The sequence of excavation for the shaft of diversion system at Pushihe storage power station is to excavate the pioneer well used by back well boring machine, then by hand air drill to expand it.
蒲石河抽水蓄能电站引水系统中的竖井开挖，拟采用反井钻机进行导井开挖，人工手风钻钻孔扩挖的方式施工。
2
Application of inverse welldrill will permit quick and safe excavation of pilot shaft.
应用反井钻机开挖导井可达到快速安全的效果。
3
On the contrary, the back welldrill method is from bottom to top, which is suitable for the small inclined Angle, but not for the large shaft section.