An experimental study on mechanical behavior of joint specimens

In order to investigate the influence of joint on the mechanical behavior of rock mass, the compression shear test was carried out. The joint dip angle and joint overlap were varied to alter the relative positions of parallel joints in geometry. Under compression-shear loading, the failure mode of the joint specimen can be classified into four types: coplanar shear failure, shear failure along the joint plane, shear failure along the shear stress plane, similar integrity shear failure. The joint dip angle has a decisive effect on the failure mode of the specimen. The shear strength of specimen firstly increases and then decreases with the increase of the dip angle, and reaches the maximum at 45 degrees.The shear strength decreases with the increase of the joint overlap. The shear stress-displacement curves of different joint inclination samples have differences which mainly reflect in the post-rupture stage.