Review of Studies on Retaining Wall's Behavior on Dynamic / Seismic Condition
Current theories, experimental investigations and numerical findings for retaining walls subject to dynamic excitations are reviewed. Brief features of each method, and experimental and numerical methods are introduced and compared. Tables are listed after each section for a clear and brief view of methods in a categorized manner. Conclusive comments plus current concerns and future expectations of this area are made at last. This review aims at shedding light on the development and concepts of different researches in dynamic retaining wall design and analysis.
Numerical Modeling of the Dynamic Behavior of Rigid Retaining Walls Subjected to Real Near-Fault Ground Motions and Estimation of Seismic Lateral Earth Pressures
In this study, a series of nonlinear 2D finite difference analyses were carried out to study the seismic behavior of non-yielding gravity-type earth retaining walls founded in rock site subjected to “Real Near-Fault ground motions”. Numerical analyses were performed by two dimensional explicit FLAC2D finite difference code. Various sets of real data (forty accelerograms) records were applied at the bedrock level to assess model’s dynamic response for different earthquake scenarios. All ground motions have a baseline correction and all output accelerograms obtained from the dynamic analyses are filtered using a non-causal bandpass filter of order 4, between 0.1 and 25 Hz. In these calculations, the foundation non-deformability, the seismic amplification or attenuation and the non-linearity of the soil placed behind the retaining wall are considered. We highlighted an important correlation between the PGA (Pic Ground Acceleration) calculated in free field (accounting for the wave propagation) and the obtained pressure. Numerical results are compared to theoretical calculation methods available in the literature. Among them, Wood's method seems to be the most precise one, presenting small deviations with the numerical methods. Moreover, it is the safest method, in the sense that it predicts the highest pressure values, not only in the elastic cases but even in some situations when non-linearity appears. In addition, we found that the time corresponding to the maximum calculated values of lateral earth pressure acting on the wall matches with the time of the calculated (PGAff). So, the main takeaway of this observation is the zero effect of seismic duration on pressure evolution.
Seismic Design of Gravity Retaining Walls
Abstract : The design of gravity retaining walls in an earthquake-prone environment is usually based upon static analysis using an equivalent seismic coefficient. This can be a suitable approach, provided that the seismic coefficient is determined from a rational analysis of actual dynamic behavior. The report discusses the seismic design of gravity walls retaining granular backfill without pore water. The general features of behavior are illustrated by field experiences, results from laboratory model tests and from theoretical analyses. Both the conventional method of design and the Richards-Elms method, based upon an analogy to a sliding block, are reviewed. A shortcoming of the sliding block analogy is discussed, and corrections obtained using a two-block model are presented. Several sources of uncertainty are examined in detail: the random nature of ground motions, uncertainty in resistance parameters, and model errors, including the important influence of deformability in the backfill. All of these results are then combined to develop a probabilistic method for predicting seismically induced displacements of walls and an improved version of the Richards-Elms method of design. The risk that walls designed by the conventional method might experience excessive displacements is analyzed. Originator supplied keywords include: Retaining walls--design and construction (LC); Richards-Elms retaining wall design method (WES).