Unconfined and Triaxial Compression Tests on Hollowed Cylindrical Sandstones to Explore the Infilling Effects on the Deformation and Mechanical Behaviors

Abstract

In practical engineering, the mechanical properties of the surrounding rock often reflect the bearing capacity of the support. To investigate the relations between the surrounding rock and the support, solid specimens, hollowed cylinders, and hollowed cylinders filled with two kinds of cement mortars are tested under unconfined and conventional triaxial compressions. The effects of the infilling on the stress-strain curves, deformation features, mechanical properties, and failure patterns are schematically investigated. The results show that under the triaxial compression condition, each infilled specimen exhibits obvious residual carrying capacity though a slight stress drop occurs after the peak stress. The cement mortar exerts a positive effect on the carrying capacity of the rock, and the infilling having a higher strength and stiffness contributes to a more pronounced enhancement of the overall strength of the specimens. Under the triaxial compression condition, merely a dominated shear fracture can be seen on the surfaces, and with relatively high confining pressure (σ3 = 20 and 30 MPa), both the rock and cement mortar were cut into two parts by the dominated shear fracture. The laboratory tests in this study provide a simple and feasible way of investigating the interaction of the support system with the surrounding rock.

Experimental Study on Energy Release Mechanism and Crack Propagation Evolution of Sandstone under True Triaxial Loading

“…Consequently, scholars, including Cai, have extensively researched the mechanical properties of deep rock masses based on triaxial compression tests [3]. Liu et al explored how fillers impact the deformation characteristics, mechanical properties, and failure modes of rock masses [4]. Tang et al [5] assessed how the loading rate affects the peak strength and post-failure resilience of rock masses under confining pressure, providing insights into the long-term deformation and stability of underground structures.…”