Effects of void morphology on fracturing characteristics of porous rock through a finite-discrete element method

Abstract

A systematic approach for generating a stochastic void geometry with controllable shape features is proposed for more realistic numerical modelling of porous rock materials. The numerical model (a finite-discrete model) is established by integrating zero-thickness cohesive elements with finite solid elements, to trace the progressive fracturing and failure behaviours of porous rocks. A series of Brazil split tests are conducted on the synthetic specimens that are generated using 3D printing technique, to validate the proposed numerical model. By comparing fracturing patterns and load-displacement curves, it is demonstrated that the proposed hybrid numerical method has promising performances to capture the mechanical responses of porous rocks. In addition, the influences of void aspect ratio and orientation on the mechanical and fracturing responses of porous rocks are discussed. By counting the total damage proportion (Pt) and shearing damage ratio (Ps) of cohesive elements, the hybrid method offered a micro insight to reveal the mechanism of strength variation induced by different characteristics of void morphology. Modelling results demonstrate that better mechanical properties of porous rocks correspond to higher values of both Pt and Ps. Comparison between modelling results and data from literature also validates the efficiency and accuracy of the proposed hybrid approach.