Abstract: To investigate the effect of fracture water pressure and confining pressure on the  mechanical properties of fractured marble rock, we produced marble rock specimens which fit with the confining pressure and osmotic pressure of testing machine system(MTS815 Flex Test GT)  via special techniques and geological process simulation. We then carried out water pressure-stress field coupling triaxial tests under different water pressures and different confining pressures. Results showed that the strength and deformation properties of the rock decreased with the increase of water pressure, and increased with the rise of confining pressure. During water pressure changed  from 0 to 4 MPa, the strength parameter f decreased by 20%, the cohesion C decreased remarkably, and the  deformation modulus E₀ and E₅₀ decreased 7.7% and 5.9% respectively. During confining pressure changed from 5MPa to 30MPa, f decreased a little, C  increased more than 2 times, E₀ and E₅₀ increased 58% and 50% respectively. These conclusions reveal the marble rock's mechanical properties under different water pressures and different confining pressures, and offer important reference to solve practical engineering problems.

Key words: marble rock, fractured rock mass, fracture water pressure, water pressure-stress coupling