Morphologic Interpretation of Rock Failure Mechanisms Under Uniaxial Compression Based on 3D Multiscale High-resolution Numerical Modeling

Abstract

Multiscale continuous laboratory observation of the progressive failure process has become a powerful means to reveal the complex failure mechanism of rock. Correspondingly, the representative volume element (RVE)-based models, which are capable of micro/meso-to macro-scale simulations, have been proposed, for instance, the rock failure process analysis (RFPA) program. Limited by the computational bottleneck due to the RVE size, multiscale high-resolution modeling of rock failure process can hardly be implemented, especially for three-dimensional (3D) problems. In this paper, the self-developed parallel RFPA 3D code is employed to investigate the failure mechanisms and various fracture morphology of laboratory-scale rectangular prism rock specimens under unconfined uniaxial compression. The specimens consist of either heterogeneous rock with low strength or relatively homogeneous rock with high strength. The numerical simulations, such as the macroscopic fracture pattern and stressstrain responses, can reproduce the well-known phenomena of physical experiments. In particular, the 3D multiscale continuum modeling is carried out to gain new insight into the morphologic interpretation of brittle failure mechanisms, which is calibrated and validated by comparing the actual laboratory experiments and field evidence. The advantages of 3D multiscale high-resolution modeling are demonstrated by comparing the failure modes against 2D numerical predictions by other models. The parallel RVEbased modeling tool in this paper can provide an alternative way to investigate the complicated failure mechanisms of rock.

A micromechanical analysis of marble pulverization under quasi-static progressive cyclic loading

“…The increasingly greater damage suggests that the cyclic loading had gradually promoted micro-crack initiation and propagation. In Stage III, the damage degree increased rapidly when the loading stress exceeded 1.21 σc until rock rupture, when extensive micro-cracking and a coalescence of macro-cracks occurred (Li et al, 2014;Tang, 1997). Similar nonlinear damage variations were also observed in previous cyclic tests under different confining stresses (for granite) (Pei et al, 2019), loading rates (for red sandstone) (Meng et al, 2016), and loading paths (for rock salt) (He et al, 2018).…”

Comparison of advanced discretization techniques for image-based modelling of heterogeneous porous rocks

“…Initially, many of these contributions dealt with the effect of degradation and cracking evolution on the mechanical response of geomaterials. This was achieved using various techniques such as micromechanically-inspired models [1], discrete element modelling [2] or RVE computations [3]. Fluid transport properties and their link to cracking evolution were also scrutinized using micromechanically-inspired models [1] and multiscale techniques [4,5].…”

“…With the availability of the detailed 3D microstructural geometry, µCT also allowed feeding microstructural mechanical computations making direct use of the image information. Such observations were mostly used to feed 3D DEM simulations on sandstones at the RVE and at the sample scales [3]. Strength anisotropy was scrutinized in Berea sandstone together with an µCT assessment of the porosity levels to feed 2D DEM simulations [16].…”

Study on Rockburst Nucleation Process of Deep-Buried Tunnels Based on Microseismic Monitoring

“…The code can thus determine the spatial distribution of seismic sources (acoustic emissions) during progressive failure of an advancing tunnel that are caused by material heterogeneity and produce nonlinear behavior. The RFPA code can also simulate and reproduce the entire process of rock failure from microscopic damage to macroscopic instability [38]. Figure 12: the model size is 150 m × 120 m; the excavation radius is 6.5 m; number of elements is 600 × 480 = 288,000; the width of the weak structural plane is 0.25 m; the angle between structural planes and horizontal is 60 ∘ ; and the shortest distance from the tunnel center to the weak structural plane is 10 m. The model was gradually loaded until ℎ and V reached the initial stress level; that is, ℎ = 32 MPa and V = 57.6 MPa ( ℎ and V were the initial stresses in the horizontal and vertical directions, resp.…”