Influence of Sample Size on the Shear Strength of Structural Plane

The indoor experimental research of structural planes is often limited, whereas that of rock mass is practically extensive. Therefore, using a small structure to simulate the mechanical properties of reactions in a large structural plane is worthy of further study. Then studies for the effects of size on the shear strength of structural planes have important significance. This paper uses samples with a variety of sizes in the direct shear test of structure planes under varying values of normal stress. The results show that, the corresponding shear deformation is small and the shear capacity of the structural plane generally declines after reaching the peak shear stress. Cohesion c was small when the height of the specimen was not over half of its length. If the height is below half of the specimen length, then the internal friction angle increases. When the specimen size is small, the effect of cohesion was limited. The internal friction angle decreases with an increase in size.