Statistical joint modeling and removability analysis of rock blocks around a rail-road tunnel

Abstract

Geometrical modeling of rock joints in 3D space determines the geometrical parameters of joints such as orientation, frequency, size, shape and location. Joint size and volumetric frequency among the parameters are very difficult to obtain because a complete joint plane within rock mass cannot be observed directly. In this study, a recent technique developed by the author was used to estimate the joint size and volumetric frequency. The developed technique uses the least square method to estimate the joint diameter distribution, whose by-product is the volumetric frequency. This technique was applied to a cut slope close to a rail-road tunnel under design and the removability of rock blocks formed by circular joints simulated by statistical estimation was analysed. The volume, height, perimetric length and occurrence probabilities of rock blocks around a tunnel were calculated. The block analysis result was compared with that of a commercial program, UDEC (Universal Distinct Element Code).