Experimental investigation on dilatancy behavior of marble with pre-existing fissures under different confining pressures

Based on the obtained volumetric-axial strain curves of marble with pre-existing fissures under different confining pressures,the effect of confining pressures on dilatancy behavior of marble with pre-existing fissures is analyzed.The results show that the crack damage thresholds of intact and pre-cracked marble all increase linearly with the confining pressures,and that the sensibility of the crack damage thresholds to the confining pressures is lower than that to the peak strength.Under the same confining pressure,the medium marble with smaller grain sizes has higher crack damage threshold.The long-term internal friction angles of intact and pre-cracked marble are lower distinctly than the short-term,but the reducing extent of long-term cohesion is closely related to fissure geometry.The higher the peak strength of intact or pre-cracked marble,the larger the corresponding crack damage thresholds.The peak strength of intact and pre-cracked marble has a good linear relation with the crack damage thresholds.The conclusions are significant for the choice of mechanical parameters of rock mass with jointed fissures when carrying out engineering design and numerical simulation.