Coal stratum was encountered during excavation of inclined shaft No. 4 of Wushaoling Tunnel, and gas was released.
乌鞘岭隧道4号斜井施工中突遇煤层，并有瓦斯释放。
2
Methods An inclined tube well collecting percolating ground water with powerful pump in the water-bearing stratum in the depth of 30 meters below the riverbed of Huanghe River was built.