THERMOMECHANICAL PROPERTIES OF DEEP ARGILLACEOUS FORMATIONS

A difficulty in the interpretation of mechanical and thermo-mechanical tests on specimens drawn from large argillaceous formations is the st rong inhomogeneity of void ratio, clay minerals and carbonates content . In this paper a relationship is developed to link strength and the m aximum preconsolidation stress to the initial void ratio and carbonate content. Compressibility is also correlated to carbonates. Thermal st rains in drained and undrained conditions for a Spanish, a Belgian and an Italian natural clay are compared. In the elastic state strains ar e comparable, while in the plastic range thermal strains are highest f or the Belgian clay, lower in the Spanish cemented clay and lowest in the Italian clay, very stiff and cemented.