Numerical simulations of scale effects under varying loading conditions for naturally fractured rock masses and implications for rock for rock mass strength characterization and the design of overhanging rock slopes

摘要

It is largely recognized that the uncertainty in predicting the mechanical behavior of a naturally fractured mass is associated with scale effects. In this paper, a coupled Discrete Fracture Network (DFN) - Fracture Mechanics approach is applied to the characterization of rock mass strength at different scale under different loading conditions, including compression, shear and tensile loading. The strength of the approach is that the anisotropic, inhomogeneous spatial distribution and influence of the jointing can be fully considered and the resulting deformation and failure mechanisms simulated in a more realistic way. The analysis provides an example of the definition of both a representative elementary volume (REV) for a naturally fractured rock mass and reduction of its unit mass strength with increasing volume up to the REV. This paper demonstrates that he numerical simulations of rock mass behavior strongly depend on the geological assumptions used to build the DFN models and the mechanical properties of the natural discontinuities. Ultimately, it is believed that to be effective, the use of synthetic rock mass properties requires a correct balance of engineering judgment, the integration of characterized field data, and numerical modeling.