Dynamic compressive mechanical properties and fracture mechanism of conglomerate

Abstract

Conglomerate rock’s complex and heterogeneous microstructure significantly affects its mechanical properties, especially under dynamic loading. However, research on their dynamic behavior and fracture mechanisms is limited. Through uniaxial compression tests and split Hopkinson pressure bar (SHPB) impact tests, the dynamic compressive mechanical properties and fracture mechanisms of conglomerate rock were studied. Nanoindentation and high-resolution X-ray computed tomography were employed to analyze the micro-mechanical behavior and internal structure of the conglomerate rock. Results indicate significant differences in mechanical properties between different gravel particles and cementing materials, with initial fractures primarily distributed at the gravel-cement interfaces. The dynamic mechanical properties of conglomerate rocks exhibit a clear strain rate dependency. Based on the stress – strain curves and failure characteristics, the dynamic compressive mechanical behavior can be categorized into two types using a critical strain rate. The dynamic compressive strength, peak strain, and toughness of conglomerate rock increased with the strain rate, with the strength at 54 s⁻¹ being 2.6 times that at 6 s⁻¹. The dynamic compressive fracture mechanism of conglomerate rock is related to the strain rate and microstructure; at low strain rates, gravel distribution is the key factor, whereas at high strain rates, gravel content becomes critical.

Keywords

conglomerate / compressive response / realistic micro-heterogeneity / fracture mechanism / strain rate dependency

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