Study On Mechanical Parameters Of Two Anisotropy Rocks

Rock is made of mineral grains with fissures, beddings and cracks, heterogeneityand anisotropy of rock can occur at micro and macro scales，and it is not nonlinearelastic at a11. On basis of granite and limestone with natural single continuous weakplane, heterogeneity, anisotropy and mechanical parameters of rock were studied.40limestone intact specimens and specimens with the angle of natural continuousweak plane ranged from53°to90°were carried out longitudinal wave velocities,uniaxial and pseudo-triaxial compression. The tests indicate that: longitudinal wavevelocities, dip of specimens with weak plane, and uniaxial compressive strength haveno certain relationship. Failure modes of specimens have three types, sliding-failurealong the weak plane, shearing-failure across the weak plane and comprehensive failure,The filling material of weak plane of limestone is approximately to main body, whichhas same internal friction coefficient0.944with intact specimens. The material strengthof40specimens that the strength of triaxial compression deducts confining pressure isbetween30.3and177.1MPa, the average is121.3MPa，the standard deviation is32.6MPa，which roughly conform to normal distribution; The orientation of the weakestplane of rock varies with specimen whose cohesion is significant difference, whichmakes significant different the strength and failure modes of triaxial compression.Longitudial wave measure, uniaxial compression and Brazilian split test werecarried for a granite to study the relationship among rock mechanical parameters. Thegranite is homogenous but anisotropy significantly. The fissure planes in the granitehave a predominance normal direction, along which the Longitudial wave velocity,tensile strength and Young’s modulus are lower, but the uniaxial compression strengthmay have a high magnitude. The fissures induce axial split and result in the uniaxialcompression strength deceasing along the direction within the fissure plane, but do notinfluence the other parameters observably. Therefore, uniaxial compression strength ofthe granite has a negative correlation with Young’s modulus and Longitudial wavevelocity. In conclusion, the relationship among mechanical parameters of rock need tobe understood after practical analysising the rock structure.