This report summarizes the work contributed to Phase 2 of Task B of the international DECOVALEX-THMC project, which took place during the period of March 2004 to May 2006. The Phase 2 work incorporated the use of a wide range of numerical models to simulate the failure of a number of intact rock core samples, from the APSE tunnel at Äspö HRL, as tested in uniaxial compression and other loading conditions with the intention of establishing the common and code-specific features of the models. The core samples of the Äspö diorite were treated with different initial mechanical and chemical conditions as dry samples, saturated with distilled water, formation water and saline water, with different durations of submersion, respectively, in order to observe the mechanical effects of saturation by different chemical fluids on the mechanical properties of the intact core samples. .
In order to understand the physical-chemical processes involved and the damage mechanisms of the cores, various numerical modelling approaches were applied to simulate the core testing, including FEM, DEM, BEM and EPCA (Elasto-Plastic Cellular Automata) methods. The application of such widely different numerical approaches provides a very useful platform for deeper understanding of not only the main features of numerical methods but also their characteristics for representation of the damage mechanisms.