Numerical investigation of the effect of holes on dynamic fracturing in multi‐flawed granite

Abstract

A numerical study is conducted using the improved continuum-based discrete element method (CDEM) to investigate the effect of holes on the dynamic fracturing of multi-flawed rocks. The specimen geometries contain a perpendicular crack-like flaw, a hole-like flaw, and an inclined crack-like flaw. A fracture model is implemented into the improved CDEM that combines the nonlinear pressure-dependent shear strength and tensile strength of rocks. The digital image correlation method combined with ultra-high-speed photography is applied in a split Hopkinson pressure bar system to verify the accuracy of the proposed model. The experimental results show that the improved CDEM accurately reproduces dynamic crack behavior in rocks. The simulation results show that hole-like flaws significantly affect crack behavior compared with the two investigated crack-like flaws. However, this effect gradually weakens with increasing loading stresses. This study provides important insight into the dynamic fracturing of multi-flawed rocks.

Experiments and numerical simulations on dynamic crack behavior at the interface of layered brittle material

“…49 The CDEM domain can be used to simulate the evolution of block elements from a continuous to a discontinuous field by constructing contact interfaces between adjacent blocks. 50 As shown in Figure 8, the discrete domain is created along the anticipated crack path, and the remaining part is set as the continuous domain. This greatly reduces the required computation time because the discretization of the entire numerical model is avoided.…”

“…The computational domain can be discretized into finite elements, which can be partially continuous, that is, CDEM domains 49 . The CDEM domain can be used to simulate the evolution of block elements from a continuous to a discontinuous field by constructing contact interfaces between adjacent blocks 50 . As shown in Figure 8, the discrete domain is created along the anticipated crack path, and the remaining part is set as the continuous domain.…”

Measuring J‐R curve under dynamic loading conditions using digital image correlation

“…In recent decades, the Hopkinson bar tests have observed vast development in pressure, tension, torsion, shear, bending, and combined loading conditions. 6,7 Gama et al 8 provide general guidelines for the configurations and specimen setup of the Hopkinson bars. Their recommendations alleviate common issues such as the wave dispersion in the impact tests and enhance the accuracy of the dynamic stress-strain curves based on the classical 1D wave theory.…”

The influence of infilling material strength on mechanical properties and failure mechanism of fractured sandstone

“…3 Since then, scholars have systematically studied the influence of various factors, such as the number, size, and dip angle of prefabricated cracks, on the mechanical properties of fractured rock and have investigated the law of crack growth, energy evolution characteristics, and failure mechanism. [4][5][6][7][8][9][10] However, in actual engineering projects, rock masses are subjected to multidirectional stress, particularly at great depths, and the resulting environmental stress cannot be ignored. Some scholars have studied the influence of the lateral pressure coefficient and confining pressure on the mechanical behavior and crack growth mode of fractured rock and further revealed its failure mechanism.…”

“…Brown et al conducted uniaxial compression tests on brittle rock specimens with a single crack and preliminarily explained the crack initiation and propagation mechanism of rocks based on the Griffith fracture mechanics theory 3 . Since then, scholars have systematically studied the influence of various factors, such as the number, size, and dip angle of prefabricated cracks, on the mechanical properties of fractured rock and have investigated the law of crack growth, energy evolution characteristics, and failure mechanism 4–10 . However, in actual engineering projects, rock masses are subjected to multidirectional stress, particularly at great depths, and the resulting environmental stress cannot be ignored.…”