Empirical predictive relationships for rigid sliding displacement based on directionally-dependent ground motion parameters

- The rigid sliding displacements are computed for ground motions at all orientations.
- The distribution of sliding displacements in various orientations is examined.
- Predictive relationships for orientation-independent displacement are provided.
- The proposed relationship considers the effects of ground motion directionality.

The seismic performance of earth slopes is typically quantified by the predicted rigid-sliding-block displacement of a simplified sliding mass. Current empirical predictive relationships for earthquake-induced sliding displacements of slopes are generally developed based on the computed displacement data from a suite of earthquake ground motion time histories. The displacement predicted from these relationships is for the ground motion intensity measures associated with a specific ground motion time history. These intensity measures are different from those for a single definition of bidirectional ground motion that are used in ground motion prediction equations and the distribution of ground shaking following an earthquake (e.g., ShakeMap), which take into consideration ground motion directionality. Therefore, the use of ground motion intensity measures is not consistent throughout the assessment process of seismic sliding displacement of slopes. This paper presents rigid sliding displacements calculated for a set of ground motion records by rotating the horizontal components through all angles. The degree of the azimuthal variation of sliding displacement of slopes with different yield accelerations is examined by analyzing the distribution of sliding displacements in all orientations. Empirical predictive relationships for the orientation-independent earthquake-induced sliding displacement of slopes are developed as a function of directionally-dependent definitions of ground motion parameters. The proposed relationships ensure consistency between the derivation of the ground motion intensity measures and its application in the prediction of sliding displacement of slopes, and consider the potential effects of ground motion directionality on displacement predictions.