Statistical model for structure of jointed rock mass

It is well known that the engineering behaviour of rock mass is strongly affected by its structure. Therefore a suitable method and model to describe the structure of rock mass are the basis of rock mechanics. A number of scientists have devoted themselves to the research of rock mass structure and its mechanical effects during recent decades. Priest & Hudson (1976, 1981) and Hudson & Priest (1983) advanced geometrical probability methods to measure and analyse the frequency, spacings and trace lengths of discontinuities in homogeneous rock mass. Kulatilake & Wu (1984) introduced their statistical window method to measure and evaluate the average trace length of cracks. Oda (1986) developed a fabric tensor method to describe the rock mass structure applied to coupled stress and fluid flow analysis. However, it is still difficult to build a basic structural model for rock mass so as to develop mechanics theory. There should be a geometric model comparable with that currently used in practice that can provide some structural parameters and can be used to derive a constitutive model, strength theory and hydro-conductivity model. This paper attempts to set up a statistical model that may make up the basis of rock mechanics.