Progressive failure of jointed rocks

Abstract

As jointed rocks consist of joints embedded within blocks of 'intact' rock, the behaviour of such rocks will depend on the behaviours of the joints and the intact rock blocks. In the jointed rocks, there are two levels of heterogeneity: (1) the differences in properties between the rock blocks and the joints and (2) the heterogeneity within the rock blocks due to the difference in the degree of weathering and the randomly distributed flaws. Furthermore, as water normally exists in the jointed rocks, the pressure and flow of the water will also have significant effect on these parameters. In this paper, a finite element model, based on the Biot's theory, is developed to predict the behaviour of jointed rocks by taking into account the above factors. The joints are modeled by elements with low moduli and strengths whereas the heterogeneity of the rock properties of the 'intact' rock are taken into account by assuming that they obey the Weibull's distribution. Studies are conducted to identify the effects of the water and joint pattern on the behaviour of jointed rocks. © 2004 Elsevier Ltd.