Research on key technologies in the development of Nam Ngiep 2 Hydropower Project in Lao PDR

Xianming Chen, Xuechuan Qi, Zongmin Wang, Fang Jin

Monday 29 june 2015

17:30 - 17:33h

Themes: (T) Water engineering, (ST) Experimental facilities and instrumentation, Poster pitches

Parallel session: Poster pitch: 3F. Engineering - Instrument

Nam Ngiep 2 Hydropower Project situates in the southeastern part of Jars Plain, Xieng Khouang Province, Lao PDR. It is designed with an installed capacity of 3x60MW and an annual average power production capacity of 7.21×108kW.h. During the development, a series of key technologies have been applied in the development plan, dam construction aggregates and spillway design for energy dissipation. In view of the unavailable condition for dam construction, insufficient runoff and highly variable seasonal flow in the main course of Nam Ngiep River, research has been conducted to adopt a long distance water diversion development program, i.e. the Nam Ngiep River water is diverted through a 8.15km tunnel to Nam Sen River, on which the dam is suitably constructed, then through a 11 km long tunnel to Nam Siam River, finally flows into the downstream of Nam Ngiep River. Thus, the reservoir capacity of 1.577×108 m³and a water head of 491m can be effectively utilized for electric production. Given the limited source of the aggregates, abundant clay deposit and thick layer of all weathered overburden in the dam foundation at the dam site, a research on using the all weathered rock for dam construction was carried out. Dynamic tests, relevant static and dynamic calculations and system analysis showed that it is safe and feasible to use the excavated material and weathered rock next to the dam for dam filling. It not only effectively reduced the construction cost but extended the use of local materials in dam construction. Meanwhile, the swallow-tail type flip bucket technique was advised for energy dissipation and the test undertaken indicated that the design dispersed the flow longitudinally, decreased the unit area inflow, reduced downstream scouring, and lowered the ski-jump water level in the spillway, thus effectively solved problems in low flow flood discharge. This was an innovative technique. Key Words: Nam Ngiep Hydropower Project Key Technologies