Abstract: In the spillway control section of the Qianping reservoir, excavation to the foundation surface reveals its geological conditions greatly different from the survey data obtained previously. A supplementary geological survey verified that this section is actually located in a contact zone between andesitic porphyrite and diabase with its base plane mostly on a strongly weathered deep bedrock. The weathering degree of diabase rock is non-uniform with the maximum exposure depth of 10.2 m at the exploration hole; the nature of rock mass is heterogeneous, featured with a soft-hard interphase layer and a potential risk of local stress concentration and uneven settlement. To solve these problems, we optimize the foundation treatment of the spillway control section and achieve the treatment goals through several measures such as excavation and replacement of concrete, anti-slide piles, and reinforced concrete anti-slide slots.

Key words: spillway control section, strong weathered bedrock, foundation treatment, scheme optimization