METHOD FOR SUPPORTING VERY HIGH ROCK WALLS IN UNDERGROUND POWER STATIONS

TO BUILD THREE UNDERGROUND POWER STATIONS WITH VERTICAL- AXIS GENERATING AND PUMPING SETS, CAVITIES WITH 60-M HIGH WALLS HAD TO BE EXCAVATED. IN TWO OF THE POWER STATIONS, THE ROCK WALLS WERE SUPPORTED DURING EXCAVATION BY MEANS OF ANCHOR ROPES UP TO 30 M IN LENGTH, EACH WITH A BEARING CAPACITY OF UP TO 100 TONS. THE ROCK WALLS WERE ALSO LOCALLY STRENGTHENED BY BOLTS AND SHOTCRETE. FOR THE LAKE DELIO POWER STATION, THE LARGEST OF THE THREE, A DESCRIPTION IS GIVEN OF THE EXCAVATION STAGES, THE PRINCIPLES GOVERNING THE CALCULATIONS FOR THE ANCHOR-ROPES, AND THEIR CHARACTERISTICS AND PLACING TECHNIQUE. /AUTHOR/