Test study of strength and failure mode of pre-existing jointed rock mass

Strength and failure modes of pre-existing jointed rock mass with different joint dip angles, joint discontinuity degrees, joint sets, load strain ratios, slenderness ratios, joint filling's depths and its sort under uniaxial compression are studied by means of similar material model tests. The results show that failure modes and peak strength of jointed rock mass are much related to joint configuration. Shear failure along or tensile failure across the joint face will occur in the continuous jointed rock mass, in which the peak strength is less corresponding to the first failure mode. To discontinuous jointed rock mass, its peak strength lies between that of intact rock and continuous jointed rock mass. With increase of parallel joint sets' number, strength of rock mass gradually decreases. With increase of loading strain ratio, peak strength of rock mass gradually increases; and its failure mode becomes complicated. The slenderness ratio does not change the failure mode of the rock mass; and the intact specimens mainly show tensile failure; while the jointed ones mainly show shear failure. With increase of the slenderness ratio, the peak strength gradually increases; while to joint filling's depth, it is reverse. The effect of different joint's fillings on the specimen's strength exists.