ERI: Identifying Seismically-induced Failure Mechanisms in Homogenous Rock Slopes

University Of Washington, Seattle WA

Investigators

Abstract

This Engineering Research Initiation (ERI) award supports research aiming to explain the fundamental behavior of homogenous rock slopes during earthquakes. In this study, homogenous refers to modeling of the rock mass without explicitly defined pre-existing discontinuities. The study will investigate the initiation and growth of fractures within the rock slope and earthquake and slope characteristics controlling the failure mechanisms. Identifying the dynamic stresses that lead to failure initiation will enhance our knowledge of how seismic waves interact with slope geometries to induce rupture in the rock mass. This work will enable a new understanding of the factors contributing to rock slope failures during earthquakes by quantifying the triggering thresholds associated with different failure mechanisms. This understanding will enhance engineers' ability to perform regional-scale hazard analysis in seismic hazard areas with rock slopes. Regional hazard analysis can improve the safety and well-being of individuals in populated areas with hazardous rock slopes by enabling designers and policy-makers to make data-informed decisions about hazard risk and mitigation associated with this phenomenon, thus saving lives and preserving critical infrastructure economic investments. The research in this study will be complemented by developing outreach materials focused on engaging middle and high school students in civil engineering. The goals of this study are to identify the dynamic stress state characteristics leading to the initiation and failure of homogeneous rock slopes, identify the combinations of ground motion characteristics, rock mass properties, and slope geometries that lead to those critical stress states, and develop and test a predictive framework for predicting co-seismic rock slope performance. Rock slope dynamic stress states, fracture initiation, propagation, and coalescence will be modeled using a subset of the discrete element method called the bonded particle model. The dynamic implementation of the bonded particle model can capture wave transmission, reflection, and absorption at boundaries. The study will extend previous dynamic bonded particle model capabilities by calibrating the softening bond model, which captures a broad range of brittleness ratios for dynamic simulation. A systematic study of the dynamic stress state characteristics leading to initiation of failure of intact rock mass slopes and subsequent slope performance will be used to develop the predictive framework. The ability of the framework to predict real-world coseismic rock slope performance will be evaluated through comparison to well-documented case histories of rock slope failures. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.