Experimental Research on Mechanical Properties of Jointed Rock Mass with Different Angles of Inclination

In order to master the deformation and failure mechanisms ofpersistently jointed rock mass, static triaxial tests were carried out on simulated jointed rock mass cylinder specimens, which contained structural planes with different dip angles. The related stress-strain curves and failure results were obtained. Then the influences of dip angles on the mechanical properties of jointed rock mass were studied. The results show that:1) With the change of angles of inclination, the complete stress-strain curves are not all the typical curves including four stages, and the deformation of structural planes are significant when the angles of inclination are large, the curves have evident transitions and the deformation of the structural planes becomes dominant. 2) With the increasing of the angles of inclination, the peak strength, residual strength and the deformation modulus in the linear stage prior to the peak value all reduce monotonously. While for the brittleness, the dilatancy, the deformation modulus in the initial compression phase, and the maximum of volume contraction and expansion, their variation is not monotonous. 3) The dip angle of the structural plane affects the laws of interactions between the structural plane and the rock matrix, which causes that the structural plane or the rock matrix or the two together control the deformation, strength and failure of jointed rock mass. The jointed rock samples exhibit significantly different characters for the deformation, strength and failure. The deformation and strength anisotropy and failure modes vary closely with the joint dip angles.