Investigation of seismic behavior of cantilever retaining walls considering soil-structure interaction and different wall geometries

Retaining walls are special engineering structures that are used in many applications of Civil Engineering with many different goals. Highways embankments, in which a significant amount of earthwork is required, canals and water tanks, bridge abutments, material depository fields, and erosion and flood control are some of the most common engineering applications where retaining walls are used. Determination of behavior of retaining walls under different soil conditions and loading cases, and evaluation of their behavior prior to design are of critical importance. Moreover, in the countries located in active earthquake zone such as Turkey, in addition to the determination of static behavior, determination of the dynamic behavior of retaining walls which are used for many engineering fields is also important. In general, seismic analysis and design of retaining walls are carried out with pseudo static approaches based on Mononobe-Okabe method. Seismic soil pressures acting on retaining walls are obtained using the equilibrium of forces on the soil wedge behind the retaining wall by means of Mononobe-Okabe method. Wave propagation effects and soil-structure interaction are not considered in this method. However, the interactions of retaining walls with backfill and foundation soil, and wave propagation effects convert the earthquake behaviors of these structures into a rather complex problem. The main purpose of this study is to investigate seismic behavior of backfill-cantilever retaining wall-foundation/soil systems under different ground motions considering soil-structure interaction and different wall geometries. In line with this aim, seismic analyses based on finite element method in time domain were carried out considering four different foundation soil conditions, three different wall geometries, and two different earthquake ground motions. In the analyses, North-South component of the 1999 Kocaeli Earthquake recorded in Yarimca station, and HSP000 component of the 1989 Loma Prieta Earthquake recorded in Hollister-South & Pine station were taken into consideration. The study consists of three chapters. In the first chapter, general information about retaining walls, nonlinear behavior of materials, soil-structure interaction, and the aim and scope of the study are presented. In the second chapter, the numerical models proposed for backfill-cantilever retaining wall-foundation/soil systems are introduced, and dynamic analyses of these systems are fulfilled. In the third chapter, conclusions obtained from the study and suggestions are given. This chapter is followed by references list and autobiography. Finally, in this study, it was seen that the seismic behavior of cantilever retaining walls can change significantly depending on soil-structure interaction, wall geometry and earthquake frequency content. It was also determined that wall section and soil interaction can affect the magnitude of the dynamic soil pressures acting on the wall. In this connection, it can be stated that these effects should be taken into consideration in design process for realistic and reliable design. Key Words: Cantilever Retaining Wall, Earthquake Frequency Content, Finite Element Method, Seismic Behavior, Soil-Structure Interaction, Wave Propagation