煤系地层开挖水库隧洞的工程地质及涌出量分析

Analysis on Engineering Geology and Emission Quantity of Reservoir Tunnel in Coal Measure Strata Excavation

水库隧洞穿越煤系地层时,容易引起瓦斯的释放及爆炸危害,文章依托柴河水库供水隧洞工程,利用工程地质调查分析瓦斯隧道的工程地质特征,并对瓦斯的涌出量进行理论计算。研究成果表明:瓦斯绝对涌出量为0.27m^2/min,为低瓦斯地层;断层与洞室的夹角约50°,影响带宽度约80m,开挖前,建议采用适当的超前支护措施,开挖后及时全断面支护,保证洞室稳定性。建议做好超前地质预报,并做好瓦斯监测记录,当工作面瓦斯浓度达到0.5%时,应立即撤出人员,加强通风。隧洞掘进过程每循环在拱部打5个、底部打3个钎探(深度5m)做瓦斯探测,出现不良地质征兆时可及时处理。所得结论对今后类似工程具有重要的参考和借鉴价值。

It is easy to cause gas release and explosion hazard when reservoir tunnel passes through coal measure strata.The engineering geological characteristics of gas tunnel is analyzed by engineering geological survey based on the water supply tunnel project of Chaihe Reservoir in the paper,and the gas emission quantity is calculated theoretically.The research results show that the absolute gas emission quantity is 0.27m^2/min,which is a low gas strata.The included angle between the fault and the cavity is about 50°,and the influence belt width is about 80m.It is recommended to adopt appropriate advance support measures and timely full-section support after excavation to ensure the stability of the cavity before excavation.It is suggested to make advanced geological forecast and gas monitoring record.Related personnel should be evacuated immediately and ventilation should be enhanced when the gas concentration of working face reaches 0.5%.5 drilling holes are drilled at the arch and 3 drilling holes are drilled at the bottom(depth of 5m)for gas detection in each cycle during the tunneling process,which can be timely dealt in case of poor geological signs.The obtained conclusions have important reference value for similar projects in the future.