Location of Failure Plane and Design Considerations for Narrow Geosynthetic Reinforced Soil Wall Systems

Abstract

The design of a Geosynthetic Reinforced Soil (GRS) wall for internal stability against pullout failure requires computing the reinforcement embedment length. Therefore, the location of failure plane is an important input for this design. The current FHWA MSE wall design guidelines assume the location of failure plane based on Rankine theory. While this assumption holds true for conventional walls it is unconservative for GRS walls under constrained spaces, also known as “narrow GRS walls”. This paper presents a limit equilibrium study to accurately locate failure planes within narrow GRS walls. The critical failure planes within narrow GRS walls are searched using Spencer’s method with a function of noncircular failure plane. The predicted results from limit equilibrium analyses are verified by the experimental data from centrifuge tests conducted on narrow GRS walls. The results indicate that the critical failure plane is bilinear: The failure surface being formed partially through the reinforced soil and partially along the interface between the GRS and the stable wall face. The results show the inclination angles of the failure planes for narrow GRS walls being 10~ 20 less than those calculated by Rankine theory. The effect of wall aspect ratio on the inclination angle of the critical failure plane is investigated for the cases studied in this paper. Design considerations against pullout failure for narrow GRS walls are also discussed at end of this paper.