Laboratory Investigation and Analysis of the Strength and Deformation of Joints and Fluid Flow in Salem Limestone

Abstract : As part of the underground Technology Program, fundamental mechanisms that influence the mechanical response of jointed, saturated rock masses were investigated with laboratory tests performed on Salem (Indiana) limestone. Mating joint surfaces were created by (1) tensile splitting, (2) sawing and grinding, and (3) cutting to a specified fractal dimension using numerically controlled machine tools. Triaxial tests on specimens with inclined joints were performed to measure joint strength and deformation, and a constitutive model for joints was developed, including the observed strain softening. Permeability of the intact limestone was measured at various stress states including deviator stresses, and joint flow was measured under a range of normal stress conditions. Other aspects of the project included an investigation of strain rate effects, and measurement of the saturated undrained compressibility and specific storage of the limestone. This contract also sponsored ARA's participation in an interlaboratory test program sponsored by the Institute for Standards Research of the American Society for Testing and Materials to develop statements of precision and bias for four standard rock test methods. Rock mechanics, Fractals, Limestone, Rock joints, Constitutive modeling, Permeability.