Geological materials are inhomogeneous natural materials having micro cracks and micro voids. Under the theoretical framework of breakage mechanics for geological material

the geomaterials are conceptualized as binary medium consisting of bonded blocks and bonded bands

evolvement equation of breakage ratio are reflectrd the fracture process degree of the transformation of fracturing or breaking of bonded blocks into bonded bands in the process of loading，which are analysed deformation and breakage development speciality

showed the change course of bonded blocks into bonded bands under loading. Finally

aimed at the loess in Yanglin region

through triaxial shear test

the influences of confining pressure and water content on the breakage rate evolution are studied. The results show that the breakage ratio of simple parameter binary-medium mode has no relation of the confining pressure and water content

it is the function of maximum principal strain from the test.