少为8 m;水平方向控制范围距左、右轮廓线均应至少为8. 5 m。同时,通过对K15+836煤层现场应用,测得原始应力区瓦斯含量远大于应力扰动区,说明原始应力区瓦斯参数指标才能真实准确反映煤层突出危险性。

When the tunnel passes through the coal measures strata,it will be confronted with the danger of coal and gas outburst.Accurate determination of coal seam outburst parameters is an important factor to ensure tunnel safety and economic production.It is of great significance to predict the drilling control range and to ensure the safe construction of the tunnel under the stress disturbance of large section excavation of the tunnel.Taking Baoding No.2 tunnel as an example,by means of theoretical analysis and numerical simulation,the stress variation law of coal seam with a vertical distance of 10 m ahead in the process of large section tunnel excavation was studied,and the stress field distribution characteristics of coal and rock were obtained.The following conclusions were drawn,vertical drilling coal region prediction control range contour line from the tunnel should be at least 12 m to derive the tunnel,the underline should be at least 8 m;horizontal control range of left and right contour should be at least 8.5 m.At the same time,through the field application of K15＋836 coal seam,the original stress area is far greater than the stress disturbed area of gas content,the original stress zone of gas parameters,and this conclusion showed that the gas parameters in the original stress area can reflect the risk of coal seam outburst accurately and accurately.