Pseudo-Static Seismic Analysis Of Geosynthetic-Reinforced Segmental Retaining Walls

Abstract

The paper examines seismic stability analyses of geosynthetic-reinforced segmental retaining walls (modular block walls). Stability analyses are developed within the framework of a pseudo-static approach that gives factors of safety against collapse mechanisms or rupture of component materials. The Mononobe-Okabe method is used to estimate dynamic earth pressures. Parametric analyses of forces and factors of safety related to external, internal and facing failure modes for walls constructed on competent foundations are presented. Shear interfaces between facing units are considered as possible planes of failure in facing stability analyses. The potential for local toppling of the facing column is also investigated. The results of analyses demonstrate that there is a limiting value of the horizontal seismic coefficient above which the margin of safety against base sliding and overturning may be unacceptably low during a seismic event for segmental retaining walls designed to just satisfy minimum factors of safety under static loading conditions. Pseudo-static seismic analyses of the performance of two geosynthetic-reinforced segmental walls during the Northridge Earthquake in Los Angeles in 1994 are demonstrated to be consistent with visual observation of tension cracks in the soil backfill. Limitations of pseudo-static methods are discussed and recommendations for further research are made.