Micromechanical Modelling of the Complete Stress-Strain Relationship for Crack Weakened Rock Subjected to Compressive Loading

A micromechanics-based model, able to quantify the effect of various parameters on the complete stress-strain relationship, is described. The closed-form explicit expression for the complete stress-strain relationship of a rock material containing an echelon cracks arrangement subjected to compressive loading is obtained. The complete stress-strain relationship including the stages of linear elasticity, non-linear hardening and strain softening is established. The results show that the complete stress-strain relationship and the strength of rock with echelon cracks depend on the crack interface friction coefficient, the sliding crack spacing, the perpendicular distance between the two adjacent rows, the fracture toughness of rock material and orientation of the cracks. The present model is used to evaluate the complete stress-strain relationship and strength for crack-weakened rock at the underground cavern complex of the Ertan Hydroelectric Project. The predicted strength is in agreement with that obtained by the Hoek-Brown criterion. The numerical results obtained with the complete stress-strain relationship seem to be in good agreement with the measured values.