Seismic Earth Pressures on Deep Stiff Walls

Experimental and numerical studies of the seismic response of a deep, stiff basement structure were motivated by the fact that the current seismic design methodologies based on previous works predict very large dynamic forces in areas of high seismicity. The experimental program consisted of a geotechnical centrifuge model with a basement structure embedded in cohesionless backfill. The numerical analyses sought to replicate the results of the centrifuge experiment and to validate the use of numerical analyses for the prediction of expected behavior. Overall, the results of this study show that the Mononobe-Okabe method of analysis provides a reasonable estimate of the expected response of stiff basement structures provided depth-Averaged design accelerations are considered

Comparison of Pseudo-Static Limit Equilibrium and Elastic Wave Equation Analyses of Dynamic Earth Pressures on Retaining Structures

The seismic earth pressure increment is typically computed using either pseudo-static limit equilibrium methods or elastic wave equation analyses of the interaction between a retaining structure and backfill material, yet current interpretations of the two methods provide conflicting recommendations. The focus of this study is to compare the seismic earth pressure increment computed using the two methods. This approach is demonstrated by subjecting an initially uniform prototype site selected from standard site classifications to harmonic excitation in one-dimensional equivalent linear analyses. Then, the seismic earth pressure resultant for a rigid wall is computed using the two methods. The limit equilibrium approach utilizes the acceleration records from the equivalent linear analysis to compute a seismic coefficient, whereas the elastic solution incorporates the reduced modulus and damping from the final iteration of the analysis, as well as the relative displacement records. The results presented herein corroborate the findings of recent centrifuge experiments and associated analyses