Effect of heterogeneity of brittle rock on micromechanical extensile behavior during compression loading

Abstract

[1] A grain-based Universal Distinct Element Code model was developed to generate a deformable polygonal grain-like structure to simulate the microstructure of brittle rock. It takes into account grain-scale heterogeneity including microgeometric heterogeneity, grain-scale elastic heterogeneity, and microcontact heterogeneity. The microgeometric heterogeneity can be used to match the grain size distribution of the rock. The discrete element approach is able to simulate the microheterogeneity caused by elastic variation and contact stiffness anisotropy. The modeling approach was evaluated using Lac du Bonnet granite and Ä spö Diorite. The microheterogeneity played an important role in controlling both the micromechanical behavior and the macroscopic response when subjected to uniaxial compression loading. The crack-initiation stress was found to be controlled primarily by the microscale geometric heterogeneity, while the microcontact heterogeneity controlled the strength characteristics. The effect of heterogeneity on the distribution and evolution of tensile stresses and associated extension cracks was also examined.Citation: Lan, H., C. D. Martin, and B. Hu (2010), Effect of heterogeneity of brittle rock on micromechanical extensile behavior during compression loading,

A grain based modeling study of mineralogical factors affecting strength, elastic behavior and micro fracture development during compression tests in granites

“…Therefore, four different mineral types are explicitly modeled in this study. A GBM modeling approach also exists for UDEC [44] but in this approach the grains are unbreakable such as in PFC2D clumped particle models.…”

Geothermal-Related Thermo-Elastic Fracture Analysis by Numerical Manifold Method

“…The last term in Equation (19) is the contact heat transfer terms which have to satisfy the heat flux continuity condition given in Equation (13) and the temperature condition given in Equation (16). By substituting Equation (14) and (18) into Equation (19), the discretized governing equation for transient heat conduction with contact heat transfer among cemented grains can be established:…”

“…Since the continuous numerical methods run into difficulties when simulating thermal fracturing of granular materials, the discontinuous numerical methods are also widely adopted to deal with such problems [13][14][15][16]. One widely used discontinuous numerical method for thermal fracturing is the particle flow code (PFC), in which the micrograins are represented by circular or spherical elements [13].…”

Nanomechanical Characterization of Brittle Rocks

“…Figure 1 shows some examples of microdiscontinuities in a granite's sample. More generally, the discontinuous nature and heterogeneity of rocks at the grain scale are well described in Blair andCook (1998) andin Lan et al (2010).Depending on their distribution, nature and statistically prevailing orientation more than grains iso-orientation, the defects affect the rock's mechanical behavior at a varying extent.The microdiscontinuities are surfaces along which the failure processes of the rock samples under critical state of stresses originate (Tapponnier and Brace 1976;Kranz 1979;Wong 1982). Consequently, to properly understand the mechanisms leading to the rock's macroscopic failure, analyses should be performed even at the micro and nanoscale (discontinuities scale), where the failure begins.…”