CAREER: Decoding Jointed Rock Slope Failures across Multiple Scales: The Role of Natural Fractures and the Rock Matrix

About This Grant

This Faculty Early Career Development (CAREER) award funds research that intends to intends to identify and quantify factors contributing to the instability of jointed rock slopes. Rock slope failures pose significant risks to lives, infrastructure, and economies. These slopes are made of structured rock masses, which include intact rock blocks (rock matrix) intersected by natural fractures. Predicting the stability of such slopes is difficult due to the complex interactions between the rock matrix and natural fractures. Traditional models often oversimplify these interactions, averaging properties of the rock mass, failing to account for the distinct roles of the rock matrix and natural fractures in instability, and thus overestimating the safety margins and leading to inadequate risk assessments. This project seeks to advance fundamental knowledge of how the properties and degradation rates of the jointed rock components ‒ i.e., natural fractures and the rock matrix ‒ influence the instability of jointed rock slopes to improve predictive models and contribute to the safety and sustainability of infrastructure in mountainous regions. Other broader impacts include engaging students of different ages and the general public in innovative STEM outreach activities, such as inquiry-based problem-solving techniques for high school students, the Youth-in-Custody program participants, and visitors of natural history museums and mountainous national parks, to inspire public appreciation for civil and geotechnical engineering. Graduate and undergraduate students look to develop science communication skills through the design and delivery of educational and outreach activities. Each activity will be evaluated for its effectiveness in increasing enrollment in the regional civil engineering schools and the effects of inquiry-based activities on the public’s perception of engineering. The project is expected to expand participation in STEM fields and foster partnerships between universities, national parks, and local communities. The research looks to integrate laboratory experiments and numerical simulations to reveal the mechanisms driving fracture evolution and progressive failure processes in jointed rock slopes. The results seek to quantify the consequences of jointed rock failure, such as failing rock volume, runout distance, and velocity. The distinct contributions of the rock matrix and natural fractures to slope stability and the factor of safety look to be characterized based on the contrast between the hydraulic and mechanical properties of these components and the geometric characteristics of the slope relative to the natural fracture network. Experimental studies seek to simulate fracture-matrix interactions at various scales by monitoring the evolution of strain and fractures on the surface and through rock blocks and joints using high-spatiotemporal process monitoring techniques, such as digital image correlation and acoustic emission measurements. Scaled jointed rock slopes will be constructed in the laboratory using metal-ceramic 3D-printed rock blocks, with elevated gravity achieved by applying a strong magnetic field. Hydromechanically coupled, hybrid continuum-discontinuous numerical models will be calibrated and validated with experimental results with the intent of extending scenarios of the effects of contrasting hydromechanical properties and strength degradation rates on the instability of jointed rock slopes. These models seek to provide insights into strain and water pressure distribution effects on failure progression in full-scale jointed rock slopes. This project is expected to advance the state of the art in rock mechanics and slope stability analysis, improve infrastructure safety, and foster an informed STEM workforce through cutting-edge research and education. 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.