In spite of the significant developments seen in recent years,numerical modelin of Hydraulic Fracturing still poses major challenges due to the strong coupling between fluid flow and crack development,which is itself a strongly non-linear problem.The objective of this paper is to show advances in a line of work started by Segura and Carol,on the modelin of coupled H-M discontinuities via zero-thickness interface elements.In particular,this paper is focused on the 3D Applications of the approach,and the results obtained are compared to the existint GDK and PKN analytical solutions.For the comparison, two 3D models are described: a plate model for the GDK, and a block model for the PKN.In order to improve de modelling,both models are run withi nterfaces equipped with realistic non-linear materia llaws based on fracture energy. Results obtained show a good agreement with both analytical and numerical results.