Post-peak behavior of rock is significant to the stability of surface and underground rock excavations and the performance of drilling and excavation operations. Mechanical properties and damage characteristics of rocks are subjected to the measurement scale. The effect of size on sandstone's post-peak behavior and failure characteristics are investigated during monotonic uniaxial compressive loading. A series of tests were undertaken on sandstone samples with an aspect ratio of 2.5 and diameters of 19mm, 30mm, 42mm, and 63mm. The lateral strain-controlled loading method was adopted to capture the post-peak stress-strain characteristics. The three-dimensional digital image correlation (3D DIC) technique is utilized to investigate field strain patterns and local damage. The brittleness index was found to increase with an increase in diameter, indicating that the rock sample was damaged in a more brittle regime with a larger size. 3D DIC results demonstrated that in the pre-peak regime, the specimen deforms uniformly. In the pos-peak regime, however, the specimen shows localized behavior. This behavior is different for samples having different diameters. The overall post-peak was a combination of class I and class II behavior.
KEYWORDS
Sandstone; Post-peak; Brittleness; Digital Image Correlation, Damage
