Date of Award

Fall 2024

Project Type

Dissertation

Program or Major

Civil and Environmental Engineering

Degree Name

Doctor of Philosophy

First Advisor

Jean Benoît

Second Advisor

Majid Ghayoomi

Third Advisor

Julie Paprocki

Abstract

This doctoral research investigates rockfall movement under laboratory and field-controlled conditions as well as in situ natural field environments in an effort to better understand the movement described by falling blocks. Although previously published research identified several factors that affect rockfall movement (block characteristics, ground characteristics, and impact kinematics), the lack of a standardized methodology to evaluate rockfall behavior upon impact on different ground materials increases the difficulty of establishing realistic parameters in modeling approaches and ultimately in selecting representative model input parameters. In order to measure rockfall movement under different test conditions, concrete fabricated test blocks ranging in mass from 1 to 107 kg were instrumented with Smart Rock (SR) sensors in their center of gravity to measure acceleration and rotation during rockfall experiments. A total of 310 drop tests under controlled conditions evaluated provided SR outputs coupled with high-speed videos, which could be used to assess rockfall behavior and kinematics at and after impact on different ground surfaces, prepared at different slope angles. As part of this research, a new ground characterization methodology using a Portable Measurement While Drilling (PMWD) device provided several profiles of ground resistance to drilling over depth. Based on these characterization tests with the PMWD and a lightweight dynamic cone penetrometer, ground surfaces were classified into soft, medium, and hard categories for subsequent use in numerical modeling. The proposed ground classification was compatible with a new methodology to evaluate the impacted ground based only on SR measurements. Results demonstrate the complex nature of kinematic motions upon impact, and initial model comparisons reproducing the controlled test conditions highlight the difficulty with model input parameter selection and demonstrate the importance of accurately accounting for actual motion during impact in model estimates. Additionally, field rockfall and subsurface characterization experiments performed in two sites of different topography and geology were carried out to validate findings from controlled tests and assess model predictions from lumped mass and rigid body approaches of three existing modeling software. A comparison between model simulations and the experimental results highlighted the primary limitations of models and was used to propose recommendations for the improvement of the use of existing methods. This research contributes to a deeper understanding of rockfall behavior and provides recommendations for enhancing existing rockfall modeling approaches.

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