Seismic stability of reinforced-soil wall by pseudo-dynamic method

Abstract

Determination of the internal stability of reinforced soil walls under earthquake conditions is an important part of seismic design. The horizontal method of slices is used for determining internal stability or for tieback analysis of the reinforced soil wall. A pseudo-dynamic method is adopted in the present analysis, which considers the effect of phase difference in both the shear and primary waves travelling through the backfill due to seismic excitation. Reinforced soil walls with cohesionless backfill material have been considered in the analysis. Results are presented in graphical and tabular form to show the required tensile force and length of geosynthetic reinforcement to maintain the stability of the reinforced soil wall under seismic conditions. The effects of variation of parameters such as soil friction angle and horizontal and vertical seismic accelerations on the stability of the reinforced soil wall have been studied. With an increase of seismic accelerations in both the horizontal and vertical directions the stability of the reinforced soil wall decreases significantly, and thus greater strength and length of the geosynthetic reinforcement are required to maintain stability of the wall. The seismic vertical acceleration in an upward direction gives higher values of the required geosynthetic tensile strength, and the seismic vertical acceleration in the downward direction yields higher values of the length of geosynthetic reinforcement. Comparisons of the present results with available pseudo-static results are shown, and the limitations of the pseudo-static results are highlighted.