Geological discontinuity persistence: Implications and quantification

Abstract

Persistence of geological discontinuities is of great importance for many rock-related applications in earth sciences, both in terms of mechanical and hydraulic properties of individual discontinuities and fractured rock masses. Although the importance of persistence has been identified by academics and practitioners over the past decades, quantification of areal persistence remains extremely difficult; in practice, trace length from finite outcrop is still often used as an approximation for persistence. This paper reviews the mechanical behaviour of individual discontinuities that are not fully persistent, and the implications of persistence on the strength and stability of rock masses. Current techniques to quantify discontinuity persistence are then examined. This review will facilitate application of the most applicable methods to measure or predict persistence in rock engineering projects, and recommended approaches for the quantification of discontinuity persistence. Furthermore, it demonstrates that further research should focus on the development of persistence quantification standards to promote our understanding of rock mass behaviours including strength, stability and permeability.

Geostructural and Geomechanical Study of the Piastrone Quarry (Seravezza, Italy) Supported by Photogrammetry to Assess Failure Mode

“…Pre-existing discontinuities and their orientation, in relation with the orientation of excavation, determines the possible kinematic instability mode: some case studies regarding different kinds of quarry are reported in [38][39][40][41]. Stability conditions are further affected by discontinuity persistence in the form of rock bridges that can increase the available shear resistance [42][43][44]. Finally, the volume of detachable rock block is determined by spacing of rock joints.…”

The Arsenic Fault-Pathfinder: A Complementary Tool to Improve Structural Models in Mining

“…In mining operations, the precise determinations of relevant fault geometries oriented to geotechnical design are a major concern for structural geologists and geotechnical engineers [1][2][3][4][5]. The principal uncertainties in structural and geomechanical models are mainly controlled by both limited data collection resolution [6] as well as the spatial distribution of data.…”

“…Thus, in practice, mining engineers must complete large interpretations during complex structural modeling by using software that can build multiple data-consistent solutions. This scenario has strong consequences in the mining value chain [5,7] affecting not only the geotechnical design, but also the hydrological management, blasting strategies, among others. Additionally, the transition in the mining operation from open-pit to the underground, i.e., OP to UG transition [8,9], triggers a requirement to improve the quality and precision of the structural and geomechanical models for an in-depth mining for hard rock masses (i.e., volcanic rocks) in which brittle slope failures are difficult to predict [7].…”

“…Additionally, the transition in the mining operation from open-pit to the underground, i.e., OP to UG transition [8,9], triggers a requirement to improve the quality and precision of the structural and geomechanical models for an in-depth mining for hard rock masses (i.e., volcanic rocks) in which brittle slope failures are difficult to predict [7]. In the subsurface, geological discontinuities are usually complex and their full characterization is a concern to be still investigated [5]. This is the main challenge for geological and mine engineers in current mining and requires considering an entire and comprehensive geological description of an ore deposit.…”

“…This is the main challenge for geological and mine engineers in current mining and requires considering an entire and comprehensive geological description of an ore deposit. In this way, geophysical techniques have been used to investigate structural attributes in the subsurface [5,10] and to propose the 3-D internal structure of a rock mass [10]. To our knowledge, this contribution represents the first approach to characterize fault attributes in the 3-D space using geochemical mine data.…”