Joint Network Modeling And Some Scale Effects In Rock Masses

The presence of discontinuities strongly affects the mechanical and hydraulic behavior of rock masses. Joint geometry networks play a vital role in civil, mining, and petroleum engineering projects associated with jointed rock. The need for a realistic representation of joint geometry in rock masses has been recognized. The first part of the paper shows how to build three-dimensional stochastic joint network schemes and also shows how to perform validation studies for these schemes using joint data from the Stripa mine, Sweden. Due to the existence of complex joint patterns, mechanical behavior of jointed rock masses usually exhibit scale effects and an-isotropic properties. A correct understanding of the mechanical properties (strength and deformability) of jointed rock masses is important for designing and performance estimation of structures build in and on rock masses. Beyond a certain volume, the mass proper-ties of the rock may remain essentially constant with respect to the effect of joints. This minimum volume may be used as the element size to represent the equivalent properties of a statistically homogeneous rock mass volume which contains a significant number of joints. This volume may be termed as a "Representative Elementary Volume" (REV) and may be of great importance for engineering purposes. Investigations are underway at both the 2D and 3D levels to look into the possibility of establishing relationships between REV mechanical properties and joint geometry parameters. Recently developed joint geometry modeling schemes are linked with existing distinct element codes (both 2D and 3D) to create a stochastic/deterministic stress analysis approach in achieving the goal. Results obtained so far in this direction are presented in the second part of the paper.