Influence of water content on mechanical behavior of basalt in Baihetan Hydropower Station, China

Water content is a critical factor affecting rock strength in numerous geotechnical engineering applications. This study experimentally investigates the influence of water content on the mechanical behavior of basalt in the Baihetan Hydropower Station. Uniaxial compression tests were performed on basalt specimens at five moisture content levels. The strength evolution of shale and sandstone specimens with different water content levels were also analyzed through an extensive literature review. The results show that an increase in water content can exacerbate the initial damage to the basalt specimens, increasing the nonlinearity in the initial deformation stage of the stress-strain curve. As the water content increases, both uniaxial compressive strength and Young's modulus gradually decrease, but Poisson's ratio remains almost constant. Splitting failure is the dominant mode for all tested specimens. Because of the differences in pore structures and mineral compositions, the mechanism of water-weakening on the compressive strength of shale, sandstone, and basalt is different. The negative exponential function provides a good representation of the compressive strength versus water content of shale and sandstone, but unsuitable for describing that of basalt.