A compression damage constitutive model of jointed rock mass based on deformation components

In order to study the mechanical response of the jointed rock mass under compression load, the deformation of jointed rock mass under compression load was regarded as the summation of rock block deformation and joint face deformation according to the viewpoint of rock structure mechanics. And the deformation laws of rock block and joint face under compression load were described with the elastic damage deformation component based on the statistical damage model and the joint closure and slippage deformation component, respectively. Then, the corresponding compression damage constitutive model of the jointed rock mass was established. The effect laws of such joint parameters as elastic modulus, maximum closure strain and shear stiffness on the calculation results were discussed with this model. Finally, the stress-strain curve of the rock mass with one single continuous joint under compression load was calculated with this model. The results show that the effect of the joint shear stiffness on the calculation results is the largest to the rock mass which can possibly slip along the joint face. The climax strength of jointed rock mass in this calculation example is only 51.5% of intact rock, which perfectly reflects the deterioration effect of the joint on rock mass strength. Meanwhile, the parabola change law of rock mass strength with the joint dip angle is obtained with this model, which shows that the rock mass strength is minimum when the joint dip angle is between 50°-60°. This conclusion fits very well with the current experimental and theoretical results, which indicates the rationality of this model.