ABSTRACT
The conditions under which soft rocks are degraded due to physical or chemical weathering had been well established (Hawkins et al. 1988). However, very few efforts have been made so far towards constitutive modelling of degradable geomaterials e.g. Feda (2002), Castellanza & Nova (2004) and Pinyol et al. (2007). The motivation behind this study was from some shear tests conducted on conventional nondegradable geomaterials (Toyoura silica sand) which showed no change in stress-strain response in dry and saturated test conditions. Such results are also verified by Fioravante & Capoferri (1997). The main objective of this research is to formulate the process of loss of strength and stiffness of degradable geomaterials for their better stress-strain response modeling, especially sedimentary soft rocks due to their rapid water-induced deterioration. As shown in Figure 2, a piece of mudstone rapidly disintegrates and transforms from rock to soil only after a few minutes of submergence in water.
