Quantifying the Rock Damage Intensity Controlled by Mineral Compositions: Insights from Fractal Analyses

Abstract

Since each rock type represents different deformation characteristics, prediction of the damage beforehand is one of the most fundamental problems of industrial activities and rock engineering studies. Previous studies have predicted the stress–strain behaviors preceding rock failure; however, quantitative analyses of the progressive damage in different rocks under stress have not been accurately presented. This study aims to quantify pre-failure rock damage by investigating the stress-induced microscale cracking process in three different rock types, including diabase, ignimbrite, and marble, representing strong, medium-hard, and weak rock types, respectively. We demonstrate crack intensity at critical stress levels where cracking initiates (σci), propagates (σcd), and where failure occurs (σpeak) based on scanning electron microscope (SEM) images. Furthermore, the progression of rock damage was quantified for each rock type through the fractal analyses of crack patterns on these images. Our results show that the patterns in diabase have the highest fractal dimensions (DB) for all three stress levels. While marble produces the lowest DB value up to σci stress level, it presents greater DB values than those of ignimbrite, starting from the σcd level. This is because rock damage in ignimbrite is controlled by the groundmass, proceeding from such stress level. Rock texture controls the rock stiffness and, hence, the DB values of cracking. The mineral composition is effective on the rock strength, but the textural pattern of the minerals has a first-order control on the rock deformation behavior. Overall, our results provide a better understanding of progressive damage in different rock types, which is crucial in the design of engineering structures.

Fractal analysis to determine JRC on sandstones and its correlation to SRF, Ende-Lianunu Regency, East Nusa Tenggara Province, Indonesia

“…The larger the grain size, the rougher the rock surface profile. It can be concluded that high fractal dimension values will be owned by materials with coarse grain size, but it does not apply to materials with uniform grain shape [33]. The fractal dimension provides a distinct quantitative approach to describe surface roughness that can be characterized qualitatively.…”

Fractal-Based Pattern Quantification of Mineral Grains: A Case Study of Yichun Rare-Metal Granite

“…Fractal and multifractal methods have been shown to be effective in delineating diverse complex geological patterns, as mentioned above; however, most studies have focused on recognizable macroscopic geometries, such as structures, geophysical and geochemical anomalies, and ore-related evidence, while only a few contributions have employed fractal analyses for mineral pattern characterization at the microscopic scale. Notably, mineralogical research has long been considered fundamental for ore-forming systems, while fractal-derived indices are quite suitable for characterizing the main targets of mineralogical studies, including but not limited to morphological descriptions [30], micro-structures [31], compositional variance [32,33], special textures [29] and mineral staging [13]. The microscopic information extracted from these fractal indices and their underlying scaling properties of mineral patterns can be utilized to trace the footprints of pattern-forming geological processes, which are crucial to understanding mineralization and/or diagenetic systems [34,35].…”

Study on Uniaxial Compression Deformation and Fracture Development Characteristics of Weak Interlayer Coal–Rock Combination

“…Zhang Heng et al [7] introduced the failure form of coal and gangue composite structures and explored the precursor signal characteristics of failure and instability of coal and gangue composite structures under an unloading path. Guo Weiyao et al [8][9][10] simulated uniaxial and biaxial compression tests of a coal-rock composite specimen with different coal-rock strength ratios and height-diameter ratios by using PFC2D 5.0 particle flow software. Wu Genshui et al [11] carried out research on the influence of coal-rock mass structure and fracture on the stability of a coal-bolt composite system and carried out experimental analysis and theoretical verification on the RCB composite system at different angles.…”