Stability analysis of dam foundation of extra-large hydropower station under complicated geological conditions—Taking Xiangjiaba hydropower station as an example

Abstract

The Xiangjiaba Hydropower Station dam site is located in the NEE direction of the eastern part of the shortest anticlinal part of Tang Fang Wan. There are NW-shaped vertical coal knee flexures, more weak intercalations, compression zones, small faults, and joint fracture structures, the geological structure at the dam site is very strange and complex, with more unfavorable anti-sliding stability and seepage stability of the dam foundation. Based on these unfavorable factors, a series of engineering measures have been adopted to ensure the stability of the dam foundation. In this paper, based on the deformation and seepage monitoring data of Xiangjiaba Hydropower Station, the influence of the water level rise on the dam's foundation in terms of the settlement, seepage, and slide-resistant stability after all previous impoundments is analyzed. The results show that the deformation and seepage of the dam's foundation are within normal limits, and the uplift pressure generally meets the requirements of the code. The practice has proved that under complex geological conditions, effective engineering measures can ensure the stable operation of the dam foundation.