CEE Seminar: Kinematics of Hydraulic Plucking in Fractured Rock

Abstract: Scour by hydraulic plucking is a fundamental process in landscape evolution where large, competent rock blocks are eroded from a fractured rock mass by flowing water. This process also affects engineered structures interacting with water, such as dams and bridges, and often leads to operational and safety concerns since erosion of large volumes of material can compromise structure foundations and serviceability. This presentation will highlight how this interaction between a blocky rock mass and water is analyzed by directly modeling the solid and fluid phases using a coupled Discrete Element Method (DEM) and Lattice Boltzmann Method (LBM) approach. The highly turbulent flow conditions at which plucking often occurs are modeled using Large Eddy Simulation implemented in the LBM. Results show that this modeling methodology is able to capture the correct kinematic failure mode in block removal in several scenarios without restricting the potential failure mechanism. This capability makes this scour assessment technique broadly applicable since site-specific characteristics can be directly incorporated in scour risk assessments.

Bio: Michael Gardner is an assistant professor at the University of Nevada, Reno, in the Department of Geological Sciences and Engineering. He received his bachelor's degree in civil engineering and his master's degree and doctorate in geotechnical engineering from UC Berkeley. Prior to pursuing his graduate studies, he worked as a geotechnical engineer in San Francisco and prior to attending university, he served in the U.S. Army as a combat engineer. His professional and research interests include geological engineering, rock mechanics, natural hazards engineering and the application of numerical and stochastic methods to shallow earth processes and engineering analysis.