Lateral spreading within a limit equilibrium framework: Newmark sliding blocks with degrading yield accelerations

Lateral spreading is a prevalent geotechnical problem associated with earthquake-induced liquefaction, often occurring at gentle slopes of loose, saturated sand near bodies of water and causing significant damage to buried utilities. This study presents a deterministic approach to analyse lateral spreading behaviour using a modified Newmark analysis applied to a column of sliding blocks with degrading yield accelerations. The proposed sliding column approach exhibits reasonable agreement with a well-instrumented centrifuge test evaluating free-field lateral spreading. The analysis captures lateral spreading displacement throughout a soil profile, as well as shear strains and simplified earth pressures. The effect of light cementation is investigated, demonstrating notable arrest of lateral spreading displacements and pressures. Free-face effects are also evaluated for a liquefying layer of soil beneath a gentle, competent crustal slope, demonstrating notable lateral spreading behaviour with larger inclinations of liquefying soil. However, lateral spreading still occurred when considering a horizontal liquefying layer, realised due to inertial loading and differences between confining boundary forces. The approach can be utilised to efficiently analyse lateral spreading across a large spatial extent.