Enhanced Laboratory Testing and Characterization Related to the Mechanics of Anisotropic Rock

Geological engineering is a complicated field to practice in, especially when engineering solutions have to be designed to interact and sometimes be hosted in anisotropic geomaterials. This anisotropic environment is composed of two components, discontinuities and intact blocks. In many cases, these intact blocks of rock are anisotropic, specifically transverse isotropic, where empirical methods do not accurately predict behaviour and analytical solutions are not always available, leaving numerical methods to help predict their behaviour. As civil infrastructure continues to be built in increasingly complex rockmasses at greater depths, it is important to use testing methods measuring geomechanical properties with a high degree of accuracy and repeatability. Tensile strength is commonly measured via the indirect tensile strength test, intact elastic components and compressive strength are measured via the unconfined compressive strength test, and joint deformation is measured via the direct shear test. However, the testing methods were historically designed for rock materials that were homogenous and isotropic. This research addresses the limitations of some of the most common laboratory testing methods used in rock engineering design and proposes modifications to the testing methods, as well as recommendations for instrumentation and guidelines for data processing. For joint stiffness this thesis recommends that an intact control specimen be tested to account for both machine and system deformations. In order to quantify joint roughness, a method using Structure-from-Motion photogrammetry and statistical analysis is proposed to understand the anisotropic behaviour of joint surfaces. For tensile strength testing, it is recommended that specimens be instrumented to measure strain and determine strain thresholds in order to measure crack initiation as well as confirm proper loading. For anisotropic tensile strength, a new three-part failure criterion based on stress transformation mechanics is proposed, and validated using digital image correlation. For compressive loading, recommendations for the use of dynamic elastic constants are presented as an alternative to static measurements which typically have a high degree of scatter. Finally, a new behaviour model is presented for anisotropic materials suggesting the onset of two crack initiation points: shear along foliation and tensile fracturing in the matrix.

Department dc:contributor.department

Geological Sciences and Geological Engineering

Year dc:date.issued

2024

Author dc:creator

• Packulak, Timothy

Advisors dc:contributor.supervisor

• Diederichs, Mark
• Day, Jennifer

• Laboratory Testing
• Anisotropic Geomaterials
• True Tensile Strength
• Joint Stiffness
• Structure from Motion Photogrammetry
• Joint Roughness
• Unconfined Compressive Strength
• Brazilian Tensile Strength

Statement dc:rights

• Attribution-NonCommercial-ShareAlike 4.0 International

Licence dc:rights.uri

• http://creativecommons.org/licenses/by-nc-sa/4.0/

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1974/32843

OAI identifier oai:identifier

oai:queensu.scholaris.ca:1974/32843