ABSTRACT
The stability of a large-scale hydropower dam structure on a soil foundation with excessive pore water pressure and reduced effective stresses due to static liquefaction during construction and later internal erosion is calculated for deep-seated bearing failure mechanisms by an innovative approach. The in-situ effective stress in the foundation soil under the dam structure was investigated by several Cone Penetration Tests (CPTs). By reverse interpretation of these CPTs, reduced effective stresses in the foundation soil in depth are quantified. In the 2D FEM calculation model, the reduced effective stress zones below the dam structure are incorporated with clusters of the size about 5 m x 10 m. They are assigned with different permeabilities and unit weights to calibrate with the measured pore pressures, drainage discharges and CPT reversely interpreted effective stresses. Safety factors are calculated by the Shear Strength Reduction (SSR) method with the 842calibrated models. A wide range of sensitivity analyses are also conducted to verify the results and extend the understanding of dam stability.
