Construction of the underground powerhouse of the Hoabinh hydraulic development

Conclusions

• 1. Construction of projects of a similar type with the required concentration of forces can be carried out in their full rock excavation volume in a period of 4–5 years.

• 2. Startup-adjustment work and operation of the units can be combined with the carrying out of the drilling-blasting work for construction of the powerhouse. However, taking into account the above-mentioned times of completion, it is not desirable to include such a work combination in the projects.

• 3. In the construction of similar structures, having walls exposed over a considerable height, independently of the strength of the intervening rock, it is essential to strengthen the walls with concrete.

• 4. Taking into account the complexity of the structure, the powerhouse adits, the accesses to the powerhouse, and different excavation tiers should be designed and constructed during the preparatory construction period.

• 5. To preserve the stability of the walls of long-span chambers, shafts in the junction adits should be made after strengthening the walls with concrete at the shaft places.

• 6. The adopted scheme for excavations of the pits of units Nos. 4–8 can be recommended for construction of similar projects in the absence of transportation access adits to the lower levels.