Hydro-mechanical coupling behavior and statistical damage constitutive model of deep marble with disturbance

To study the effect of excavation disturbance on hydro-mechanical coupling characteristics of deep marble, both artificially disturbed and intact marble samples were tested under different osmotic pressures. The stress-strain curve, characteristic stress, failure mode and strain energy were then compared between the disturbed and the intact samples under osmotic pressure. Finally, a statistical damage constitutive model was proposed to consider osmotic pressure and initial deformation based on assuming that the micro-element strength of marble obeys Weibull distribution. It is found that the disturbed sample has slightly lower peak stress and damage stress than the intact sample, but its resistance to hydraulic damage decreases significantly. In the initial stage of loading, the ratio of elastic strain energy of the intact sample is generally lower than that of the disturbed one. The characteristic points of the elastic strain energy ratio curve can be a good reference to determine the damage stress. This finding makes up for the deficiency of possible failure of the single definition of damage stress. The proposed statistical damage constitutive model can well reproduce the stress-strain responses under different osmotic pressure. At the same strain level, the rock damage is more significant if the osmotic pressure is higher. This study is of great significance to the development of deep rock mechanics theory and its application in engineering practice.