Mechanical behaviors and failure mechanism of flawed sandstone containing infillings under freeze-thaw cycles and uniaxial compression

Abstract

The flawed rock masses with joints, fissures, and other defects in cold regions engineering are affected by freeze–thaw (F-T) cycles. Substantial efforts have been focused on the mechanical properties and failure characteristics of flawed rock masses under F-T cycles. However, only a few laboratory tests have considered the effect of fillers in the rock flaws under F-T cycles. In the present work, F-T cycling and uniaxial compression tests are conducted on intact sandstone, flawed sandstone containing infillings, and flawed sandstone without infillings to further investigate the effects of fillers and the number of F-T cycles on the mechanical behaviors and failure mechanism of flawed sandstone containing infillings. The experimental results indicate that filling the flaws can effectively inhibit mass loss and pore growth of flawed sandstone specimens in the early stages of F-T cycles. Fillers can effectively reduce the stress concentration at the flaws and improve the strength of flawed specimens. In the early stages of F-T cycles, crack propagation caused by uneven stress and deformation at the flaws leads to the failure of the specimen. As the number of F-T cycles increases, the peak stresses of the specimens are gradually decreased, and the reduction of the cementation strength between rock particles causes particle loss and cracking failure in the specimens. The failure characteristics of flawed specimens containing infillings are significantly different from those of other two types of specimens. Based on the test phenomena, a deterioration failure mode for F-T failure of flawed specimens containing infillings is proposed.