Spatial Propagation Effects of 3D Cracks on Mechanical Properties of Geomaterials Under Uniaxial Compression by 3D Reconstruction

Understanding the 3D spatial cracking behavior plays significant role in evaluating the mechanical properties of rocks. This work studied the spatial propagations of 3D cracks and its effects on the mechanical properties during the failure process of sandstone under uniaxial compression using X-ray CT imaging and 3D reconstruction techniques. Results show that five cracking stages can be identified including the initial flaw compaction stage, linear elastic deformation stage, microcrack propagation and coalescence to macrocrack formation stage, stable propagation stage of macrocracks and the sample failure stage. As cracking direction increases from 0° to 90°, peak stress decreases, microcrack initiation stress increases for sample S1 and decreases for samples S2–S3, which is opposite to macrocrack initiation stress of cracks. However, these variations of microcrack initiation stress, macrocrack initiation stress and peak stress are opposite as cracking direction increases from 180° to 270°. The proposed relation between the stress and normalized damage volume is effective to evaluate the stress during the failure process of sandstone.