Construction Control Technology of Ultra-deep Inclined Directional Drainage Holes in Left Bank Abutment of Longyangxia Hydropower Station

Abstract:

Imported from Sweden, Atlas-A32 down-the-hole drill was used in 4 ultra-deep inclined directional drainage holes with diameter of 130 mm and depth of 80m in the left bank abutment of Longyangxia hydropower station, drilling from abutment EL2610 to the theoretical design borehole bottom location EL2530 drainage gallery(2m×2.5m). According to the difficulties caused by drilling tool vertical deviation of 3% (vertical deviation of 3% is verified to be scientific). The technical bottleneck of too large vertical deviation in ultra-deep directional hole construction with down-the-hole drill were overcome on the control of technical parameters and technology. The paper summarizes technical achievements of ultra-deep inclined directional holes constructed with Atlas series down-the-hole rotary percussion drill from Sweden.