SIMPLISTIC GEOTECHNICAL ANALYSIS OF NUCLEAR WASTE REPOSITORY

Abstract

The deep geological sites provide a natural isolation system that is stable over hundreds of thousands of years to contain long-lived radioactive waste. High-level radioactive waste is disposed in host rocks that are crystalline (granitic, gneiss) or argillaceous (clays) or salty or tuff. The rock masses are largely DIANE (discontinuous, inhomogeneous, anisotropic and non-elastic) in nature hence numerical modeling becomes inevitable for the design and performance assessments of rock engineering projects. Knowledge of the coupled thermo-mechanical (T-M) processes about evolutions of geometrical structures and constitutive behavior of the fractured rock masses under combined loading conditions and temperature gradients becomes essential for the reliable solutions of many rock-engineering problems, especially when impacts on environment are required to be understood. The details of the extensive numerical study on the thermo-mechanical effect on the rock mass subjected to in-situ stresses and thermal loading were available from literature. The stress and displacement response with time due to thermal loading were available. The objective of the present study has been to numerically analyze the mechanical behavior of the rock mass due to temperature increase and conduct the parametric studies using Universal Distinct Element Code. To fulfill this objective a case study was selected. The model used for this study was. taken from verification problem of UDEC 3.1. The present study included prediction of the mechanical behavior of the rock mass by distinct element modeling, study the influence of various parameters i.e. drift scale, repository scale, thermal loading, joint property and the prediction of the mechanical behavior of the repository in Indian condition.