Incorporating Deep Foundations in Limit-Equilibrium Slope Stability Analyses: Revisiting Fundamentals and Seismic Applications-PPT Presentation

PPT Presentation

Pdf Summary

The presentation reviews the mechanics of slope-stabilizing piles and introduces their application to seismic slope movements, particularly liquefaction-induced lateral spreading.<br /><br />For limit-equilibrium slope stability analysis, a pile’s resistance should reflect the pile–soil interaction limit state that occurs first—not automatically its structural shear strength. Depending on conditions, flow-around or flexural failure may precede shear failure; deep slides can produce substantial bending demands. A Crookston, Minnesota, case study showed that drilled shafts were far from shear failure when the slope failed, while flexural failure or displacement-related serviceability could control. The presenter therefore cautions that using pile shear strength directly in slope-stability calculations may be unconservative and recommends laterally loaded pile analysis to establish appropriate resistance.<br /><br />The seismic section discusses the limitations of limit-equilibrium methods for weak layers, where large seismic forces may combine with low shear strength and a small base-parallel component of slice weight. It outlines an equivalent-static analysis framework involving soil layers, drilled shafts, p-y springs, and bridge structures. Additional topics include accounting for pile resistance across the out-of-plane extent of lateral spreading, pile pinning, compatible displacement methods, and pile-head boundary conditions and their interaction with the superstructure.

Keywords

slope-stabilizing piles

seismic slope movements

liquefaction-induced lateral spreading

limit-equilibrium analysis

pile-soil interaction

flexural failure

drilled shafts

lateral spreading

p-y springs

bridge structures