Rigid Retaining Walls Subjected to Real Ground Motions

What is it about?

The design of retaining structures under the action of an earthquake is still an evolving art. Some theoretical calculation methods are available in literature but are limited. Many aspects are omitted such as types and effects of characteristics of the input motion, non-linearity of soils, the interaction between foundation and backfill. In recent years, numerical analyses, using finite element or finite difference methods, have been used for studying the seismic response of earth retaining walls. They have proved to be helpful tools when inhomogeneous soil conditions, non-linear behavior of backfill, an interaction between foundation and backfill and realistic input earthquake motion, must be considered.

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Why is it important?

Numerical analyses were performed by two dimensional explicit FLAC2D finite difference code. Various sets of real data (forty accelerograms) are used to assess dynamic response for different earthquake scenarios. 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 from 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.

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