Three-Dimensional Joint/Interface Element for Rough Undulating Major Discontinuities in Rock Masses

Abstract

Major civil engineering structures are being constructed now a days in complex geological environment with faults, shear zones, and other major discontinuities. These major discontinuities can cause a variety of problems in both surface and underground constructions. Unfavorably dipping major discontinuities may create unstable conditions in underground openings and contribute to the deformations of a rock mass under external static loading. Hence, rock–structure interaction analysis should simulate arbitrarily oriented rough and undulating major discontinuities within the rock mass, as well as the undulating interface along the structure and the rock mass such as dam foundations and underground excavations intersected by fault/shear zones. Realistic simulation of the mechanical behavior of rock joints is a prerequisite for successful numerical modeling of discontinuous rocks. When joint modeling is designed to include different degrees of joint roughness, dilation, and aperture, then realistic response depends upon the appropriate constitutive models and the way these parameters interact with stress change. Due to low values of the normal and tangential module, a unique characteristic of a rock discontinuity is that dilation may occur as soon as relative slip takes place and this may significantly alter the stress distribution, particularly around an underground excavation. In view of these practical requirements, a generalized formulation of a three-dimensional joint/interface element has been proposed here to account for dilatancy, roughness, and undulating surface of discontinuities.