The uplift mechanism of the rock masses around the Jiangya dam after reservoir inundation, China

During filling of the Jiangya reservoir, a multi-purpose project in China Hunan province, it was found that the dam body and the rock masses on both valley sides were uplifted to various degrees, with a measured maximum uplift of 32.6 and 19.08 mm, respectively. This rare phenomenon caused concerns from various parties. The paper presents a systematic analysis on the factors that may possibly contribute to the uplift, on the basis of a comprehensive study of the geological background of the project and the observed data. To confirm the uplift mechanism of the confined hot aquifer, 3D numerical analysis and rock mechanical model test were also carried out. It is concluded that the rise of artesian head of the confined hot aquifer as a result of the reservoir inundation is the principal factor contributing to the uplift.