Studies on the Deformation and Macro-Micro-Damage Characteristics of Water-Bearing Sandstone under Cyclic Loading and Unloading Tests.

The study of the deformation characteristics and damage evolution law of the underground water-bearing rock mass under reciprocating loads such as mine earthquake and mechanical vibration is a very crucial aspect of underground engineering. In this pursuit, the present study was envisaged to assess the deformation characteristics and damage evolution law of sandstone with different water contents under various cycles. Specifically, the uniaxial and cyclic loading and unloading tests, X-ray diffraction (XRD), and scanning electron microscope (SEM) tests of the sandstone under dry, unsaturated, and saturated conditions were carried out under laboratory conditions.

Dynamic tensile properties, deformation, and failure testing of impact-loaded coal samples with various water content.

Disc coal samples with different water content were tested using the split Hopkinson press bar test system. Their dynamic tensile failure process was monitored via an ultra-high-speed digital image correlation system. The deformation trend and failure characteristics as a function of the water content were analyzed, and the water content effect on dynamic mechanical properties was investigated.