Affiliation:
1. Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada.
Abstract
Knowledge of in situ stress magnitude and orientation plays a very important role in geological/geotechnical engineering and in the development of energy resources, such as caprock integrity, waste fluid disposal, geological storage of CO2, and geothermal energy extraction. The uncertainty of estimated parameters, especially horizontal stress, from in situ tests such as pressuremeter tests is a long-standing challenge owing to the existence of uncertainties from geomaterial spatial variability, measurement errors, limited information, and modelling methods. Therefore, non-unique solutions are often encountered in pressuremeter interpretation. In this study, a statistical inverse analysis method is proposed to solve this issue by combining a closed-form solution, finite-difference model, and selected optimization algorithms. The objective of the statistical inverse analysis is to determine the optimal parameters by minimizing the sum of squared errors while providing the confidence intervals of inversed parameters. Random variables generated in the optimization process reproduce the potential parameter uncertainties. The Jacobian matrix and confidence intervals are derived from the optimization process to evaluate variability of the predicted horizontal stress and ground properties. A workflow is presented that demonstrates a statistical inverse method for analyzing pressuremeter results and helps quantify uncertainties of the ground properties and in situ stress magnitudes and orientations derived from a pressuremeter test.
Publisher
Canadian Science Publishing
Subject
Civil and Structural Engineering,Geotechnical Engineering and Engineering Geology
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