Abstract:

Geological disasters occurred frequently since the impoundment level of Three Gorges reservoir area reached 175mm. Especially in Wu Gorge where the geological environment is vulnerable, an amount of 380 000m³ collapsed at Gongjiafang slope in 2008, causing surge waves of 13m high, severely affecting the safety of waterway transportation. Through data gathering, ground investigation, engineering geology surveying and mapping, we researched the engineering geology and bank slope structure, and identified 18 potentially unstable slopes according to the bank slope’s deformation and failure features. Analysis shows that the deformation failure mode are composite bending-toppling, V-shape toppling and interlayer shear failure, which would give rise to toppling and sliding instability. There are three failure mechanisms: progressive failure, brittle failure in “locked area” and integral failure. The research achievements provide reference for similar high steep bank slope research in the future and for disaster prevention and mitigation in Three Gorges area.

Key words: Three Gorges reservoir area, Wu Gorge, high steep slope, instability mode, deformation and failure mechanism