Mechanism of uplift deformation of the dam foundation of Jiangya Water Power Station, Hunan Province, P.R. China

Uplift deformation of Jiangya Dam in Loushui River, Hunan Province, P.R. China reached 28.4–32.6 mm in 2 years and 5 months (December 1998–April 2001), which is unusual for dams worldwide. A perfectly confined aquifer, Yuntaiguan hot water aquifer, in the Jiangya syncline is recharged at a remote wing and outflows in front of the dam in the reservoir which is 875 m lower than the recharge point. The rise of the reservoir water level increases the head in the aquifer. The uplift deformation of the dam foundation corresponds spatially with the outcrop of the top interface of the aquifer and shows a direct time response to the fluctuation of the reservoir water level, indicating that the fluctuation of the reservoir water level is the dominant influence on the deformation. Numerical simulation shows spatial and dynamic similarities to the monitoring data. Numerical simulation of the cyclic reservoir water level confirms that the uplift is due to elastic deformation.