Contact Algorithm for Determining Aperture Evolution of Rock Fracture during Shearing

A contact algorithm to determine the aperture evolution of a rock fracture during shearing is reported. The algorithm was based on a theoretical normal closure model and semianalytical dilation model and required only the three-dimensional topography data of the two fracture surfaces at the initial stage before shearing. It allowed the prediction of the aperture distribution of a fracture under normal stress and various shear displacements, which is difficult to observe in coupled shear-flow tests. To ensure the precision of the surface topography data, a laser-scanning profilometer system was used for surface topography measurement. The contact algorithm was then used to predict the aperture evolution of a marble fracture during shearing. The results of aperture variation under normal stress and shear displacement were analyzed and compared with an equivalent aperture derived from back-calculation of flow test results. The results indicated that the contact algorithm is efficient in predicting aperture evolution. (C) 2015 American Society of Civil Engineers.