Control factors on shear strength of completely decomposed granite

The relations among the shear strength, microstructure and composition of completely decomposed granite are discussed. The friction angle is mainly controlled by the content of particles greater than 0.5 mm and total content of quartz and feldspar. The discreteness of cohesion is attributed to the complexity of control factors. The relationship between the shear strength and the strain shows that friction has a predominant proportion in the shear strength. And furthermore, it can explain the discreteness of cohesion as well.