Uniaxial Compression Testing of Sandstone under Microscope: Damage Characteristics and Failure Mechanisms

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Uniaxial Compression Testing of Sandstone under Microscope: Damage Characteristics and Failure Mechanisms

Hu, Huarui / Xia, Binwei / Chen, Cancan / Peng, Jiajun / Cao, Shirong / Li, Yangyang

A compression module system placed under a microscope was utilized to conduct uniaxial compression testing of sandstone samples. The test system can acquire the image of crack propagation on the specimen surface in real time. The focus of this study was to analyze how the motion of sandstone composition particles affect the failure mechanism of the samples under minimal loading rates. The results indicate that the load displacement curves align with the macroscopic failure laws under different loading rates. Furthermore, the lower the loading rate, the greater the deformation and crushing degree of sandstone during failure. The failure mode becomes more complex and gradually transitions from tension failure to shear-tension failure. The crack evolution of sandstone was caused by the uncoordinated movement of its components, and the weak structure induces cracks under the action of external load. Microcracks are initially generated at the interface between mineral particles and the sandstone matrix and propagate along the boundary between mineral and matrix. The interaction between component particles in sandstone leads to the connection break between particles which forms microcracks, and results in local deformation of the sample. The aggregation of multiple cracks leads to the instability and failure of sandstone.