ABSTRACT
The Kali Gandaki “A” Hydroelectric Project is a 140 MW power project on the Kali Gandaki River in south central Nepal. Initially the powerhouse was to be located underground. The computer code FLAC was used to evaluated the feasibility of constructing that facility. Only the Mohr-Coulomb material model was used for this analysis. The rock is weak phyllite with strengths as low as 1.0 MPa and is characterized by pronounced foliation coupled with jointing and clay filled shear zones. The rock is soft and weak. Removing horizontal slices from the grid, starting at the crown and working downward simulated rock excavation. The Mohr-Coulomb material model was used to represent the phyllite. As each slice was removed rock dowels and long cable bolts were added as ground support. Runs were made with varied rock properties and bolting configurations. The results showed a significant risk for failure in the powerhouse wall as the excavation advanced downward. The underground powerhouse option was abandoned and a surface option adopted.
