MODELING OF DEFORMATION-CRACKING PROCESSES OF GEOMATERIALS BASED ON A CONTINUUM-DISCONTINUUM METHOD: A CASE STUDY OF COMPACT TENSION TEST

Geomaterials are easily subject to tensile cracking. To model effectively deformation-cracking processes of geomaterials, a continuum-discontinuum method is developed, which is a combination of the Lagrangian element method and the fictitious crack method. This method can be used to more accurately model the stress and strain fields and the complex transition process from the continuum medium to the discontinuum medium. To demonstrate the ability of this method, deformation-cracking processes of rock specimens under compact tension are modeled. The following results are found. Deformation-cracking processes of rock specimens under compact tension are as follows:firstly, the concentrated maximum principal stress is observed at the tip of the Ⅴ-shaped notch; secondly, nodes get separated, fictitious or real cracks extend, and the concentrated maximum principal stress is at the tip of the Ⅴ-shaped notch all the time; finally, the rock specimen is split to two parts. A rapid increase in the maximum unbalanced force corresponds to a nodal separation. Load-displacement curves exhibit strain-hardening phenomena at pre-peak. The peak of stress-strain curve decreases with an increase of the size of the rock specimen, which is consistent with the scaling law of Bazǎnt. Moreover, the post-peak stress-strain curve becomes steep with an increase of the size of the rock specimen. The present numerical results of rock specimens under compact tension are reasonable, indicating the apparent ability of the present continuum-discontinuum method to model the transition process from the continuum medium to the discontinuum medium.