Load redistribution rules for progressive failure in shallow landslides: Threshold mechanical models

Rainfall‐induced landslides are often preceded by progressive failures that culminate in abrupt mass release. Local failure progression is captured by a landslide hydro‐mechanical triggering model that represents the soil mantle as interacting columns linked by tensile and compressive mechanical “bonds.” Mechanical bonds may fail at a prescribed threshold leaving a modeling challenge of how to redistribute their load to neighboring intact soil columns. We employed an elastic spring‐block model to analytically derive redistribution rules defined by the stiffness ratio of compressive to tensile bonds. These linear‐elastic rules were generalized to real soil using measurable Young's modulus and Poisson's ratio. Results indicate that “local” failure characteristics of ductile‐like soils (e.g., clay) are reproduced by low stiffness ratios, whereas “global” failure of brittle sandy soils corresponds to large stiffness ratios. Systematic analyses yield guidelines for selecting load redistribution rules for failure of geological materials and mass‐movement phenomena represented by discrete threshold‐mechanics.