SEISMIC PERFORMANCE OF SLOPES IN PSEUDO-STATIC DESIGNS WITH DIFFERENT SAFETY FACTORS

Seismic coefficient values coupled with minimum pseudo-static safety factors are still
used for analysis where selection of seismic coefficients relies on expertise and judgment.
However, safety factor approach does not give any idea about the deformations and displacements
that are expected to occur during earthquake loading. Displacements are mostly evaluated by
equations based on yield acceleration of the slope and maximum acceleration of sliding mass. The
method based on rigid block gives co-seismic permanent slope deformation when its factor of
safety equals 1.0, hence, there is a need to link slope displacements, seismic coefficients and
pseudo-static safety factors. This will enable the designers to predict slope displacements based on
selected seismic coefficients. In the present paper, slope displacements obtained for different peak
ground accelerations and safety factors are used to propose charts linking co-seismic slope
displacements (D), seismic coefficients (􀝇􀯛) and pseudo-static safety factors (FS), which are
important parameters in pseudo-static approach. This enables the 􀝇􀯛 values to be chosen based on
allowable displacements instead of using judgment and expertise. Results show that 􀝇􀯛 values for
any allowable displacement should be based on anticipated PGA and FS values. Subsequently,
slope displacements are utilized in developing a novel displacement-based methodology to select
the seismic coefficient which will be used to calculate the pseudo-static safety factor.