Peak shear strength of natural joints based on morphological characteristics

The surface morphology of a rock joint has a great impact on its shear behavior. The prime objective of this study is to improve our understanding of the shear behavior of natural joints. To study the relationship between the ۳D morphological characteristics and the peak shear strength, ۳۷ direct sheartests on natural joints were carried out under different constant normal loads (CNL). The normal load ranges from ۱ to ۷ MPa. The morphological characteristics of all samples were captured by photogrammetry. With analysis of the shear measured results based on the morphological parametersand using the least square fitting method, a new peak shear strength criterion was presented to predict the shear resistance of natural joints. Finally, the estimation accuracy of the available classic models was compared with the new model and it was observed that the new criterion could predict moreaccurate results. The proposed criterion has the capability of estimating the peak shear strength at the laboratory scale and the required roughness parameters can be easily measured.

Keywords:

Peak shear strength , Natural joints , Morphology , Photogrammetry.