Coevolution of Rock Slope Instability Damage and Resonance Frequencies From Distinct‐Element Modeling

Abstract

AbstractAmbient vibration measurements can detect resonance frequency changes related to rock slope instability damage or boundary condition changes during progressive failure. However, the impact of slope kinematics on resonance changes and the expected form and sensitivity of frequency evolution during destabilization require clarification to improve the implementation of this technique across diverse settings. Since instrumented rock slope failures are rare, numerical modeling is needed to study the anticipated spectral response from in situ monitoring. We used 2D distinct‐element modeling to evaluate the sensitivity and evolution of rock slope resonance behavior for slab toppling, flexural toppling, and planar sliding instabilities during progressive failure. Model simulations revealed that fundamental resonance frequency decreases between 20% and 60% with changes correlated with increasing length of open joints. Changes to higher‐order frequencies associated with landslide sub‐volumes were also detectable for cases with multiple fracture networks. Resonance behavior was most pronounced for failures dominated by steeply dipping open tension cracks, that is, flexural and slab toppling. Additionally, amplification patterns across the slope varied for the flexural toppling and sliding cases, providing potential new information with which to characterize landslide failure mechanisms using ambient vibration array measurements. Our results demonstrate landslide characteristics well‐suited for in situ ambient resonance monitoring and provide new data describing the anticipated changes in resonance frequencies during progressive rock slope failure.