The International Conference on Discrete Fracture Network
Engineering, October 19 - 22, 2014, Vancouver, Canada
The Influence of Joint Termination on the Mechanical
Properties of Rock Masses - A SRM Approach
K. Esmaieli, V. Varjao, S. Aziznejad
Lassonde Institute of Mining, University of Toronto, Canada
Abstract
The mechanical properties of a rock mass can be influenced by the intact rock properties
as well as the mechanical and geometrical properties of joints. Usually only the primary
geometrical characteristics of joints such as joint shape, planarity, size, spacing,
orientation, and aperture are used to describe joints. Joint termination is a secondary joint
characteristic that divides joints into two main categories: joints that terminate at the
intact rock and joints that terminate at the intersection with other joints. Although the
effects of primary characteristics of joints such as orientation, continuity and frequency
of joints, on the rock mass strength have been widely studied, the influence of joint
termination pattern on the rock mass mechanical properties has not been completely
understood.
This paper aims to present the results of a series of numerical modeling that shows the
influence of joint termination on the mechanical properties of rock masses. To analyze
the effect of joint termination, two discrete fracture network (DFN) models were
developed. These conceptual DFN models could represent moderately jointed rock
masses. Each model consists of two inclined joint sets. Input parameters such as: dip, dip
direction, size distribution and volumetric intensity (P32) of the joint sets for the two DFN
models were kept the same, except the joint termination percentage where a zero
termination and a 100% termination were assigned to the DFN models, respectively. A
DFN model with zero termination implies that all joints within the sample terminate at
the intersection with other joints. Five realizations were generated for each model. In all
ten stochastic DFN models were generated. These models were embedded into a 3D
bonded particle model, simulates the mechanical properties of an intact rock. This
allowed generation of ten Synthetic Rock Mass (SRM) samples. The SRM samples were
uniaxially loaded until the samples failed. The ultimate compressive strength as well as
the elastic modulus of these samples measured during the tests. Comparison of the results
of the SRM samples with zero termination and 100% termination indicates that on
average the samples with zero termination have slightly higher uniaxial compressive
strength and elastic modulus.