ABSTRACT
An anisotropic and elastic–plastic rock deformation model was developed from the Normalised Strain Rotational Multiple Yield Surface Framework (NSRMYSF) with a slight modification from its application to characterise soil volume change behaviour. It accounted for the presence of cementation. Essentially, the study proved that rock deformed in an anisotropic manner. The NSRMYSF applies the non-linear failure and mobilised shear strength envelopes of Md Noor and Anderson with the application of cementation c′ and the mobilised c′ to account for the cementation. Mobilised cementation increases with the anisotropic compression and reaches the maximum value at failure condition. Various earlier rock deformation models are also presented. The model of Hoek can predict the rock peak strength only but not the complete stress–strain behaviour. The main advantage of this rock deformation model, NSRMYSF is that it incorporates the rock intrinsic mobilised shear strength, which is developed in the rock mass when the rock is uniaxially compressed. The NSRMYSF utilises the fan web structure of the true non-linear mobilised shear strength envelopes and can make a close prediction of the rock stress–strain behaviour together with the peak strength when superimposed with the laboratory stress–strain curves. The applicability of the NSRMYSF is validated against three rock types.
