Prestressed anchor cable construction technology in tailrace tunnel of underground powerhouse in Three Gorges Project
Xiaochuan You · Yangtze River · 2010
The tailrace tunnel with sloping ceiling is adopted in the TGP′s underground powerhouse project,and grade 2000 kN unbonded dual-protection prestressed cable is applied in the anchoring of divergent and connecting sections of the tailrace tunnel with cable hole depth of 15～18 m.As dual protection for the cables by corrugated pipe and cement slurry is used,the anchor cable construction difficulties are increased.In the construction process,the follow measures are taken to ensure construction quality:controlling hole deviation,maintaining hole diameter,manufacturing and installing un-destructed cable body,full-hole grouting,multiple grouting pipelines,graded tensioning by controlling stress-strain.We give an overall introduction of unbonded dual protection prestressed anchor cable,and mainly discuss the difficult problems such as grouting and prestress loss etc.