ABSTRACT
Transitions between geological/geotechnical soil units have a critical impact on the operation and performance of a tunnel boring machine (TBM). In the current industry practice, deterministic profiles are relied on, and the possible locations of transitions are not quantified. This paper investigates into the efficacy of geostatistics to quantify the uncertainty in soil transitions. The results presented herein validates that information entropy, a metric to quantify uncertainty in categorical units (soil/rock units), is insufficient and misleading in quantifying the uncertainty of critical features, such as soil transitions. A geostatistics-based probabilistic modeling approach is presented to quantify the uncertainty in soil transition locations. The approach is applied on a soft ground tunnel project in North America and results are validated using actual TBM data. The assessment enhances the confidence in using geostatistics to improve ground awareness for efficient tunnel construction, minimizing different site condition (DSC) claims, and improving decision-making on tunnel projects.
