A statistical model considering the effect of confining pressure on the size effect of rock strength

Based on the characteristics of stochastic distribution of the physical and mechanical properties of rock micro-unit,the Weibull distribution is chosen as the probability distribution model. Using the MohrCoulomb criterion to represent the micro-unit strength,a statistical model considering the effect of confining pressure on the size effect of rock strength is established. By comparing with previouse models,this model can characterize the effect of confining pressure on the size effect of rock strength. The effect of heterogeneity and confining pressure is also examined. The results indicate that the heterogeneity of rock is the root cause of discreteness and size effect. More homogeneous rocks may lower the discreteness of strength and have less prominent size effect. The confining pressure has an effect on the size sensitivity. Larger confining pressure makes the rock strength increase,and reduces the proportion of strength induced by the size effect and leads to less prominent size effect.