Numerical analysis of the anti-liquefaction performance of a water reservoir dam under self-weight consolidation

The embankment dam on the Qingcaosha Reservoir in Shanghai, China, was constructed on slightly or moderately liquefiable ground without a special foundation treatment. The designers considered to use the self-weight consolidation from the dam to improve its anti-liquefaction performance. To assess the liquefaction mitigation effects of this simple method, an effective stress analysis method was utilized to simulate the seismic responses of the reservoir dam. The numerical method was first validated using a centrifuge test. The dynamic performance of the dam was then analyzed for three cases: during a free-field period without dam construction (case 1), during completion of the construction of the dam in a short period of time (case 2), and 5 years after construction of the dam (case 3). The effects of liquefaction remediation were analyzed based on the excess pore water pressure ratio (EPWPR), the vertical and lateral displacements, the effective stress path, and stress-strain relationships. The remediation method, done using self-weight consolidation, reduced the EPWPR generated within the foundation soil, decreased the vertical settlement (from 27 to 20 cm) and the lateral displacement (from 21 to 20 cm) of the dam structure, and increased the stiffness of the foundation soil. In addition, the mechanisms underlying the remediation effects were also elucidated.