| Failure of an earth dam can cause significant economic damages and loss of life. The behavior of earth dams during earthquakes has been studied for many decades by geotechnical engineers. An important element in evaluating the risk associated with the failure of an earth dam induced by earthquake is the probability of failure. Various responses of an earth dam during and after an earthquake were studied. Those responses included seismic deformation, liquefaction, and post-liquefaction stability. Both deterministic and probabilistic approaches were used. Deterministic and probabilistic seismic analysis frameworks were set up in order to organize the analyses required. A dynamic finite element technique was used to determine the seismic responses of a dam. The results from the dynamic response analysis were then used in liquefaction potential analysis and seismic deformation analysis. The relationship between post liquefaction shear strength and Standard Penetration Test (SPT) number from many references were gathered. The data were revised and plotted to obtain a new relationship. Post-liquefaction stability of a dam slope was evaluated based on those relationships. Probabilistic approaches were applied in order to determine the probability of failure. The Simplified First Order Second Moment (SFOSM) method was used for the seismic deformation analysis, dynamic response analysis, and post-liquefaction stability analysis, in order to obtain the probability of failure. Hills Creek Dam located near Eugene, Oregon, was used to demonstrated the approaches. |
