Pseudostatic analysis for seismic slope stability of dike

• Main Author: Chong, Wan Yoon.
• Other Authors: Budi Wibawa
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Civil engineering::Geotechnical
• Online Access: http://hdl.handle.net/10356/52596
• Institution: Nanyang Technological University

This report describes a pseudostatic analysis for seismic slope stability of dike with simulation study using PLAXIS 2D Finite Element Program and GeoStudio SLOPE/W analysis. Much focus is given to the comparison of factor of safety of the dikes obtained from 84 dike models created using these two programs, with variation being made on the seismic coefficient and ground water level of the model. A sand dike of 16m height, 120m base width, and 8m span across the top is adopted as the model in this study. The seismic coefficient opted for this pseudostatic analysis increases from 0.10 to 0.15. The water heights of the soil model increases from 8m to 14m above ground. The increase in seismic coefficient has found to bring the safety factor of dike to a lower value in both programs, also proven to increase the dike displacement from the PLAXIS readings. The effect of ratio of water height to dike height is more significant during the initial stress state where seismic coefficient, kh = 0. Increase in the water height to dike height ratio lowers the factor of safety when the slip surface is on the right of dike, where water level is below ground surface. While the slip surface falls on the left of the dike, the change in safety factor is less significant from both PLAXIS and GeoStudio data. After pseudostatic analysis and application of positive acceleration to the sand dike, the slip surface falls on the left of the dike and changes in factor of safety is less significant, due to additional stabilizing effect from the water pressure acting on the slope. Comparing the factor of safety output from PLAXIS and GeoStudio, PLAXIS results appear to be more conservative than GeoStudio results. Limitations of both the programs and the pseudostatic approach will be concluded at the end of this report.