Three-Dimensional Combined Finite-Discrete Element Modeling of Shear Fracture Process in Direct Shearing of Rough Concrete–Rock Joints

Abstract

A three-dimensional combined finite-discrete element element method (FDEM), parallelized by a general-purpose graphic-processing-unit (GPGPU), was applied to identify the fracture process of rough concrete–rock joints under direct shearing. The development process of shear resistance under the complex interaction between the rough concrete–rock joint surfaces, i.e., asperity dilatation, sliding, and degradation, was numerically simulated in terms of various asperity roughness under constant normal confinement. It was found that joint roughness significantly affects the development of overall joint shear resistance. The main mechanism for the joint shear resistance was identified as asperity sliding in the case of smoother joint roughness and asperity degradation in the case of rougher joint asperity. Moreover, it was established that the bulk internal friction angle increased with asperity angle increments in the Mohr–Coulomb criterion, and these results follow Patton’s theoretical model. Finally, the friction coefficient in FDEM appears to be an important parameter for simulating the direct shear test because the friction coefficient affects the bulk shear strength as well as the bulk internal friction angle. In addition, the friction coefficient of the rock–concrete joints contributes to the variation of the internal friction angle at the smooth joint than the rough joint.

Dynamic splitting tensile behavior of rock–concrete bimaterial disc with multiple material types under different interface inclination angle

“…To better distinguish the phase characteristics of the two types of damage, the Mohr-Coulomb damage criterion for shear damage applicable to brittle materials is (Equation 19). 13,[59][60][61] The relationship between the normal stress and shear stress at the origin of the interface at the same angle is plotted in Figure 12B.…”

“…To better distinguish the phase characteristics of the two types of damage, the Mohr–Coulomb damage criterion for shear damage applicable to brittle materials is introduced (Equation 19). 13,59–61 The relationship between the normal stress and shear stress at the origin of the interface at the same angle is plotted in Figure 12B. where τ P is the shear stress at the interface; c is the cohesive force between the concrete–rock contact interface; σ n is the normal stress at the interface; φ is the angle of internal friction at the interface.…”

“…The interface damage mechanism under shearing action identifies as sliding failure in the case of the relatively smooth interface and asperity degradation in the case of the rough interface. 13 And the stress and strain of the rock–concrete composite specimens with contact restraint are sensibly higher than those without contact restraint 11 . The adhesion properties of the interface, on the other hand, do not depend on the rock strength but are related to the physical properties of the constituent particles for the rock 19 …”

“…Extensive research has been conducted on rock–concrete structures, including basic mechanical properties, 2,3,11 durability, 9,12 and numerical simulation 13,14 of the assemblies. Based on the engineering structural properties of rock–concrete assemblies, the interfacial shear properties, interfacial roughness, fracture behavior, deformation behavior, and energy dissipation of the composite have been investigated by scholars from different perspectives 5,7,15–18 .…”

Fracture Mechanics—Theory, Modeling and Applications

“…Min et al [6] numerically studied fracture processes of rough concrete rock joints under direct shear loading conditions, using an implementation of the 3D combined finite-discrete element method that had been parallelized for GPGPU (general-purpose graphic-processing-unit) architecture. The authors first presented the results of a material property calibration exercise that was used as a basis for the rest of the analysis.…”