Abstract

In the case of a circular shaft, it is expected that asymmetric loads should apply on the surface rather than symmetric loads due to geographical factors and the non-homogeneity of the jointed rock masses. In this study, discontinuous numerical analysis was carried in order to analyze the characteristics of asymmetric load distribution on the wall of the circular shaft due to anisotropy caused by heterogeneity of rock masses affected by the discontinuities like as a joint. And it was also analyzed that the effect of the mechanical properties varied with the rock mass rating and horizontal stress with depth had influence in the asymmetric load on the wall of the shaft. In the case of considering the effect of the joint as variable, asymmetric load ratio (Rp), which was defined as the ratio of the load subtracted minimum from maximum to minimum, was below 25% in the hard rock. As regarding the variation of the rock mass rating with depth as variable, the value of Rp was below than 25% in the hard rock, and the value between 30% and 40% in the soft rock. On the other hand, the Rp of fractures rock was between 45～50% which value was much higher than that in better rock mass rating.