EXPERIMENTAL STUDY ON INFLUENCE OF LOESS JOINTS ANGLE ON MECHANICAL PROPERTIES OF LOESS

The loess joints with various variety and angles are important factors affecting the mechanical properties of loess. To investigate the influences of loess joints on mechanical properties of loess,uniaxial and triaxial compressive strength tests of loess samples with joints were carried out. The influence of joints angle on shear failure modes,strength and deformation characteristics of loess were analyzed. The result shows that the shear failure modes of the joint specimens can be divided into two types: intersecting of shear failure plane and joint,and paralleling of shear failure plane to joint. Under pressure,wing cracks and secondary cracks initiate continuously at joints tip,which are easy to expand into shear fracture planes. The anti-deformation of the specimen is weaken by joints. The stress-strain curves of the specimen under uniaxial compression present strain softening phenomenon. The deformation modulus at the yield stage and the shear failure displacement of specimens are reduced by joints,which accelerates the shear failure process of the specimen. The shear strength of loess is reduced significantly by joints. The peak strength and residual strength first decrease and then increase with the joints angle,but the variation range decreases with the increasing confining pressure. The cohesion of specimen changes with joints angle more sensitively. The shear strength of specimen is the lowest when the joint angle is 60°. When the joints angle is closer to the shear failure angle of the loess specimen,the joints are easier to expand into the shear failure planes,the anti-deformation of the specimen becomes worsen,the deterioration of the strength becomes more obvious,and the shear failure of the specimen occurs easier. The research results provide a reference for revealing the mechanism of deterioration of loess joints on promoting loess slope sliding.