Abstract: Subject to geological processes, natural rock fractures can be dislocated to some extent, and the normal deformation behavior of such dislocated fractures has not been quantitatively estimated, and the applicability of classic deformation models has not been verified against experiments and numerical simulations. The deformation and failure behavior of dislocated sandstone fractures were studied via compression tests and elastic-plastic contact simulations. The obtained stress-displacement curves were fitted by a hyperbolic model, an exponential model and a logarithmic model, respectively and the coefficients involved in these models were estimated. The results show that the experimentally and numerically obtained stress-displacement curves agree well with each other, and the surface damage areas are also consistent, which verified the reliability of the elastic-plastic contact model. The hyperbolic and logarithmic models do not fit the curves well under relatively low stress levels, while the exponential model well accommodates the simulation results in the whole loading process by introducing a coefficient n. The maximum closure Vmax is positively correlated with the maximum local aperture, the initial normal stiffness Kni is positively correlated with the elastic modulus and negatively correlated with the fracture roughness and dislocating ratio, and n is positively correlated with the fracture roughness and dislocating ratio. A model was established to predict the three coefficients, and the prediction values agree well with the experimental results.

Key words: rock fracture, normal stress, normal displacement, dislocation, elastic-plastic contact