Three-dimensional damage soften model for failure process of heterogeneous rocks and associated numerical simulation

A three-dimensional soften model was established combined with statistical mechanics by taking the heterogeneities on mesoscopic scale into consideration.Two sets of numerical tests were undertaken by using a numerical code RFPA3D to analyze the failure process of rocks subjected to uniaxial compression.One set of numerical specimens was prepared to investigate the influence of the heterogeneities on the macro response of the rocks,and another set was applied to study the influence of residual strength of the mesoscopic scale in the model on soften process.Different from other numerical modeling,RFPA3D could obtain three-dimensional stress and strain fields during the whole fracturing process.Complete stress-strain curves were discussed as well as the number of the failure elements.The numerical results showed that the soften model,heterogeneities in mesoscopic scale and residual strength affected the shape of the stress-strain curve and the soften failure process of the rock.With the increasing of heterogeneities,the soften rate of the rock specimens decreased as well as peak strength,while with the increasing of the residual strength elements,the macro peak strength increased and the soften rate decreased.The results agreed well with observed experimental results and other numerical models.