Three-Dimensional Numerical Modeling of Grain-Scale Mechanical Behavior of Sandstone Containing an Inclined Rough Joint
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ORIGINAL PAPER
Three‑Dimensional Numerical Modeling of Grain‑Scale Mechanical Behavior of Sandstone Containing an Inclined Rough Joint Jin‑Zhou Tang1,2 · Sheng‑Qi Yang1 · Derek Elsworth2 · Yan Tao1 Received: 13 May 2020 / Accepted: 15 October 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract We intercompare highly constrained physical experiments with a three-dimensional bonded-particle discrete element model. The models incorporate a single inclined rough joint at various inclinations to simulate the mechanical response of fracturedrock from micro-scale cracking through crack-coalescence and culminating in macro-scale rupture. This approach combines the scanned 3D surface morphology of the real joints with a smooth-joint contact DEM model to overcome the problem of using a simplified geometry that cannot truly reflect the effects of joints on rock mass response. In both the physical samples and in the modeling, the inclination angle of the joint was varied between 0° and 50°, and the samples were tested under confining stresses in the range 0–40 MPa. The numerical test results indicate that: (1) confining stress has a significant strengthening effect on the jointed sandstone; (2) a threshold angle of ~ 40° of the inclined joint controls failure; (3) when the inclination angle is less than ~ 40°, failure is through the intact rock with some tensile fracturing around the joint and when greater than ~ 40° slip occurs on the joint with shear fracturing concentrated near the joint surface; (4) the 3D numerical approach replicates the deformation history and evolving texture of the jointed sample response with high fidelity, including the evolution of micro-scale features of progressive failure. The three-dimensional bonded-particle discrete element modeling represents a systematic verification of, and extension to, laboratory tests, presenting a viable model to emulate the mechanical behavior of jointed rocks with the potential to enhance the predictive capability of modeling while still maintaining reasonable computational efficiency. Keywords Rough joint · Strength · Failure modes · Micro-cracks · PFC3D
1 Introduction Rock masses often contain joints with their inclination and roughness representing key factors for the strength and stability of rock masses. Such joints provide planes of weakness that act as the locus for failure and displacement within rock masses as they impact structures on and in rock (Hoek 1983; Brady and Brown 2004; Brown 2004). Joints incorporate roughness across a spectrum of scales (Candela et al. 2009), * Sheng‑Qi Yang [email protected] 1
State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 221116, People’s Republic of China
Department of Energy and Mineral Engineering, EMS Energy Institute, and G3 Center, Pennsylvania State University, University Park, PA 16802, USA
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making representation in the laboratory problematic—as sampling scale i
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