Mechanical and Volumetric Fracturing Behaviour of Three-Dimensional Printing Rock-like Samples Under Dynamic Loading

Abstract

Heterogeneous rock contains numerous pre-existing three-dimensional (3D) cracks, which control its mechanical and fracturing properties. Considerable effort has been devoted to studying the volumetric fracturing behaviour of rock under static loading conditions. Although rock masses are often subject to dynamic impacts such as earthquakes and blasting, the mechanical and volumetric fracturing behaviour of rock under dynamic loading is still poorly understood. In this paper, dynamic laboratory tests were performed on 3D-printed artificial rock samples with 3D embedded flaws created during three-dimensional printing (3DP), with the aim of studying the volumetric fracturing and mechanical properties of these samples under impact with high strain rate. The results show that the dynamic compressive strength and the tangent modulus decrease with an increasing number of flaws, but have very limited effects on the ratio of the fracture initiation stress of the first crack to the peak stress of the sample, the maximum axial strain of the sample and the volumetric fracturing behaviour of the sample. The tensile failure of a sample is caused by the continuous extension of wing cracks from the outer flaw tips. The mechanical and volumetric fracturing behaviour of samples with 3D embedded flaws are strain rate dependent. The tangential modulus and the ratio of the fracture initiation stress of the crack to the peak stress increase significantly when the loading type changes from static compression to dynamic compression. Under dynamic compression, wing cracks can continuously extend to the sample ends, whereas under static compression, wing cracks can intermittently extend only a limited distance. Moreover, the fracturing behaviour of 3D flaw differs from that of 2D flaws under dynamic loading. Under high strain rate loading, wing cracks generated at 3D flaw tips lead to splitting failure of the sample, while shear cracks formed at 2D flaw tips result predominant shear failure of the sample. The findings in this paper could facilitate a better understanding of rock failure subjected to dynamic loading conditions.

Compression‐induced crack initiation and growth in flawed rocks: A review

“…5,[194][195][196][197] Therefore, understanding the responses of flawed rocks to engineering disturbances, especially the dynamic strength and dynamic crack propagation characteristics, is essential to guarantee the reliability and safety of engineering projects during construction and operation periods. 5,198 Although rock masses are often subjected to dynamic disturbances, the mechanical and volumetric fracturing behavior of rock under dynamic loading is still poorly understood. This is mainly because the rock dynamics theories are still at its infancy in spite of extensive previous efforts devoted to rock dynamics.…”

Energy Dissipation and Particle Size Distribution of Granite under Different Incident Energies in SHPB Compression Tests

“…Rock structures are frequently subjected to dynamic loads from rock drilling, rock blasting, rock bursts, and seismic events or earthquakes [1][2][3][4]. Under dynamic loads, rock damage or fracture may occur and energy consumption happens [5][6][7]. Accordingly, it is of importance to investigate energy dissipation in the process of rock fracture [8][9][10][11][12][13][14][15].…”

An Experimental and Numerical Investigation on the Initiation and Interaction of Double Cracks in Rocks under Hydromechanical Coupling

“…erefore, the spatial distribution form of double cracks greatly affects the distribution of stress fields around cracks, and the interactive weakening or enhancement effect occurs due to the stress superposition, which has a significant influence on crack initiation and growth characteristics. Moreover, Wong et al, Lu et al, Fu et al, Zhu et al, and Zhou et al have confirmed that the fracture behavior of 3D cracks is significantly different from that of 2D cracks [40][41][42][43][44], which is mainly reflected in the fact that the spatial propagation mode of 3D cracks is more complex, and there are intrinsic limits on 3D propagation of wing cracks, resulting in great change in rock failure mode. In our study, the contribution of mode II and mode III fracture to the 3D crack growth is investigated, and the influence of crack distribution and interaction characteristics is clarified in detail.…”