Folds, fractures and faults in rock masses Reference materials in rock mechanics: the rock mass, the intact rock, the discontinuities or rock joints. Geometrical analysis, nomenclature and classification of folds. The folding process for a theoretical single rock layer. Stress state and deformation within a folded rock stratum. Mechanical processes originating a folded multi-layered rock mass. Concentric and similar folds. Geometrical features, classification and nomenclature of various types of faults. Normal faults, reverse faults, thrust faults and strike-slip faults. Relationships between folds, fractures and faults. (15 h)
Stress and deformation in rock masses Compressive, tensile and shear stresses in rock materials. The mechanical approach based on the analysis of the three main stresses σ1, σ2 and σ3. The calculation of the stress state acting on a generic plane. The graphical method of the Mohr circle to determine the stress state acting on the critical failure plane of a rock sample. Characteristic fracture modes for the intact rock and relationships between the fracture geometry and the main stresses. Rock discontinuities in various geological context and the influence of the reference volume: small-, medium- and large-sized rock structures. (15 h)
Characterization of the “intact rock” material Typical laboratory tests carried out on rock samples. The conventional uniaxial compressive test: characteristic experimental diagrams, stress and deformation analysis. The tensile test and the Brazilian test. The indirect estimation of the compressive strength for different rock types by using the Schmidt Hammer, type L and N. The Point Load Test (PLT) on cylindrical samples and on irregular lump specimens to determine the characteristic compressive and tensile strength. (15 h)
The rock mass classification Various technical classifications adopted to describe the rock mass. The reference rock mass classification proposed by BIENIAWSKI (1973) and further modifications (1989). Characteristic parameters and calculation of the index RMR (Rock Mass Rating). Basic RMR, dry RMR and adjusted RMR. The rock mass classification formulated by ROMANA (1985) to determine the index SMR (Slope Mass Rating) specifically related to the rock slope stability. The failure criterion and the rock mass classification based on the method suggested by HOEK & BROWN (1980, 1988 and 1997). Practical application of the HOEK & BROWN approach to classify real rock masses. (15 h)