Simulating the catastrophic acceleration of creeping landslides with critical state plasticity

Document Type

Article

Publication Date

6-4-2026

Abstract

Slow-moving landslides display varying rates of motion throughout their lifetime. Since such motion may manifest without apparent external forcing, it is often referred to as landslide creep. In extreme cases, creep-like movements develop at rapidly increasing rates, a phenomenon referred to as tertiary creep (i.e., accelerating, catastrophic motion). Our manuscript aims to explore the causes of such forms of unstable creep-like motion by using principles of critical state soil mechanics. For this purpose, a computationally efficient framework to simulate the coupled hydromechanics of creeping landslides is proposed. Our model allows for a versatile choice of the constitutive law controlling shearing and excess pore-water pressure buildup/dissipation in the basal shear zone of landslides, as well as for a double diffusion process capturing how rainfall elevates the basal pore pressure levels. We show that by describing the inelastic deformation of the landslide base through a simple shear model inspired by Modified Cam Clay, the framework recovers naturally both steady episodic seasonal motion (here referred to as secondary creep) and unstable accelerating motion (i.e., tertiary creep). The approach of catastrophic failure is explained in terms of critical state conditions and, consequently, of the vanishing of the dilative effects that would otherwise regulate the rate of motion by preventing it from growing uncontrollably. Our proposed approach is tested against real cases, confirming that the model can capture spontaneous acceleration without external forcing by virtue of its ability to modulate the basal shearing resistance as a function of the competition between the rates of softening, excess pore pressure dissipation, and volume change. The presented model provides a unified, computationally efficient framework capable of capturing both prolonged slow movement and catastrophic acceleration.

Publication Title

Engineering Geology

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