Collaborative Research: Multi-Block System Response to Hydraulic Loads in Rock Scour

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 research uses joint flume and numerical modeling to establish a more comprehensive understanding of the mechanics of hydraulic plucking, which will inform infrastructure design and remediation. This mechanistic understanding of the governing modes of failure will make it possible to identify the most efficient design or remediation strategy, and can also be incorporated into landscape evolution models. The systematic means by which the multi-scale and progressive nature of plucking is explored will provide insights into key parameters that should be considered in real-time hazard analysis and landscape evolution. Additionally, software developed as part of this research will be released open-source to make it available to researchers and engineers. The experimental data set will also be stored in a public repository to be more broadly available and accessible. Accurately predicting the likelihood of plucking requires an understanding of how different properties of the fractured rock mass or engineered material interplay with flow characteristics of the fluid flowing over, around, and through it. It is not fully understood how variation in these properties influence plucking, nor is it considered in present scour evaluation methods, even though the potential stacking of effects could lower the threshold for scour. This research will develop capabilities that assess the interaction between different material and flow properties in order to develop a more comprehensive understanding of the plucking process. This will be achieved through a paired experimental and numerical approach that applies scaled flume experiments and coupled Discrete Element and Lattice Boltzmann Method numerical simulations. These capabilities will enable scour assessment methods that move away from empiricism by limiting the number and extent of simplifying assumptions that need to be made in physics-based models. The understanding of the underlying mechanics gained from this research and identification of the most critical features of the multi block-fluid system will inform further research applied to stability and remediation of engineered structures, as well as descriptions of rates of bedrock erosion in natural channels. 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.