Numerical study on failure and instability of slender rock columns: Synergistic effects of lateral pressure, height-to-width ratio, and material strength

• Published in: Deep Resources Engineering Vol. 2; no. 2; p. 100185
• Main Authors: Feng, Shiguo, Li, Gen
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2025
• Subjects: H/W ratio; Lateral pressure; Material failure; Material strength; Slender rock column; Structural instability; Material failure; H/W ratio; Slender rock column; Lateral pressure; Structural instability; Material strength
• ISSN: 2949-9305; 2949-9305
• DOI: 10.1016/j.deepre.2025.100185

Columnar jointed rock mass (CJRM) combines and mosaic of slender rock columns with different height-to-width (H/W) ratios. Revealing the correlation of the mechanical behavior of individual rock columns with internal factors (H/W ratio and material strength) and external factor (lateral pressure) is fundamental to understanding the deterioration of CJRM. We adopt a numerical scheme that combines a statistical meso-damage constitutive model with a finite element formulation based on finite deformation, which can simultaneously consider both material failure and structural instability of the rock columns. Compression tests of rock columns with different H/W ratios and material strengths under varying lateral pressures were conducted to analyze the macro-strength features and failure modes. The numerical results show that increasing the material strength can improve the macro-strength, while the effect of H/W ratio is the opposite. Both increases can promote the conversion of failure modes, and the evolution process is as follows: material failure-induced structural instability → synergy and competition between material failure and structural instability → structural instability-induced material failure. Notably, for the last failure mode, an increase in lateral pressure decreases the macro-strength of the rock column and heightens its instability risk. This finding provides new insights into the response of rocks with different H/W ratios under lateral pressure, extending beyond traditional material-based perspectives. According to the position of the failure mode demarcation line, the failure mode of the rock column can be regulated. •Studying the mechanical behavior of individual rock columns with internal and external factors is fundamental to understanding the deterioration of columnar jointed rock mass.•A unified finite element numerical scheme is adopted based on statistical meso-damage constitutive mode and finite deformation.•The macro-strength and failure modes of slender rock columns under different height-to-width ratios, material strengths, and lateral pressures are investigated.•Increased lateral pressure can decrease macro-strength and heighten instability risk for rock columns of structural instability-dominated mode.