Degree
Doctor of Philosophy (PhD)
Department
Department of Civil and Environmental Engineering
Document Type
Dissertation
Abstract
Existing plasticity solutions for modeling cavity contraction problems, particularly for models with inherent singularity such as Hoek-Brown and Mohor-Columb models are often approximate and incomplete, leading to inaccurate prediction of the stresses in some cases and in absence of viable solutions in others. This study develops a series of rigorous semi-analytical solutions for evaluating the stresses of contracted cavities for two types of elastoplastic constitutive models encountered in the wellbore drilling and tunnel excavation: the perfectly plastic nonlinear Hoek-Brown failure criterion and the linear strain hardening Mohr-Coulomb criterion. Using the newly developed graphical method by Chen & Abousleiman (2023), this study thoroughly analyzes the stress response and behavior around cavities. The graphical analysis identifies nine distinct stress behavior scenarios, of which only one has been previously addressed in the literature. Moreover, the existing solutions for this scenario suffer from four major limitations: excluding the corner loading case, the hydrostatic assumption, the intermediacy assumption, and the small strain assumption. To resolve this gap in literature, new equations are derived to address the remaining eight unexplored scenarios, providing a more comprehensive understanding of cavity contraction mechanics. The proposed solutions successfully overcame the previously mentioned limitations found in the literature. The derived equations are used to obtain cavity curves, and the pore pressure curves across a range of parameters related to the constitutive models and different values of the coefficient of earth pressure at rest K_0. The results highlight the limitations of the existing solutions to capture the full stress behavior around contracted cavities and demonstrate the new solution capability to accurately predict stresses. Beyond its theoretical contributions, the proposed solution has significant engineering applications, particularly in accurately predicting the critical mud pressure required to maintain wellbore stability.
Date
4-3-2025
Recommended Citation
Abu Dayyeh, Hadeel, "GRAPHICAL ANALYSIS-BASED SOLUTIONS FOR CAVITY CONTRACTION PROBLEM IN ELASTOPLASTIC GEOMATERIALS WITH CORNER SINGULARITY" (2025). LSU Doctoral Dissertations. 6758.
https://repository.lsu.edu/gradschool_dissertations/6758
Committee Chair
Dr. Sheng-Li Chen