Experimental Study of the Strength of Rocks

Dilatancy, compaction, and failure mode in Solnhofen limestone

“…We also tlsed the saturation technique to determine the interconnected porosities in selected samples, which were found to be -1.5%, indicating that the limestone contains a large proportion of unconnected, vugular type of pores. We did not determine the average grain size, but it was reported to be -5 gm in previous studies [Robertson, 1955;Heard, 1960;Edmond and Paterson, 1972;Fredrich et al, 1990;Renner and Rumreel, 1996;Fisher and Paterson, 1989;Rutter, 1972].…”

“…In the cataclastic flow regime the pore space undergoes significant inelastic compaction while the rock strain hardens [Edmond and Paterson, 1972]. The marbles, even the ones with very low porosity like the Carrara marble, undergo the brittle to plastic transition at room temperature for confining pressures accessible in the laboratory [Robertson, 1955;Paterson, 1958;Heard, 1960;Rutter, 1974]. This is probably due to the fact that calcite requires relatively low shear stresses to initiate mechanical twinning and dislocation slip even at room temperature [Turner et al, 1954;Griggs et al, 1960].…”

“…Although many aspects of the brittle-ductile transition and creep behavior in this rock have been studied [Robertson, 1955;Heard, 1960 …”

Laboratory hydraulic fracturing stress measurements in salt

“…However, the tangential stress will be reduced from the elastic value if the deformation is non-linearly viscoelastic (Goodall and Chubb, 1970 ;Rata, 1975) or plastic (Robertson, 1955). If the deformation of salt is non-linearly viscoelastic, the tangential stresses in the borehole wall decrease with time, and the breakdown pressure should also decrease.…”

The Quantitative Effect of Hydrostatic Confining Pressure on the Compressive Strength of Crystalline Rocks

“…It is well known that the compressive failure strength of rocks increases greatly as transverse or confining pressure is increased (VON KARMAN, 1911;BOKER, 1915;GRIGGS, 1936;GRIGGS et al, 1951 and1954;ROBERTSON, 1955;HANDIN and HAGER, 1957;HEARD, 1960;MOGI, 1971a and b;others). Various failure criteria have been proposed to explain the effect of pressure or combined stress on the compressive strength of rocks (cf., GRIFFITH, 1924;NADAI, 1950;BRACE, 1960;MCCLINTOCK and WALSH, 1962;MOGI, 1966aMOGI, , 1967MOGI, and 1972.…”