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Abstract The arch dam in Jinping I hydropower station is the highest arch dam under construction in the world；the height of excavated slopes at abutments is over 500 m. The power station is located in high mountains and narrow canyons in Southwest China，where natural slopes are very high and steep with high geostress，intensive rock mass unloading，developed faults，interlayer compressive belts and deep unloading fissures. Based on detailed geological investigation，models of the slope structure and the corresponding failure mode are determined，such as tensile rip rock body at left bank above elevation 1 800 m；zoning and analysis of slope stability are also implemented. According to the characteristics of slope structure，the excavation and harnessing principles are determined as follows：little excavation，slight blasting and strong reinforcement，reinforcing each zone and layer respectively，holistic control and covering local weak points with global measures，local and global，implementing shallow and deep reinforcement controlling systems of slope with prestressed cables and shearing-resistance tunnels as main measures and bolts and concrete grids as complement. Time sequence of construction and blasting technique are precisely designed and firmly controlled to guarantee the quality of excavated rock mass；and dynamic design schemes and reasonable management rules are implemented to ensure the safety of construction. Monitoring data from July 2006 to September 2009 indicate that maximum displacement in surface part of the slope is 79.5 mm，in direction perpendicular to the river；and maximum deformation in deep unloading fissures is 60 mm with the maximum rate of 0.1 mm/d. The displacement tends to converge；and it meets the designed safety standards. The successful implementation of high slopes in Jinping I hydropower station provides new practical experience and reference for future construction of projects，and it indicates a new stage of the research and design of rock mechanics and engineering in China.
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Received: 31 December 2009
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