Slip behavior of rough rock discontinuity under high velocity impact: Experiments and models

The slip shear failure along rock discontinuities is one of the predominant failure modes of landslides. To simulate impact shear loads during landslide and rockburst, an experimental method is presented to achieve the dynamic shear load in a direct shear testing configuration. The dynamic loading system is derived from the SHPB methodology and can provide high shear velocities around 1-10 m/s. Dynamic direct shear experiments on rough rock discontinuities are conducted by using a dynamic shear apparatus combined with a high-speed digital camera. The effects of shear velocity and normal stress on the slip displacement, slip velocity and slip acceleration of rough rock discontinuities are analyzed using a two-dimensional digital image correlation (DIC) technique. It is observed that the rate of the slip is linearly proportional to the shear velocity and decreases with the increasing normal stress. Using the DIC method, the strain at failing asperities is calculated as a function of the shear velocity and the normal stress. The micro-structural characteristics of the shear zone formed in the slip failure is examined to understand the slip failure mode. Moreover, the dynamic viscous is added to the static Barton's shear strength criterion and the damage evolution occurred at the asperities due to the dynamic loading is introduced by means of a damage control parameter D. Thereafter, a dynamic failure criterion is developed by considering both surface roughness and dynamic loading. The failure model can provide a good prediction of the experimental data, indicating that the proposed models can describe well the dynamic shear process of rock discontinuities under high velocity impact.

Automated summary

This study presents an experimental method to simulate slip shear failure along rock discontinuities, conducted by dynamic direct shear experiments using a dynamic shear apparatus combined with a high-speed digital camera. The effects of shear velocity and normal stress on rough rock discontinuities are analyzed, revealing that slip rate is linearly proportional to shear velocity and decreases with increasing normal stress. A dynamic failure criterion is developed considering both surface roughness and dynamic loading, providing a good prediction of the experimental data on the dynamic shear process of rock discontinuities.