The Influence of Healed Intrablock Rockmass Structure on the Behaviour of Deep Excavations in Complex Rockmasses
MetadataShow full item record
Conventional rockmass characterization and analysis methods for geotechnical assessment in mining, civil tunnelling, and other excavations consider only the intact rock properties and the discrete fractures that are present and form blocks within rockmasses. Field logging and classification protocols are based on historically useful but highly simplified design techniques, including direct empirical design and empirical strength assessment for simplified ground reaction and support analysis. As modern underground excavations go deeper and enter into more high stress environments with complex excavation geometries and associated stress paths, healed structures within initially intact rock blocks such as sedimentary nodule boundaries and hydrothermal veins, veinlets and stockwork (termed intrablock structure) are having an increasing influence on rockmass behaviour and should be included in modern geotechnical design. Due to the reliance on geotechnical classification methods which predate computer aided analysis, these complexities are ignored in conventional design. Given the comparatively complex, sophisticated and powerful numerical simulation and analysis techniques now practically available to the geotechnical engineer, this research is driven by the need for enhanced characterization of intrablock structure for application to numerical methods. Intrablock structure governs stress-driven behaviour at depth, gravity driven disintegration for large shallow spans, and controls ultimate fragmentation. This research addresses the characterization of intrablock structure and the understanding of its behaviour at laboratory testing and excavation scales, and presents new methodologies and tools to incorporate intrablock structure into geotechnical design practice. A new field characterization tool, the Composite Geological Strength Index, is used for outcrop or excavation face evaluation and provides direct input to continuum numerical models with implicit rockmass structure. A brittle overbreak estimation tool for complex rockmasses is developed using field observations. New methods to evaluate geometrical and mechanical properties of intrablock structure are developed. Finally, laboratory direct shear testing protocols for interblock structure are critically evaluated and extended to intrablock structure for the purpose of determining input parameters for numerical models with explicit structure.
URI for this recordhttp://hdl.handle.net/1974/15306
Request an alternative formatIf you require this document in an alternate, accessible format, please contact the Queen's Adaptive Technology Centre
Showing items related by title, author, creator and subject.
SHALLOW URBAN TUNNELLING THROUGH HETEROGENEOUS ROCKMASSES: PRACTICAL EXPERIENCE FROM SMALL SCALE TUNNELS IN CALGARY, ALBERTA AND THE INFLUENCE OF ROCKMASS LAYERING ON EXCAVATION STABILITY AND SUPPORT DESIGN Crockford, Anna (2012-09-26)Shallow excavations through variable rockmasses in urban centers present significant design challenges, whether considering small diameter tunnels for utilities or large span underground caverns. In designing shallow ...
Modelling of Hard Rockmasses with Non-Persistent Joints to Assess the Stress Induced Damage of Deep Excavations Vazaios, IoannisBrittle fracturing within low confinement environments is the dominant failure mechanism of hard rockmasses under high magnitude in situ stresses around underground excavations. With an emphasis on the behaviour of slightly ...
Improving Continuum Models for Excavations in Rockmasses Under High Stress Through an Enhanced Understanding of Post-Yield Dilatancy Walton, Gabriel (2014-12-17)In recent decades, the field of rock engineering has seen an increased use of numerical modelling tools to aid in the analysis and design of underground excavations. Although complex numerical methods have been developed ...